Douglasmotorcycles.net
General => General Douglas Discussion => Topic started by: Eric S on 21 Dec 2016 at 21:14
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Hello
I just received my Douglas Aero 1937 and I have some questions.
Replies may be on the Forum but it is so rich, I didn't managed to find them yet.
1st about Clutch.
I ususally start on the Neutral between 2 and 3. However when I need to enter the 2 to reach the 1, I have to enter firmly as the gears "crack" and do not enter if going slow.
Clutch cable is adjusted at its maximum with very little free play left on the handle.
Is that normal? Is there anyother adjustment?
2nd about oil
I received the bike with adjustment opened 1/2 turn.
Douglas manual says that 1 1/2 turn is a normal set up.
However at 1/2 turn, oil drips almost continually, I came to 1/4 turn and I have 1 drop / second or more.
I have a lot of oil (I would say too much) making its way to the chain, rear wheel is greasy and when parked, oil drips from the bike's stand.
Bike do not smoke although previous owners says it should smoke when going up hill.
Any help is welcome here.
Thank you for your help or links to post on the Forum.
Eric
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Eric,
I have a 1936 600 Aero; not on the road but I have ridden one before. A very nice and tractable machine, though not very fast.
Clutch. Like the Velocette clutch, the Douglas flywheel clutch does seem to have a higher chance of being temperamental. For much the same reason, there is little room to spare inside so things need to be in optimal condition.
The best way to check the clutch setting is not at the handlebar, but at the clutch release lever behind the flywheel. With the clutch engaged, this should have the minimal amount of perceptible shake. That will ensure the maximum amount of lift when you pull the clutch lever. As the clutch wears, this gap will decrease, so you need to check the adjustment occasionally. You do not want the clearance to entirely disappear as the thrust bearing will be loaded all of the time and prematurely wear out. The bearing is only used when you lift (disengage) the clutch. Fortunately, the clutch friction material wears very slowly in the Douglas flywheel clutch.
The other issue with the clutch is excessive slop in the components. It is not always wear, as some of it is loose fitting from the factory. The bearings are arranged so they are under the sprocket; more or less. Even so, the chain load tends to tip the clutch plate. A combination of loose fitting parts and minimal lift can allow the periphery of the disk to drag and the clutch does not completely release. Most of this loose fit comes from two locations. The loose roller bearings between the sprocket and the carrier sleeve, and the fit of the carrier sleeve on the hub of the flywheel.
It is difficult to do much with the bearing. The sleeve and sprocket are case hard material. Generally, it is the sprocket bore that is warped slightly out of round. Short of honing and fitting oversized rollers, there is not much that can be done short of a full, engineered replacement of the components. Corrosion and spalling can also take their toll.
A greater source of excess clearance is usually found between the carrier sleeve and the flywheel hub. I have found some of these to be quite loose. As the hub is plated with the rest of the flywheel, I think Douglas left the diameter well undersized so that the sleeve would always fit after plating! This can be a source of problem after re-plating too, as the plating tends to build up a ridge at the end of the hub. I have sorted out this problem by turning the flywheel hub and pressing over it a thin wall bronze sleeve. this also allows the opportunity to lightly hone the inner diameter of the sleeve if it is worn or distorted, and turn the bronze oversized to suit.
Oiling. One drop per second sounds about right; you may find you can cut that back to every few seconds after you get use to it. Do not go by number of turns. Oil viscosity and ambient temperature will many the number of turns mostly meaningless.
Too much oil on the chain sounds like too much crankcase pressure. The oil probably gets dirty very quickly because there is too much combustion gas blowing past the pistons. Could be partial stuck piston rings, or worn rings and cylinder bore.
-Doug
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Thank you Doug for those informations.
I will have to check all this to make sure. However the bike has been supposed to be kind of restoration, flywheel has been re-built...
I am not sure about pistons cylinder and rings but they are also "supposed" to be in good conditions.
As for the oil, is it possible that too much oil from the tap makes this problem without a pressure problem?
Will check that after Christmas,
Thank you for this much usefull help
Merry Christmas
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Eric,
A flywheel rebuild could be as little as a re-plate and assembly! New linings that are too thick can acerbate the lack of clearances inside the clutch.
The oiling system is a three chamber oscillating/reciprocating pump. Very similar if not identical to the A31/A32 model, so you might want to review this post: https://www.douglasmotorcycles.net/index.php?topic=4288.msg15399#msg15399 (https://www.douglasmotorcycles.net/index.php?topic=4288.msg15399#msg15399)
The full supply of the tap goes to the first stage of the oil pump, that pumps to the sight glass. Any oil that the sight glass does not pass (via the needle valve) just returns to the inlet side of the pump via a bypass.
The second stage of the pump evacuates the sight glass bowl and delivers the oil to the spray bar (over the crankshaft). It you have a leaky tap on the oil tank, you might see the sight glass fill up over time if the pump body is very worn. Granted, this would probably in turn leak into the engine past the second stage eventually if the bike stood at rest for a long period of time. I would think if that were the case you would notice a very smokey engine on startup that eventually would clear as the engine burned off the oil and the pump scavenged the excess back to the oil tank.
Scavenge is the third stage of the pump. There is a weir in the timing chest that sets the correct oil level for the timing gears. Any excess goes over the weir and enters the scavenge inlet of the pump.
Oil to the primary chain on the Aero is vented via a pipe from the top of the front tappet chest. Oil mist in the crankcase migrates to the timing chest on the way to the vent. After establishing the oil level as mentioned and excess being scavenged, any residual mist exits via drillings to the tappet chests to oil the valve stems. There are additional drilling lower down to drain coalesced oil back to the timing chest. There is a natural draught to the front chest, as that has the vent to the primary chain.
-Doug
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Doug
I am trying to understand the clutch system and having no access to local knowledge, I have to figure out by myself.
The question I have is about adjustment, or how can I check if the clutch is properly adjusted.
When bike is on its stand, idling, on neutral, the rear wheel turns slowly. Seems normal.
When gear engaged and clutch disengaged, the wheel turns harder and can not be stopped easily. If resting on its wheels the bike very slowly (and on flat concrete) moves forward.
If rider on the seat and feet on ground, bike do not moves.
Now the gear lever cracks when engaging slowly the 1 and 2 gears at stop and needs to be engaged briskly.
When rolling, from 1st, the 2 engages well.
So my question is to know if I can ride this bike, entering the 1st gear like a man, or the clutch actually needs to be looked after.
Thanks again for your help.
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Looks like classic clutch drag symptoms where the clutch is not fully disengaging. As described above, the problem can be caused by many things. My EW has had similar problems and as the clutch gets hot when in traffic a previously free clutch can expand to cause drag too. I have found that adjusting the cable so the minimum perceptible play is felt on the lift arm behind the clutch should give a free clutch from cold. If not you may have an oval/worn bearing track causing the clutch plate inside the flywheel to tilt. Having the primary chain too tight will make it even worse. Try running the primary chain much looser than you think is appropriate. I also found that the lift arm tracks where they contact the pins on the crankcase were worn so I machined them back slightly to give a smooth even lift. I replaced the pins too as they were worn as well. Some re-lined friction plates have been made too thick and as there is limited space can cause the plate to not disengage as will excess friction/rust dust. I experimented with spring length and strength to make the clutch light but effective. If all of this fails it is likely the bearing track will need some help! Its a case of fiddle or dismantle and measure. Once it is apart it is self explanatory as to how it all works. The drawings can be a bit confusing.
Hope that helps
Andy
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Thank you Andy
However, do you think the clutch on my bike, based on what I tried to describe, needs to be adressed?
Is it normal or not that the gears "crack" when engaged on 30s bikes?
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From what you describe I think you need to address the clutch problems.
The bike should not be trying to move whilst stationary and in gear with the clutch disengaged.
It takes a bit of experience getting the revs and timing right when changing gear on hand change bikes and they can grind a bit if you don't get it right.
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Hello
Anyone can let me know what this adjustment screw is supposed to adjust and is it normal it do not sits well in place?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/IMG_2568.JPG)
[Attachments converted to linked images. 27Nov21 -Doug, Admin]
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It is not an adjustment. The chain case bolts up hard against the frame lug. Looks like a little bit of the chain case ear is broken away; it should encompass the bolt hole. Mine just had a plain hex head bolt, not a shoulder bolt.
-Doug
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Can you send a pictures of yours?
Mine is also a plain hex head bolt.
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Mine is apart, but I know I took a photo of this very detail at the Douglas Cavalcade a few years ago. I finally found it squirreled away on the computer hard drive. It is nothing fancy at all. Perhaps the original nut was curved to match the i.d. of the tube, but I do not recall seeing such in the bits and pieces of the two Aeros that I have.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-primary/Aero-primary-frame-attachment.JPG)
-Doug
[Update image path. 22Sep17 -Doug]
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Thank you for the effort. It is well what I understood from your previous description, I was not sure. I will have a closer look tomorrow and see how/of I can make the 2 parts in close contact.
And how I can have it "repaired".
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Well I had a closer look this morning.
The part is a bit greasy but from a quick look, I am not sure that the part is actually broken and looks like it is suposed to be open with bo "ear" and the finish is smooth and do not appear to be broken.
To bring him closer to the frame, it looks like I have to take the engine back, then the gear box to maintain the primary chain tension (which is quite loose to this day, concern expressed by Andy).
Now is the question as why it is mounted this way by previous owners. They may have their reason. So is it better to leave it this way???
Can this set up has any effect on the clutch? I don't think so??
As usual, any input more than welcome.
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The four examples that I have seen just have a hole.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-primary/aero-primary-rear-attachment.JPG)
At the front, as you probably have seen, there is a little amount of adjustment possible for the engine.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-primary/aero-primary-front-lower-attachment.JPG)
-Doug
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Hello
I tried to make the chain cover closer to the frame and although I still have adjustment left on the mounts, the part is touching somewhere inside. With the flywheel in place, I can not see what is going on there. So I fear I have to let it where it is for now.
I came across this rod that goes between rear of engine and frame. What is is supposed to do?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/20170128_112335.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
That is the "engine adjusting rod". It pushed the engine forward to adjust the primary chain, and stops the engine from creeping backwards over time.
-Doug
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Thank you Doug
I managed to figure out what the purpose of this rod was in the meantime.
I actually used it to move the engine forward a bit as the primary chain was quite loose.
I also opened the clutch and cleaned the disc. It was covered with a kind of greasy residue that was sticking.
I will have to test the bike but the feel is better.
Also the stand stop is partially "unwelded" and I have to reweld it over the week end. The stand moves too much forward and both wheels remains on the ground when on the stand?
I hope I can repaint the frame to a good standard after this is done.
Besides this, an electrical problem arose and one of the 2 screws that hold in place the chain cover onto the engine has failed. I will try to find a longer screw and see if I can get to fresh threads...
This bike keeps me busy.
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Hello one more time
Several bolts and nuts went off and it appear they were not of the correct thread.
What is the thread standard used on those bikes. Is it metric, US or anything else?
Where can we get replacements and how to repair a thread on the engine block? (Primary Chain cover)
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Eric,
Most of the threads tapped into alloy are BSW. A lot of the other threads are proprietary Douglas, though by the mid-thirties many of these finer threads had been replaced by BSC. I do not think there will be much BSF found on the Douglases until postwar.
Here is a post covering some of the threads in use by Douglas, though nominally up to 1926.
https://www.douglasmotorcycles.net/index.php?topic=1102.msg3721#msg3721 (https://www.douglasmotorcycles.net/index.php?topic=1102.msg3721#msg3721)
-Doug
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The 4 bolts clamping the engine on the frame seems to be 3/8” x 20 tpi so it would mean they are BSF.
I am not sure of the 20 Tpi though. It seems to be just a little bit more, the thread gage do not sit well on it.
We have BSW clamping the gearboxx on the frame and the primary chain cover on the engine block.
Most others I checked are BSC.
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Eric,
Could be BSF or BSC. BSC had a 26 and a 20tpi series. Probably the bolts have stretched a little. I think it was a chronic problem keeping them tight enough. Between the frame tube collapsing, the clamp stretching, and so on, the owner was left with winding down on the bolt more and more in a fruitless attempt to keep the engine from slipping back.
-Doug
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Doug
do you mean the engine was slipping back anyway?
Beside this, I am still trying to fix my clutch problem. The clutch do not open enough and the gear cracks and the bike want to roll when clutch lever pressed and gear engaged.
The clutch/flywheel assy has been inspected and nothing seems wrong in the clutch.
The period litterature I got with the bike says that the operating cam should open the discs for about 4mm/3/16". (Although I can not find it now and I can find only that the operating cam should lift to a distance of 3/16" so I might be wrong here)
I am far from that with a mere 1-2mm.
I really think the cable travel not enough or at least the operating cam do not rotate enough. Only 1/3-1/2 of the cams are used.
As there is no way to change the cable travel, I come to think that I may have the wrong op. cam and/or the wrong primary chain cover???
I noticed that there is a potential second position for the cable on the op. Cam's lever and a matching hole in the cover where I slide a screwdriver in the picture below.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/douglas-aero-clutch-adjustment.jpg)
Image aspect ratio corrected - Dave, 25May2021
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Eric,
If the engine adjuster rod was left with a gap, it slacked off, or the rod bent upward and allowed a gap; sure the engine would probably work its way backward.
You want to maximize the throw of the clutch cam, so that means maintaining the minimal amount of slack in the cable adjustment. Best means is to allow only a little shake of the clutch cam. This will take the pressure off the clutch throw-out bearing. Don't try to set it at the handlebar or by lifting the cable casing at the primary cover adjuster. Those will leave too much slack.
I have seen the second 'boss' on the cam operating arms on the Aero models. Presumably they wanted the same die to be suitable for either style, though I have never seen an application using the shorter arm. Nor does my primary case have the second hole you point out.
-Doug
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Hi to make my clutch operate better I reground the angles on the outer operating plate to a steeper angle .This makes the clutch travel further but slightly heavier to use .Works well now no drag !
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Well I had a closer look this morning.
The part is a bit greasy but from a quick look, I am not sure that the part is actually broken and looks like it is suposed to be open with bo "ear" and the finish is smooth and do not appear to be broken.
To bring him closer to the frame, it looks like I have to take the engine back, then the gear box to maintain the primary chain tension (which is quite loose to this day, concern expressed by Andy).
Now is the question as why it is mounted this way by previous owners. They may have their reason. So is it better to leave it this way???
Can this set up has any effect on the clutch? I don't think so??
the primary chain by virtue of the engine sprocket moving out when the clutch operates, means the chain should have enough slack so it will allow the centre line to change, to tight and clutch will drag
As usual, any input more than welcome.
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Ken Rogers
Why do you had to reground the plate to a steeper angle?
Do you also had cracking gears on yours?
Before the alteration by how much did you moved out the clutch. I only have 1-2mm.
This modification has been sugested by a friend but seems a bit difficult to make well and I don't want to do it if the problem comes from elsewhere...
Polly,
I made sure the primary chain was loose enough.
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Eric,
Check that the friction plate is not dished or distorted, and make sure it runs true to the bore of the hub - otherwise it will always be dragging against either the flywheel or the pressure plate.
Regards,
Eddie.
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Eddie
I will check the discs runs true.
Right now I am trying to remove the rear primary chain wheel and I am not sure if it's ready to go.
There is 2 nuts that are still in place and I don't know if they need to be removed first.
Looks like these nuts needs to he hammered unless a special tool exist.
By now I removed the washer that I left for the picture.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/20170213_195337.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
There is just the central nut (which you have removed), and the entire chain wheel and cush-drive hub assemble should pull off of the input shaft taper. There will be two Woodruff type keys on the taper.
-Doug
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I got it off.
I assume the next wheel on the gear box shaft requires also the same extractor?
What is the most period correct finish on the aluminium parts?
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Yes. Same general design of nut, tab washer, taper, and two Woodruff keys.
-Doug
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Eric,
To remove the final drive sprocket, you will need to have a spacer tube and end plate to go over the inner shaft, so that the pressure is applied to the end of the sleeve gear (not the end of the inner shaft). Pressing direct on the end of the shaft is likely to result in the gearbox case being damaged.
Regards,
Eddie.
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Going deeper and deeper.
I reached the gear box shaft where I have a nice oil leak.
What will I found beneath this, what kind of gasket shall I expect and how is it easy to replace?
Concerning the clutch that do not open enough, I made a picture of the part where the cammed wheel turns. I was wondering if there is any adjustment here where I could move it clockwise to kind of "preload" the system.
I made a set up using a comparator that ran through one of the compression spring hole.
With the clutch/flywheel in place, moving by hand the cammed wheel all the way in and out moved the disc .138"/3,5mm.
Connecting the cable and using the clutch control on the handle bar, the disc moved out 0.065"/1.5mm. That is the maximum traveling available using the control.
Is that enough? How to improve that?
I checked the "flatness" of the disc. It runs at about .010"/0,25mm.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Vilebrequin_Sortie.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Boite_a_Vitesses_Sortie.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Hello there
I am blocked with my gear box that leaks. Please see picture just above.
Anybody may let me know where I can have some information about the gasket used there, where to get it, and how to dismantle the internals as I fear that the only way to reach this gasket.
Any help will be much welcome.
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Eric,
The gland is accessible from the outside of the gearcase.
The outer hardened face washer of the sleeve gear bearing has a conical seat. In this seat recess is a leather (or possibly felt) washer. There is a thin collar of "L' shaped cross section pressing against the face of this, which is in turn pressed upon by a wave or spring washer between the gland and the output sprocket.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-primary/gearbox-sleeve-gland.jpg)
This illustration is for a 3-speed gearbox, but the 4-speed 'box should be the same design.
-Doug
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the gearbox is filled with castrol spehrol, thats why there is a grease nipple on top!
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Thank you Polly
I am still wondering why there is a greaser, and 2 nuts for draining and filling??
However I have a liquid oil running though the shaft as you may see on picture.
Of course if there is supposedly no oil in the box, that would solve my problem.
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Eric,
The type of lubrication for the Douglas gearbox is a re-occurring query here on the Forum. It is a Thixotropic grease, or in other words, self-leveling grease. You can buy it, but most owners make their own by mixing grease and heavy gear oil. The right consistency is you drag your finger through it, it should self-level in a minute at room temperature.
If you use straight gear oil, it does not stay in the gearbox very long. If you use straight grease, the gears cut a path through it, shove it aside, and eventually starve for lubricant. Also it is too thick and viscous to lubricate the sleeve gear bushing.
-Doug
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Doug
sorry I have some trouble finding some information on the forum that is way too large for me and have not been too lucky when launching requests.
I checked the box. I have a filler on top, a drain plug underneath and 2 plugs on the sides.
One is at the same level as the shaft, probably for the level? The other one 45° down. Probably a 2nd draining plug.
Consistency is difficult to appreciate. though. But if leaking, it might be too liquid...
I guess the best would be to drain the existing oil and replace with Castrol Spheerol that Poly recommends. That would eliminate the question.
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Polly
Castrol makes several Spheerol.
It can be LCX-222, SY-HT2, EPL-2 or EPLX 200-2??
Doug, would you have an ersatz recipe?
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Eric,
I thought I had a broad vocabulary, but I had to look up ersatz! :)
No, I do not. I just mix it up ad-hoc when required. Usually in a disposable plastic drink cup, as only a small amount is generally required to fill a Douglas gearbox. For the grease I use general purpose wheel and chassis bearing grease as there is usually a tub on hand in the workshop. You do not need a grease with lithium, though it probably will not affect the outcome. For the oil, generally 90W gear oil or 600W steam oil, depending on what I have laying about. Avoid oils with Extreme Pressure (EP) additives as those can attack certain types of bronze. Mix oil into the grease well until it starts to go fluid. As I mentioned before, my viscosity test is to drag a finger through the surface and see how long it takes to level out. It should be a full minute for the 'groove' to vanish.
-Doug
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After all you learned me, I am glad I improved your vocabulary !
I guess I will try your recipe as I can not find the right grease. So I can rock 'n roll this week-end... maybe.
Any idea of the volume needed to fill the box? I am a bit concerned about the way I will be able to "read" the level with such a compound not setting down rapidly.
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Eric,
You just have to be patient. It is going to be slooooooow to pour in as well!
I have never seen a published capacity for the gearboxes. I guess it is about 1 pint or 0.5L. The lower shaft needs to dip into the lube in order to throw it around inside the gearbox. If you over fill it, the excess will have no trouble finding its way out!
-Doug
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I use a syringe. A big one and inject it through the top.
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Draining the gear box. Grease is way too liquid per Doug's specs. Did not pass the finger test. By Far.
Will add some grease to make it less liquid and put it back, less the volume of grease added and I should not be far from being right.
In the meantime I cleaned the outside. Tried to remove a black paint that appeared to be kind of cement to plug probably a hole in the box or maybe something else removed?
Should I ever have to open the box in the future, I will have repaired with "real" aluminium.
Also I am wondering what might be the function of the plug that has a spring loaded plunger on it??
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Boite_a_Vitesses-2.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Boite_a_Vitesses-1.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Well finally it was less easy than expected to get the right feeling of thickness. Adding grease, then oil then grease and a bit more oil.
I ended up with what I thought might be right and put the whole mess back in the box (making the grease more liquid by heating at Bain Marie, hey french can cook, it's genetic), level plug open, waiting for everything to come doooooown and self leveling through the port.
Nothings showing up after a couple of hours.
Too thick now?
Will check back when back from skiing middle of next week...
Thanks again for all your help.
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Eric,
The plunger is the detent for the shift cam drum.
Unless you are certain you mixed up more grease/oil than came out of the box, you will have lost some while pouring it in as it sticks to the case, gears, and shafts on the way down. Even though it is self-leveling, it still is very viscous and will cling a thick film to surfaces. Stick a bend piece of wire in the level hole to see if the level is sitting just below the port. It will give you an idea how much more needs to go in.
-Doug
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Castrol's Spheerol gear box grease is available from National Motorcycle Museum
http://www.nationalmotorcyclemuseum.co.uk/product/castrol-spheerol-lepo-500gm/
That is yet another Spheerol, not in their regular line, more in their classic line.
Doug,
I added 3 flush Table Spoon of grease, 1 of Oil, lost probably a maximum of 1/2 to 1 TS in the process so I am certain I mixed upmore than came out of the box.
And still nothing shows up at level port or 10mm below as I can see with a bent piece of wire...
Will check again in a few days.
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Well, 2 or 3 days later, grease level remains 10mm below the level plug...
I am wondering if level was too low when I started (and did not checked !) or if it is too viscous and sticks to the upper parts of the box.
And the box is still leaking from the shaft !!
I can see a slight play in the shaft. Don't know if this is normal.
As for the foot rest, is the set up below original, with a long threaded on both sides rod and nuts on each end locking everything in place.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/20170228_144803.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
With the output sprocket off, there will be a small amount of axial (end) play in the output shaft. With the sprocket on, the spring washer against the seal should eliminate any axial play. There should be very little radial play, or wobble. However the roller bearings are not spaced very far apart and much of the alignment is provided by the fit of the input shaft through the sleeve gear busing. If that is worn, the sleeve gear can wobble on the shaft and the roller bearings do not have a wide enough 'stance' to prevent it. The input shaft should have a small amount of axial play at all times and no perceptible radial play. Again, if the sleeve in the output shaft is worn, you will be able to wiggle the shaft up and down. If you can perceive it (0.15mm) it is worn out.
Yes, there is a rod that passes through the footrests with nuts on the outside clamping everything together. It looks like the face of the footrest and the sleeve have been modified. These should have a face serration to allow angular adjustment. Pictures of mine attached. The serrations for the brake pedal side are almost entirely worn down. I made new ones. I re-cut the serrations on the foot peg arms.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/serrated-1.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/serrated-2.JPG)
-Doug
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Actually, you may want to ask around about the footrest serration. Perhaps Douglas changed that for the 1937-38 models, because the serrations getting worn and mashed was a chronic problem. -Doug
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As for the foot rests, I can see remains of serrations but INSIDE of the right only foot rest. Like if the rod should have matching serrations.
Nothing can be seen on the left.
Any way I will mount it back the way it was. I have more than I can handle for now.
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I do have a small amount of axial play on the output shaft. (Providing output shaft is where the Sprocket for Primary Drive mounts or larger shaft)
However I have no "spring washer against the seal". Do you have a picture of that?
Providing input shaft is where the Sprocket for Secondary drive mounts, or small inside shaft, I have no perceptible play between it and the output shaft.
I am not sure to understand what is the "sleeve in the output shaft" though.
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I am not able to identify the thread size of the screws holding the front brake.
I thought it would be 1/4 26 Tpi BSC but is seems to be just a little bit asmaller and 1/4-26 do not screw there.
The original screws on the bike were Allen socket head screws. Anyone has the information as to the correct head shape on those screws?
Also how can we remove this triangular shape plate. Seems to be locked on the square shaft. Do I have to remove the front wheel?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Frein_Avant.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
The original fasteners would be hex head, Whitworth wrench size across the flats. While Allen head socket cap screws were available for the 1920s onward, Douglas did not use them until postwar.
The triangular plate is some sort of modification. So no telling how it was put together. Attached is the very original (and rusty) front end of my 1936 Aero. Also a picture of just the brake backing plate (sorry about the low resolution). The brake arm passes through a bush in the girder fork blade and plugs into a spline inside the brake. A bolt through the center holds the brake arm and shaft from falling out.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-f-brake-1.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-f-brake-2.jpg)
Markup of the sleeve gear, labeling the parts. I do not happen to have a picture of the wave washer, but it is of the same design as waver washers still sold today.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/gearbox-sleeve-gland-edit.jpg)
-Doug
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I just remind that the front brake has been changed by a previous owner. I guess they installed Triumph parts to make it more efficient.
As for the leather gland, is it something hidden inside?
I guess I still miss parts as I can't see how a wave washer stuck between the rotary sprocket and the fixed gear box would handle the friction. Don't I need a ball bearing or the like?
Also I have 3-4mm between the gear box wall and the sprocket. Isn't it too much for a wave washer?
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Hello there
On the front brake, original screws seems to be 26 Tpi and about 1/4 but I can not screw in a 1/4-26 screw. So what it might be?
Doug that is your "bolt through the center holds the brake arm and shaft from falling out".
Doug again, from what I understood on your previous drawing, I should have a leather gland, a backing washer and a spring or wave washer. If those are 3 loose parts that are taken between the gear box and the sprocket, I am lacking them.
Below is a picture of the shafts out of the gear box. I only have the Sprocket to install there.
I found a round gasket, that comes to be slightly compressed between the box and the sprocket. Is that a decent solution unless anyone can tell me where to get the right parts?
Current spark plugs are NGK BP7EVX. Those are completely worn out. Is this model OK? Bike Works well with it...
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Sortie_Boite.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Hi Eric,
It looks like someone has fitted a "modern" lipped seal to replace the original leather seal. Since it has been leaking, I guess you need to replace it. Try to find a replacement before you try to get this one out because the metal casing is often very thin and will probably be ruined if you take it out from the outside.
A gasket of any kind between the case and the sprocket will not work: it won't seal the shaft and it will probably spin with the sprocket and wear the aluminium case away.
Cheers
Leon
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Hello Eric,
Remember when I said "if they used the same design as the 3-speed". Well they did, and they did not. I pulled the sprocket off of my 1936 Aero gearbox and the seal is not the same as the 3-speed. The housing has no external access to the seal, as you can see in this picture. The aluminum comes right down to the journal diameter.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-gearbox/1936-gbox-1.JPG)
Which did not match you photo at all. So I looked at another gearbox, this for a 1932 Greyhound 4-speed. It has a design like the 3-speed and the section illustration that I previously posted.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-gearbox/1932-gbox-1.JPG)
Just to the rear of the keys you can see the spring washer. The spring washer and the backing washer behind it are shown below. The leather gland was missing.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-gearbox/1932-gbox-2.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-gearbox/1932-gbox-3.JPG)
With this style, the back of the sprocket has a more pronounced spigot that projects into the end recess of the gear case and bear against the spring.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero-gearbox/1932-gbox-4.JPG)
The 1936 sprocket only has a slight hub. The 1936 gearbox for the Aero has a P prefix, the 1932 gearbox for the Greyhound has a GB prefix. It looks like you have this earlier style gearbox?
The spring has a cross-section of 0.062 thick by 0.093 radial, 1.531 outer diameter, and a free height of 0.200 (all dimensions in inches). The backing washer is formed by rolling a lip. The material is 0.036 thick with a inner flange rolled up to make a overall width of 0.088; the outer diameter is 1.739 and the inner diameter is 1.293 (inches). The lip faces outward, towards the spring.
-Doug
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Eric,
The bolt that secures the brake lever is 1/4-25, a Douglas proprietary thread. They also used 17/64-25 (like for the petrol tank mounting bolts), so you have to be careful.
Picture of the brake arm and bolt in this post:
https://www.douglasmotorcycles.net/index.php?topic=2440.msg8835#msg8835
-Doug
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Leon
thank you for your expertise.
The round gasket I'm talking about is a round rubber ring. Being compressed it should pressure the shaft out of the box and limit the leak. Being rubber it should be harmless and help for a while.
I'd prefer to have the box opened, the modified gasket inspected and replaced but can not find anybody locally that may do it. Though waiting replies.
Doug thanks one more time. Don't know what to do. Maybe as just said give this rubber ring a try.
As for the bolts, the "bolt through the center holds the brake arm and shaft from falling out" will be re-installed. I wanted to change as it is an Allen head but will leave it as it is a 1/4-25 and can't find a correct hex head bolt in that size.
I will helicoil the 3 screws on the triangular plate and makes them 1/4-26. The original bolts seems to be also 1/4-25.
Anyway since they were Allen and loctited over worn out threads, I had to discard them + I should be able to live with 1/4-26 there.
The drum being a Triumph, is it possible Triumph also used 1/4-25 there?
On the tank I had a missing bolt so got 4 new chromed 1/4-26 bolts and they screw in 4 turns before being hard to turn. Are they bottoming out or are they 17/64-25?
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Eric,
The petrol tank bolts are 17/64-25.
-Doug
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Doug
I measured the 1/4-25 bolts and they are .232"
Seems a bit small for 1/4"?
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Since they're Allen heads, they might be M6 (6mm x 1mm pitch - 0.236 - 25.4 tpi)!
Leon
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Well done Leon, it's well a 6mm bolt.
This bike seems to be a sample of every thread size available in the world.
I re-installed the gear box, clutch flywheel, ...
With the knowledge I acquired through the forum and reading period manuals, I came up to the conclusion that my clutch problems might be linked to an overloaded clutch counter acting on the cam plate/cable action.
So I thought I would adjust the springs to a minimum.
But I think I have too strong springs in there.
Using 2 springs (instead of 6) and screwing in the adjustment nut just 1 turn, I have the plate out of its location but the clutch seems to function and I can turn the primary chain sprocket by hand without turning the engine (so Clutch is well off)
Screwing more prevent that and turning the sprocket turns the engine.
I did not started the engine yet and did not tried "live" but I am really wondering if the sprins are OK.
They are 40mm/1.57" and wire is 0.80"/2mm
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Clutch_Springs.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Looks like the tank bolts has been helicoiled that would explain the 1/4-26 Tpi bolts fits.
I also noticed the engine bolts fits into inserts that I do not have on the gear box where bolt screw into aluminium. But the inserts are the correct thread size.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/Reservoir.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Does anybody have any idea regarding the clutch springs discussed just above?
Are they too strong?
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Eric,
I don't know that anyone bothers to measure them. New ones are available to LDMCC member via the spares department.
As for the engine and gearbox mount. The engine is supposed to have the steel inserts, the gearbox was tapped directly into the aluminum.
-Doug
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Thanks Doug
I will check with the club.
I noticed a play on the rear wheel sprocket. Do I have a torque converter here?
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HI Eric
I have just measured six clutch springs purchased at different times over the years from LDMCC spares. No two are identical. These are a fairly fast moving item and have been purchased from different sources probably on the basis of samples supplied as patterns. The lengths vary between 35.68 and 37.35mm, appreciably shorter than your springs of 40mm. Diameter of coils vary between 12.64 and 13.19mm. The wire diameter also varies between 2.01 and 2.12mm. The subject of clutch springs has been discussed previously on the Forum as other members have experienced difficulty with clutch operation. From my experience with four different models with flywheel clutches none of them needed more than four springs to function well even including a 350cc CW with passenger sidecar.
Chris.
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Eric,
I noticed a play on the rear wheel sprocket. Do I have a torque converter here?
Do you mean a shock absorber or cush-drive? If so, no, the rear sprocket is supposed to be rigidly mounted to the rear brake drum/hub/wheel. Having said that, it is only pressed on to a knurled portion of the brake drum. There are several key/blocks that transmit the torque.
-Doug
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I don't really know what I mean !
But shock absorber or cush-drive seems to be what I had in mind.
A friend told me that if the large toothed wheel (with the chain on) moves on the drum where it is installed, then it might be a torque converter.
If it is supposed to be rigid, looks like a new field to play with...
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I tested the bike with 2 springs (out of 6) on the clutch, tightened just the minimum I could.
Worked fine but gears still cracks and when going up hill on 4th, the clutch slipped so I had to come down to 1st gear. (steep road) and went back home safely. I hadn't a chance to make more tests as I have to another toy to play with for now.
Cracks seems to be manageable though. Will make more tests later.
Now I also have an elecrical problem. The bike's harness is a real mess with blue wires connecting to reds. Ground being any color but never black !
Dess anyone has a wiring harness plan or drawing fopr a 1937 Aero?
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I am sorry that nobody can help with a wiring diagram for my bike.
I can not find a regulator before the dynamo. Are we suppose to get one?
I do a have a diode leaving the amperemeter. Is this replacing the regulator?
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Eric,
I don't have any first hand information regarding the wiring on an Aero, but I would assume that it is much the same as that on a 1930 S6 as both machines are fitted with 'Pancake' generators. The S6 has a single wire from the generator to a cutout that prevents battery voltage draining back through the generator windings at low engine speeds. The other side of the cutout is wired directly to the ammeter, and then linked to the lighting switch input terminal. The other side of the ammeter is wired to the live side of the battery. The only provision for voltage regulation is via a ballast resistance on the lighting switch.
As your bike already has a diode fitted, it would appear that the original cutout has already been superceded. If your bike is fitted with an electric horn, it should be wired directly to the live side of the battery - not through the ammeter!
Hope this is of some help,
Regards,
Eddie.
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Thank you so much Eddie
Yes the bike as an electric horn and is wired directly from the battery.
I am forwarding the rest to my helper as I am not able to grasp all the details here.
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Eric,
I have not yet seen a handbook published for the Aero models, just parts lists. So neither have I seen a wiring diagram. It would have to worked out from contemporary systems.
-Doug
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Thank you Doug.The bike has been well modified so I am even wondering if a wiring diagram would really help.
Eddie, can you explain briefly the reason why the horn must not go through the ammeter for my personal education?
As for the ballast, I have no idea the way it looks. What I am looking for here?
On the ammeter, I have on one side a direct wire from the + on the battery, and the diode going down (to the dynamo but did not checked it). On the other side of the ammeter, a wire goes to the lighting switch input terminal.
You showed it slightly different with dynamo and lighting switch on the same side and + on the other side.
Does it makes any importance there?
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Eric,
It is normal practice to wire the horn direct to the battery as the ammeter is probably only rated at about 4 amps and the horn's start up load could easily exceed that.
The ballast may be a ceramic coated resistor or just a coiled bare wire between 2 terminals on the switch.
The ammeter should have just the battery connected to one side - the generator lead (with the diode) and the connection to the lighting switch go to the other side of the ammeter. Wired this way, the ammeter will read the current either going to the battery (charge), or being drawn from it (discharge) - thus giving a continuous reading of whether you have enough charge going to the battery (very important on the Aero as those pancake dynamos often didn't keep up with the drain of a headlight bulb!). One of our local Club members had a 600 Aero that had a reputation for going well, and would often be seen disappearing into the distance - until nightfall - then his battery would go flat within about 15 miles - at which point, he would have to rely on following someone else's taillight!
Regards,
Eddie.
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This is all that remains of my Aero wiring harness. with the exception of the headlamp dip lead, it had been cut where the main bundle left the headlamp shell.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero/1936-switch-1.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero/1936-switch-2.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/aero/1936-switch-3.JPG)
-Doug
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Is this white curved part with a wire around it a ballast?
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I played a little bit and wrote down the harness as it is with colors for the wires.
Beside the diode to dynamo wire that has to be linked to the other side of the ammeter as Eddie required, did any of you see any big mistake or useless connections?
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Here is the dynamo, can you let me know where I can plug the earth and the "diode" wire (sorry picture is up side down)?
On the lighting switch, do you see a ballast (picture again not straight) ?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/20170414_133504.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2017/20170414_133440.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
As we are looking at the photo of the dynamo (upside down) - the terminal at 4 o'clock is where the diode wire should go. The terminal at 9 o'clock has been added, but is not needed - the dynamo is designed to be earthed via the crankcase and frame.
Looking at the lighting switch, I am assuming that it is a 3 position switch - that is 'Off - Sidelight - Headlight', and that the switch was photographed in the 'Sidelight' position. If that is the case, your wiring diagram looks to be correct, but with that Lucas switch there is no provision for switching in a ballast resistor. If you have a speedo fitted, the speedo light should be wired to the same terminal (7) as the taillight.
Bearing in mind that the output from those 'Pancake' dynamos is pretty dismal, you should get away with leaving it permanently connected - it is very unlikely that it will boil the battery dry.
Regards,
Eddie.
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Yes, the white thing is a half-charge resistor.
A ballast resistor is (I think) a resistor used in the specific application of older coil ignition systems with mechanical points.
Here, it is a half charge resistor to prevent over charging of the battery (or accumulator in English). Which is a bit silly, as Eddie says, the output of the BTH pancake dyno is so feeble that overcharging is farce. I suppose back in the day if you ran all day and every day with little night time running the lack of headlamp load could over charge and boil the battery dry. But these days the systems are under-performing (if even working!), the usage is occasional, and often the headlamp on during the day as a daytime running light.
-Doug
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Eddie
I have an earth wire linked to the 9 o'clock terminal. Should I remove this wire or leave it plugged?
Yes its a 3 positions switch and it's well set on sidelight on the picture. And it has no speedo.
When you said I "should get away with leaving it permanently connected", do you mean that I can leave it permanently connected? Or stay away to leaving it ...?
Do I understand well that the ballast (or half charge resistor) should regulate the voltage so as not to overcharge the battery?
When I bought the bike I've been told that the battery charging by the dynamo was very low so, as Doug pointed, overcharging is not a problem !
I tested the dynamo and I read an 8V output when accelerating the engine a little bit. Sounds to be not too bad but is it relevant or should we check Amps?
How can I check, when everything will be connected and battery installed, that the battery charges beside reading he ammeter. How can I get a value on my meter?
Somebody tested the battery with engine running, connecting on the battery connections and said it was "not charging"?
And is the way the ammeter is wired now, is it possible that the ammeter gives false or no reading?
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Eric,
As I have already said, an earth wire from the generator is not necessary as the unit is earthed through the crankcase to the frame.
Originally, the Aero models were fitted with a Miller lighting switch that was designed to have a ballast resistor (half charge resistor) incorporated in the wiring. Turning the switch to the headlight position would also bypass that resistor so that the full charge rate went to the battery - your Lucas switch does not have that facility, so I would suggest that you should connect the generator via the diode to the ammeter. Connect it to the opposite side of the ammeter to the battery - then any power coming or going from the battery will register on the ammeter. The way it was wired (with the battery and generator on the same side of the ammeter) meant that any charge going to the battery didn't have to go through the ammeter, so the ammeter wasn't reading it.
When you have everything wired up as I suggested, you can run the engine and see on the ammeter how much charge is going to the battery with the lights off. If it is in the region of 2 - 3 amps, the battery should cope with that. If it is more than 3 amps, you may need to insert a ballast resistor in the generator wire - in order to then get the full charge rate with headlight on, you just need a simple on-off switch wired across the resistor so that you can bypass the resistor when you have the headlight on (thus replicating what the Miller switch did).
Regards,
Eddie.
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Eddie
I well understood that this wire was useless but it is here. So I will see if it's easier to leave it or remove it.
As I like to understood what I am doing, I came to the terminal at 9 o'clock and checked it for earth. And it is, as expected. So far so good, it was easy.
I then checked the terminal at 4 o'clock the one that has the "dioded" wire coming down from the ammeter with +. But this terminal is earthed too. Am I missing something here?
Is it normal due to the nature of the dynamo and the way it works (earth until it comes in production)?
The Diode being supposed to "block" the + going down to the dynamo?
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Eric,
The terminal at 9 o'clock is showing a connection to 'earth' because there is a connection through the armature windings. If you were to lift one of the brushes, it would show 'no connection'.
Eddie.
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Eddie
sorry I was talking about the other terminal being on earth. The one at 4 o'clock with + wire with diode.
(Actually both terminals are on earth)
Is that normal?
Eric
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Sorry Eric,
Yes, it's the terminal at 4 o'clock that is connected to the armature windings. With a test meter it will show as being connected to earth due to the low resistance of the windings.
Eddie.
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I road tested the bike and although the dynamo seems to output 8V as I measured it some day ago, the ammeter says "0". When lights are on, it goes down to -2,-4.
Is it possible to get an output of 8V but not charging?
For now I am using traditional bulbs. I may change for LEDs to improve battery life but would like to find out if dynamo charging can be fixed.
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Eric,
It is possible to have 8V with very little amperage, but very unlikely. If the ammeter is showing '0' going to the battery, but -2, -4 with the lights on, it begs the question "Are the generator and battery wired to opposite sides of the ammeter?" If not, then the power is not going through the ammeter, so it can't possibly give a reading.
To check whether the generator is working, disconnect the battery, start the engine with the lights turned on, if they light up then the generator is working.
Eddie.
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Per your previous instructions I wired the + from the battery on one side of the ammeter and the dioded wire (to the dynamo) and the wire to the switch to the other side.
I will test the lights with no battery.
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Eddie
I tried running the bike without the battery and the dynamo do not power the lights ! I had not a chance to measure the output out of the dynamo though.
Eric
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Eric,
Try running the engine with a bulb connected directly between the terminal at 4 o'clock on the generator and earth - this will establish whether the generator is working. If the bulb doesn't light, there is a fault with the generator. If it does light, do the same with the bulb wired to the other side of the diode and earth - to make sure the diode is wired the right way round!
If there is no output from the generator, you will need to investigate further - one of our members had a similar problem and that turned out to be a faulty magnet in the generator. I see from the photo of your generator that it is of the later type with a single full circle magnet (earlier models had 2 half round magnets). Now, this magnet should have 4 poles at 90 degree intervals. If you pass a compass around the magnet, it should show the 4 poles equi-spaced - if you get an odd swing of the compass at any other point, there is probably a crack in the magnet at that point - this will cause the generator to internally produce a rogue output that opposes the main output - thus considerably reducing the amperage. Another method is to put a sheet of paper over the end of the generator and sprinkle iron filings on to it - the iron filings will then align to show the magnetic field (just like we used to do in science lessons at school!).
Hope some of this helps,
Regards,
Eddie.
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Eddie
thank you again for your help. I have been preparing and now leaving for a 2 weeks trip to Morocco (not with the Douglas !) and I will do more testing when I am back.
Best Regards
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Well, times flies and only today I decided to work a bit on the Douglas.
I had a ride in the winter and the gears still cracks.
I removed the flywheel and measured the flatness on the clutch using the set up in the enclosed picture (sorry can not make it straight). Well I have only .010"/0,25mm of variation on the disc all around. Not too bad I guess.
I also noticed that I have a black layer looking like burnt grease on the disc. This was present the first time I opened the flywheel and I do not think they are any part of the problem.
ALso the inside of the cone is rather rough. Also not a trouble as I guess as long as the flywheel and clutch disc both truns together, the whole assembly might as well run out of round, it would not affect the clutch.
When I get the bike from Andy Tiernan back in Oct 2016, the gears did not cracked. Report from Andy also says gears goes well and do not crack.
Only after I opened the clutch, cracking appeared. So I am pretty sure I made something wrong when putting everything back together. But assembly is so simple, I can see nothing that might be wrong...
The only adjustment I have are the cable on the primary chain housing. Tightening the cable, preload the cam up to a point the clutch can slip under the kick's action.
And the springs tension plate using the nut on the cam shaft. I tried using 2 springs out of 6, then 3 then very little load.
When I had the bike it had 6 springs and, again, did not cracked.
Maybe I should use 6 springs and load the springs more?
Also I have a very light play on the cam shaft. When taking it with 2 fingers, I can feel (but can't see) a slight play. Not a concern, I guess.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180225_185501.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180225_190125.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
I had also a problem to engage gears "silent" on my S6, the reason were the 3 rollers on the clutch operating mechanism.
I change the rollers by rollers from a chain (5/8 x 1/4) and get a soft operating clutch.
May be it is worth for a look?
Michael
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Do you mean those rollers?
Are they pressed in?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180226_191729.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Yes Eric,
the studs for these rollers are pressed in.
A change is useful, if the rollers are not round anymore.
On your photo it looks not too bad.
Michael
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Yes they look nice. They measure roughly .414"/10,5mm
But I don't think using larger ones for me would help because when I pre load the cable using the adjustment, I can make the clutch slip under the kick. Everything takes me back to a too short cable travel.
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The size of the rollers is okay (10,3mm).
The ring holding the rollers has several slots to fix it to the pin on the crankcase. Chose the best position for the longest way for the clutch operating arm (to have a long cable travel).
May be it is useful to use a spring to strech the cable?
Michael
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Michael
yes there is 3 positions. But only 1 works, the one that makes the cam arm to the lowest position. Using other positions would raise the arm and the cable would be useless.
A spring is on the cable...
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I have checked what should have been probably checked earlier, that is the roll bearings and it's not nice.
I noticed that the plate was not turning smoothly and for a cause.
Some of the "square rolls" are well used.
They slightly marked the inside of the "female" part.
The part where the ball bearings are is also marked (even broken) and even though the ball seems to be above the broken lips it may not help at all. Balls do not seem to be damaged though.
I am wondering if we can get larger size bearings so we can re-surface.
Can we get parts from the club? If so I would like to get a link as I don't seem to be able to find where I can go to get those.
Did those parts are heat treated and can be machined?
Anybody ever made new parts?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180304_095647.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180304_100211.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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So nobody ever manufactured such parts?
I received an offer from a member for the bearings.
Before I can get them I need to know how we can "repair" the part or get it.
I see that I need to be a member of the Club to get parts from them. Anybody (club member) can tell me for now if these parts are available as I don't really planned to become a member for now...
Especially if they are not available from them.
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The clutch carrier sleeve is not available new, you have to find a second hand item or make it. I have made the entire flywheel and clutch, but changed the design of the bearing to ease manufacturing based on the tools I had at the time. Basically changed the two narrow groove for the rollers to one wide groove to take 1/8 needle rollers with a cage to keep them square. It was also the carrier sleeve for the thirties OHV models, which don't have the bearing balls; so not exactly the same as yours. It was written up years ago in the LDMCC's new ConRod magazine. Don't seem to have a photo on the computer, back in the film days.
It is also not uncommon to find the bore in the sprocket oval, or marked where the rollers chattered. If making a new carrier sleeve, you can make an adjustment on the diameter so you can lightly hone the sprocket true. This will help eliminate slop in the carrier sleeve bearing that contributes to clutch drag.
-Doug
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Thank you Doug
I am going to investigate in 3D printing to get a new part made unles I found an amateur that can make a new one for a decent price...
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Morning, was it the 250cc?I was in the middle of buying one from someone in the club who had a friend with one. Unfortunately, I even paid for the courier to collect the bike and the owner died suddenly the night before I was supposed to buy it.Some people said that the 250cc is underpowered, have you found this. Len
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Len
Sorry I can't tell about the 250. Mine is a 600cc.
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So after some thinking, I am going to use some new 3/16x3/16 Roller bearings as the rest seems to be in good or usable order.
The grooves for the bearings are fine. The other side is marked but I will run with it.
This should tell me if the clutch now disengage well with the clutch not being drawn by the flywheel due to poor rollers.
If it does, it will be fine. Otherwise, it will be a mess as I have no clue where can be the problem.
If the roller bearings are worn out after a while, I will have the "other side" turned out, will install 5x5mm bearings and this should work.
In the meantime as the flywheel is on "average" condition, I would like to have it refinished.
I assume it was originally chromed as it is now. However the central "ring"of the external/visible side is painted.
Was it painted over the chrome? (I can't see how they would be able not to chrome the center of the wheel...
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Well finally I will have a modern cage roll installed.
Using original 3/16 bearings on a marked and damaged outer part will leave damaged bearings in a short time.
So I am going to have this installed once for all...
I know it is not pure original system but I guess it made its time and I had no way to save it.
I did not get a reply re. this :
In the meantime as the flywheel is on "average" condition, I would like to have it refinished.
I assume it was originally chromed as it is now. However the central "ring"of the external/visible side is painted.
Was it painted over the chrome? (I can't see how they would be able not to chrome the center of the wheel...
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/A-6-TA5530-Z-IKO-FR.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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The flywheel would have been masked so that only the required areas were open to the plating process (much like you would mask up an item for painting, but using a material that forms an insulator against the electrical charge that is used to deposit the chrome plate).
Eddie.
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Thank you Eddie
That makes sense. I did not know one could mask during plating ...
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Hello friends
Finally I am having the clutch repaired with similar but larger (5x5mm) roll bearings. The modern cage was not suitable.
Anyone know the size of those 4 small screws that screws in the flywheel holding the little plate (that bears a notch to prevent the spring plate to turn)?
Seems to be 4mm(?) 25-TPi
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180326_171405.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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3/16-27
-Doug
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Thank you Doug
Any idea where to source them? I would like to avoid hours filing to make them look a little bit better.
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Eric,
Well it is not a standard thread, as you probably realize. Have you checked with LDMCC spares?
I have made batches of other 3/16-27 threaded hardware on the CNC lathe, but not had the occasion to make that particular screw so do not have any in stock. Would be a bit of a challenge to get as close to the head as they did. I have another job in the lathe at the moment; after that I might try some experimentation. Most of this stuff I have been doing in 17-4PH stainless as it is easy to heat treat so that the slots and hexes don't burr over as easy.
-Doug
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Eric,
what is that for a clutch lining?
looks like cork glued on?
Regards
Manfred
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Yes clutch lining is well cork glued in.
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Doug
I was pretty sure it was not standard even though "standard" seems to go a long way when you're talking about english screws.
And No I did not checked with LDMCC as I don't know where to go exactly and I don't have an adress for them.
I may save time, finally, straightening them with a file...
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I need to open the gear box on my Aero as I need to check why the kick sometimes seems to miss a tooth.
Is there anything special I need to know beofre I open it?
Is there any risk of having everything fell off the gear box without a chance to find the right place for various parts when re-assembling?
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Some pictures here:
https://www.douglasmotorcycles.net/index.php?topic=5595.msg20286#msg20286 (https://www.douglasmotorcycles.net/index.php?topic=5595.msg20286#msg20286)
-Doug
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Wonderful
Thank you one more time Doug
Do we need any gasket to re-assemble or shall we use a paste?
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Eric,
None of the ones I have taken apart (grand total of four) do I recall having gaskets. Nor does the 1936 Aero parts list mention any. So it looks like goo it is.
-Doug
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Sorry Doug??
"So it looks like goo it is. "
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"goo" = paste, gasket cement. silicon sealant, Yamabond, Permatex, etc.
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Hello there
I am considering having this dynamo repaired.
Found a gentleman in UK that can do it for about 400Ł
Add to this a repair I want to have made on the gear box to repair an epoxy, black patch that is plugging a hole on the top of the box and another 400Ł.
On top of the repair for the gear box bearings and a mere 280€
And a chroming of the flywheel and 110€.
I am just wondering about the insanity of the whole affair.
Can I afford it ? Yes.
Does it make sense? I don't think so.
Not asking a question there, just putting some words together to launch a discussion among the pub/bar/tavern attendance...
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Hello
I see on my front wheel that the part below can be adjusted.
I am wondering how tight/loose I want it?
Eric
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180507_182833.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
The usual setting for this type of taper roller bearing hub is so that there is the smallest perceptible lateral moment at the wheel rim/tyre.
Since the original taper roller bearings are obsolete and becoming more and more scarce, some of these hubs have been converted to radial ball bearings. Those should not have any pre-load, and ought to be re-engineered to have inner and outer distance sleeve of the same length.
-Doug
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I was wondering if this light was correct for my 19367 Aero?
No I don't plan to change it anyway.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180528_161857.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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I had my clutch back with the new bearings.
Flywheel is also back from chrome.
Center was painted black before chroming. Is that correct?
Also am I supposed to paint the inside although I don't see the need.
How was finished the back plate?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180528_150752.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180528_150639.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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The original headlamp would be Miller for 1936-38 Aeros. The shell you have looks like the Lucas wartime or postwar type.
The attached picture is the original Miller No. 74ES shell from my 1936 600cc Aero. Presumably they kept the same model for 1937-38.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/miller-74es-shell.jpg)
Flywheel. Center is painted black after chroming. I don't know if the factory masked the center during plating or not. Paint does not stick very well to chrome plating, but that might not have deterred them. Nowadays, the easiest solution is just to plate the entire flywheel. This avoids the expense of masking off portions, and avoids the accidental splattering of the mask on areas that you do want plated. Then mask off the areas to remain chrome and use a self-etching primer to get the paint to stick to the chrome. Mask and paint is cheaper than mask and plate. You might want to keep the self etching primer just a smidgen in from the radius of the rim, then overlap the black up the radius to the face of the rim. I find that this allows you to glide a razor blade over the chrome and around the rim to feather back the taped edge of the black paint without revealing primer underneath.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/flywheel-paint-sketch.jpg)
Inside the flywheel was not painted. Usually it has plating on it, but that was just incidental to the plating process as there was no reason to mask it off. Plating on the hub can mess up the fit of the carrier sleeve. Usually these are too loose and can benefit from building up, but the plating tends to be attracted to external corners and the end of the hub becomes larger than the middle. So the sleeve is tight to get on. Sometime the sleeve is mistakenly honed to get it onto the hub, only to find it as a rattle fit when in position.
What I have done is skimmed the hub and pressed on a bronze sleeve. This I turn to be a precise fit to the carrier sleeve. If the carrier sleeve is worn and needs a light hone, it allows the hub to be made oversized to suit. Eliminating any slop in the carrier sleeve and bearing will go a long way to eliminating clutch drag.
The backing plate is painted black. As far as I can tell the screws were a dull nickle plating, a standard rust proofing finish Douglas kept with into the Aero era, even when bigger items were a decorative chromium plating.
-Doug
[sketch added for flywheel painting. -Doug, 28May18]
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Thank you Doug.
Much usefull as usual.
I talked to a painter and he said that Epoxy paint must be used on Chrome. And I have that on stock.
Hopefully I can do all that during this week.
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Flywheel painting sketch added to previous post. -Doug
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Thank you Doug for the extra work detailing your explanation. It's perfectly clear now.
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Made a nice masking with tape,using a rasor blade on my lathe to make a round template.
But I learned something today, you canot sand blast, even at a mere 2 bars or chrome may peel off nickel (I guess).
So flywheel is going back to chrome (he will redo it for me for free).
Question about the front brake. The part on mypart is not from Douglas. It is adapted from anter brand.
What color is the "brake" supposed to be? Right now it is bare alminium. Should I paint it black. What were the fashions back in the days?
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Drum, backing plate, and lever are black.
Sometimes you see restorations where the backing plates are left bare aluminum and the lever is plated, but period photos through the thirties show all-black was the standard finish.
-Doug
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While preparing the flywheel for the new chrome, I thought that I may put in on my lathe to face it and remove some imperfections.
Starting at a low point where the pain may start I moved toward the center but by doing so I was removing more and more material until I stopped ending with a .3mm step.
it looks like the face is tapered with the center on same plane as the rim??
Now I am concerned about flywheel balancing or should I go ahead and remove this step?
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Eric,
Some flywheels, like that for the S6, are tapered between the rim and the hub. They start out from a recess of about a 1/32" below the rim surface and feather out to nil at the center where the clutch spring adjuster ring is. However the correct flywheel for the 600 Aero has the recess a constant depth. The rim is not the same level as the center, though. The recess is still a 1/32" below the face of the rim, but the center is 1/32" proud of the rim; so the step at the center of the recess is 1/16". The idea of the taper was to make the flywheel web thicker towards the center to better resist cracking. Later, perhaps they decided the added manufacturing complication of turning a taper was not worth the effort.
Given that your depth of cut increased towards the center, it sounds like you have a slightly earlier flywheel fitted. Function-wise, I think the whole unit is interchangeable.
I don't turn the recess. The flywheel is too thin as it is. Since it will be painted anyway, any pitting or imperfections in the recess can be taken care of by the paint primer and filler. I have skimmed the rim, as filling pits on surfaces to be electroplated is a lot more difficult.
-Doug
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Doug
Well it is too late now and the concern I have (you did not mentiond balance so it should not be an issue?) is that I have a small step just under the chrome plate (held with 3/16-27 screws) and I see no other way than going center down to erase this step. Step measured at .020"
Right now center remains .025" "proud of the rim"
You said it is too thin there so what shall I do?
Also what color for the 3/16-27 screws?
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Eric,
"Too thin" as in you don't want to make it any thinner. As you say, not anything that can practically be done about it now.
Does the step extend under the tin ring that traps the washer for the clutch springs? Basically, that is where the recess on the Aero flywheel ends. If so, leave as is. If it goes under the tin ring, well it is going to create a cosmetic gap that is awkward to fill.
Hopefully you had a slight tool nose radius when turning the recess to avoid creating a stress riser? All things being equal, if you had the flywheel running true in the lathe, what you machined off was an equal amount all the way around and you should not need to re-balance the flywheel. It probably wouldn't hurt to check the balance, to see if it was in balance to begin with.
The tin ring and the plate for the clutch springs are painted black. Or, at least they are for 1936. I have seen others that were plated, but not sure if some models used a plated ring (the same part was used from 1930 to 38 on numerous models) or the plating was done post-factory. Only the flanged clutch adjuster nut is definitely plated.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/1936-Aero-flywheel-side.jpg)
The four 3/16-27 round head screws that secure the tin ring is a little tricky. Generally small hardware was nickel plated to give a durable, rust proof finish. I cannot see in period photos four bright dots suggesting they were left plated, but I have not come across any views that are one hundred percent conclusive. But it does look as if they were painted over. On my 1936 Aero, the screws were painted (exception to the general small hardware rule) and generally the finish on the bike as found indicates it was never altered. Whether these were things they changed on 1937-38 models to make an inexpensive model change, I don't know.
-Doug
[fix broken image link. 18Apr19 Doug]
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Well I am going to try to make it nice and I will leave it this way.
Yes the step is right at the screw holes so I will have a small gap underneath the plate. It is barely visible but I like to make things nice (although I am limited by my hand's abilities).
You are right to point out the stress riser, I will make sure the step is well shaped.
The tin ring was chrome on my bike so I had it re-chromed. I shoul live with it.
As for the screws, I have an hi tech silver "paint". Iw ill use it on the screws head. It will blend better with the chrome plate.
There again I should survive with the wrong color parts !
Doug I am really glad you are available. It makes research much easier, faster and accurate. If only my abaility to work was up to the task, I would be delighted...
Thank you !
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Hello
It took me a while to work on my bike. In the meantime I had the flywheel chromed, painted and the rollers in the clutch pate replaced with larger 5mm rollers in an enlarged channel. Now the plates with rollers engages the flywheel quite tight (as it should be per the company that made the work)
I installed everything back in place.
Before
The Rear wheel at neutral on the stand was slightly turning and was easly stopped with 1 finger.
Engaging a gear made the box crack. When riding,engaging other gears was fine.
Now with new rollers.
The rear wheel is still turning but with more force. Engaging a gear is cracking a lot.
When pressing the clutch lever, I can not stop with the sole of my shoe the gear box sprocket and everything is turning at flywheel speed.
No way I can ride it now !
Clutch is disengaging for about 2mm when using the lever.
When flywheel is on the bench, launching the sprocket by hand, it goes 1/4 of a turn.
Why at neutral the gear box turns the wheel with engine running whereas when turning the sprocket by hand, at neutral, with no chain, the wheel do not moves?
Why the gear box at neutral turn the wheel with more force than it had with the old rollers?
Any help is welcome.
I am not yet quite fed up with it but getting close.
Eric
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Eric,
Sounds like the roller bearing is too tight. Unlike a typical cylindrical roller bearing, not only does it need to allow for free rotary movement, but it has to allow free axial moment as well so that the sleeve can move sideways inside the sprocket and lift the pressure plate. Or to put it another way, so the sprocket (and integral clutch disk) can float along the outside of the rollers. It is a bit of a balancing act, as any additional clearance exacerbates the problem of the clutch plate tipping (under the pull of the chain) and the periphery dragging on the pressure or backing plate. It the bearing does not have to be so loose that it drops through while static; it will be rotating at the time. But it does need to be free enough that it can float along the shaft and find a point midway between the pressure plate and the backing plate where - hopefully - it is not touching either! Velocettes are not the only marque with a fickle clutch... As mentioned the hub sleeve and the sprocket bore can be out of round. This makes it difficult to obtain the right running clearance as by the time you get rid of all the tight spots the bearing is now excessively loose everywhere else. If you have tight spots, or the roller bearing is just fitted too tight in general, you will likely also have a problem where any minute variations will cause the assembly to 'screw' the clutch disk one way or the other. That will keep the clutch disk up against either the pressure plate or the backing plate with a few pounds of force, keeping it from disengaging completely.
Also, remember the hub or carrier sleeve needs to slide along the flywheel hub freely (usually the clutch springs and your grip on the clutch lever provide enough impetus), without contributing any more clearance (allowing the sleeve and the sprocket/clutch disk to tilt) than humanly possible. The total lift of the pressure plate free of the clutch disk is limited. So if the disk or the bearing and sleeve it rides upon were to tilt, the rim of the clutch disk can still be in contact with the driven, rotating parts of the flywheel.
However it does sound from your description like the roller bearing is too tight a fit and when the clutch is released it cannot 'float' and find a happy medium clear and free between the pressure and backing plates. Indeed, the very tightness may be driving it up against one or the other. Especially your description of giving the sprocket a twirl on the bench, and it only going a part turn before encountering resistance. If you turn it the other way, does it immediately free off like the clutch disk is screwing away from contact? Can you (partially disassembled on the bench) spin the sleeve inside the sprocket without it threading itself through the sprocket?
-Doug
[Edit, the Aero clutch is single sided and does not have the pressure plate utilized on the big ohv twins. Since the term pressure plate is referenced in subsequent posts and has caused confusion, it is struck out rather than deleted. 07Aug18 -Doug]
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Doug
I guess I can see what you mean, barely (lacking again some terminology)...
I check some clearance;
The total movement of the disk in the Flywheel measured from the spring holes with flywheel on the bench (TOTAL movement) is .130"/3,3mm
The movement of the came ring from the lever/cable is .083"/2,10mm
The movement of the disk installed in the flywheel as installed and pushed by the lever/cable/cam is .080"/2,0mm
Just to make sure that this is enough.
Now the interesting thing.
When installed, no chain, I can run the sprocket with fingers and it turns freely, can make it +/-1 turn with 1 knock of the fingers. (The other day I said it was not really turning but I guess it was dragging against the pressure plate. Anyway today it turns "good")
Now If I install 2 springs with the nut barely 1 turn, the sprocket do not turn anymore when pushed with fingers. And if I turn the flywheel by hand, I can barely stop the sprocket with 1 finger.
The only think I can see is that the lip of part #13 pushes against pressure plate #6
Any other idea welcome.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/EMBRAYAGE11.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
Oops, I owe you an apology as I forgot the Aero clutch does not have the pressure plate like the big, ohv machines did. So my using the term pressure plate probably muddied the waters. I will strike that out in the previous reply.
The main thing, still, is to check that the bearing is not too tight. If without any springs installed the sprocket can be given a twirl with you fingers and it rotates freely and does not drag to a halt after a turn or two, then that sound fine. Once you start installing springs, I would expect the sprocket to start to offer resistance. Unless you pull the clutch lever, then it should again spin freely!
Referring to your illustration for item numbers: In normal operation, the clutch springs [2] press on the flange of the carrier/hub sleeve [13]. This applies pressure via the ball bearings [8] to the clutch plate [6] and forces it against the backing plate [12] to provide drive. The sprocket is along for the ride. Roller bearings [7] stabilize the sprocket and take the chain load. The bearings only come into play when the clutch plate is lifted, and allow the clutch disk and sprocket to rotate independently, and freely one hopes, from the flywheel.
When you operate the clutch lever, it uses the thrust ball race [5] to shove the whole sprocket and clutch assembly [6, 7, 8, 11, 13] sideways against the pressure of the clutch springs. Once the clutch disk is clear of the backing plate, it should be free. In the case of the Aero, there is no pressure plate occupying the void between the clutch disk and the inside face of the flywheel. This was used on the higher power machines to provide more capacity, the clutch disk had friction material on both side. So lacking the pressure plate, one does not have the problem of running out of space the lift the clutch disk. In theory if the lift were enough the back side of the clutch disk (the side not used for providing drive) could rub or drag on the inside of the flywheel. But I don't think one has enough clutch lever travel for that to ever be a problem. Also I would expect an metallic rubbing sound of aluminum on steel.
When you upgraded from 3/16 to 5mm rollers and enlarged the width of the grooves, how precise were the grooves cut?. Since the rollers do not have a cage, they rely on a nice fit in the grooves to keep them square to the race. It is not enough that they are crowded in there to keep them square.
As far as setting the clutch, you want the minimum amount of slack in the clutch cable so that you have maximum lift. I usually check it right where the clutch cable attaches to the clutch operation arm, behind the flywheel. So long as it can be wiggled in rotation just a smidgen, that is enough slack. Don't expect the thrust bearing [5] to ever stop spinning. It is enough to make sure the pressure is off it, having it idle along due to parasitic drag is unavoidable. Since the clearance is set to a minimum, you do have to check it often to make sure wear of the clutch disk has not allowed it to settle down on the thrust bearing and so bear the load; preventing the disk from bearing against the backing plate.
If the bearing balls [8] and their races are o.k., the flange on the carrier sleeve [13] should not come anywhere close to the clutch disk. It should never rub on it, or the grease slinger [11]. If the rivets for the clutch disk have been replaced by bolts or screws, you have to make sure they clear that flange as well.
-Doug
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Doug
It's much easier for me with numbers !
Once you start installing springs, I would expect the sprocket to start to offer resistance. Unless you pull the clutch lever, then it should again spin freely!
Not really. When lever pulled, the resistance is less but I can barely turn the disk with finger.
I had the rollers' groove re-cut by a company that makes bearings; I assume they know what they are doing...
I have to open it to find some marks on the metal... I am becoming rather good at it.
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Doug,
Looking at the illustration that Eric posted, it appears that that clutch would never work properly. The release bearing pushes against the face of the sprocket to lift the cork plate away from the pressure plate. That is OK but the thrust is being taken through the sprocket/clutch plate assembly and it's thrust bearing to lift the carrier sleeve against the spring pressure. That will always result in the flywheel/carrier sleeve/ clutch plate wanting to rotate as a unit instead of allowing the plate to spin free. Now, if the carrier sleeve was shortened to be just proud of the face of the sprocket, the release bearing could then have a reduced inside diameter so that it lifted the carrier sleeve, thus leaving the clutch plate free to turn independent of the flywheel.
Does that make sense??
Regards,
Eddie.
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In any case the drawing comes from Douglas owner's manual.
Should you use a smaller diameter #5 bearing then you would push #13 but clutch plate #6 would not be pushed then and remain engaged.
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No, Eric, exactly the opposite. The drive is obtained by having the springs pushing against the flange of the carrier sleeve which, in turn, pushes via the set of balls and applies pressure to the clutch plate, forcing it against the pressure plate. If the release bearing pushes against the end of the carrier sleeve, the sleeve will be lifted, releasing the pressure and the clutch plate will drift free of the pressure plate.
In your illustration, the release bearing bears against the face of the sprocket, so when the clutch is lifted, the full spring pressure is being taken by the thrust bearing between the clutch plate and carrier sleeve - this will provide enough drive to make gear engagement almost impossible. You can easily check this out by removing the flywheel and taking away the clutch release - lightly refit the flywheel and just 2 clutch springs. Use a pair of tyre levers to lift the carrier sleeve and see if the clutch plate/sprocket can be turned freely. (don't lift the carrier sleeve too much or you may dislodge some of the balls in the thrust race).
Eddie.
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Eddie,
The sprocket and clutch disk are effectively 'pinched' between the release thrust bearing [5] and the other thrust bearing under the clutch disk [8]. The idea being they are enough of an anti-friction bearing that the clutch disk can rotate freely; even under the pressure of the clutch springs. In reality, there is probably enough bearing drag that the sprocket would never entirely become stationary of its own accord. However the friction of the primary chain and the gearbox ought to counteract that and be sufficient. In theory...
There is a problem with pushing directly on the end of the carrier sleeve [13]. While this will unload the pressure of the clutch springs against the clutch disk, it does not physically push the clutch disk away from the backing plate. You would have to wait for the clutch disk to shuffle away and cease contact, in its own good time. It might just continue to drag against the face of the backing plate. Also, you would be separating the ball races for the thrust bearing [8] - perhaps by as much as the clutch lift - until such time the liberated clutch disk wandered over and closed up the gap. If I remember correctly, the races are like the old bicycle bearing type, or like the 2-3/4hp wheel hubs. There is a bit of a taper leading into the curve of the ball track. So as it separated, it would develop radial clearance. That would allow the clutch disk to hop about off center, with only the bearing rollers biased over towards the sprocket to counteract it. So I think the intention was to keep the balls of the thrust bearing [8] at all time in contact with their race.
I have ridden an Aero and an S6 with these single sided cork clutches, and they are capable of working just fine. But it is like the Douglas internal band brake, it only takes a few non-obvious things to turn them into an infernal PITA.
-Doug
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Doug & Eric,
As I said previously, "Now if the carrier sleeve was shortened to be just proud of the face of the sprocket" - I was thinking about 10 thou proud - that would mean the release bearing would lift the carrier sleeve just 10 thou, thus reducing the drag by unloading the bearing[8] before lifting the clutch plate away from the pressure plate. Set up that way, the bearing[8] would have a much easier life as it would only be performing under a lesser load when the clutch is half engaged - with the clutch disengaged, it would be running with the 10 thou clearance, and fully engaged it would be under load but effectively 'static'.
Regards,
Eddie.
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Eric,
Ah, I forgot to factor in that ten thou clearance. That would stop the bearing from separating. The race of the thrust bearing would then have to handle the differential between the speed of the carrier sleeve and the clutch disk, but the clutch disk would be unloaded from end pressure by then and the parts would be greasy. The gap would close as the clutch wore and it would gradually return to the factory design.
-Doug
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Hi everybody
Stupid here
So, as 13 and 6 were moving together no matter what and the fact that the slightest pressure from the springs was locking the sprocket, I thought that a gremlin was hiding in the #8 balls or #7 rollers.
I took off the whole thing, removed the balls and saw nothing wrong.
Counted the rollers and I had 30 on the lower row and 32 on the upper (keep in mind they are larger 5mm rollers). I was positive that I counted them 3x when installing and had the same amount of rollers on both rows.
So checked in the greasy balls, not there. Mystery.
Put 2 more rollers on the lower raw, slide the 2 parts together.
Then had one more rapid look at the balls and then I saw guess what, 1 roller in the balls. And then another one. My 2 MIA rollers were back !
A 2 years old monkey knows that a square do not fit in a circle and square rollers are probably not doing any good in round rollers.
So now I just have to slide the balls in place; Only concern is that I have 32 ORIGINAL balls. There is enough place for one more ball that I don't have; Can I roll with 1 missing?
Doug your point is mechanicaly sound (I guess) but as the parts I am using seems to be originals, I will rely upon Mr Douglas assumptions that it should work as it is.
I will keep that in mind however should I have to work on that later.
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Eric,
Don't fit the extra ball - the general rule for crowded balls or rollers is to fit a full house minus one, so that adjacent balls/rollers are not pressed together.
Doug,
Clutch wear will not affect the suggested 10 thou clearance as the carrier sleeve and clutch plate will move as a pair - only wear to thrust bearing [8] will affect that clearance.
Regards,
Eddie.
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Thank you Eddie
In the meantime I reinstalled the whole set-up as anyway I don't had an extra ball.
It works much better.
Originally when on the stand at neutral the rear wheel was slightly turning.
Engaging a gear was cracking.
Now, rear wheel barely moves at neutral on the stand. However engaging gear still cracks. When clutch is released, the primary chain still turns as you expected. Will adjust the clutch as Doug said and give her a few kilometers to see how it settles...
I don't know if the pressure on the spring is paramount here.
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Eddie,
Correct again. My brain seems to be firing only on one cylinder today!
-Doug
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Hello dear all
I had not a chance to ride the Douglas until today. Clutch still cracks a lot to engage first gear but then during riding it goes through smoothly. I will try again and maybe there is some break-in taking place.
I would like to check the head nuts.
What is the torque on these?
And what torque on gear box and engine on frame?
Also what pressure do you put in your tires. I am using 3.5x19s.
Edit :
Just noticed what may be a problem
When pressing the clutch lever I noticed that the flywheel moves.
I measured it at +.020" at 12o'clock and +0.00 at 6
Then I moved it by hand and I can definitively feel a play in the crankshaft. When moving by hand the flywheel, measured at 9 o'clock , I can get as much as .040" of play.
Is that normal or too much?
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Hello
Sorry if I appear like impatient but I plan to attend the Distinguished Gentleman Ride next sunday with 100-150 kms to do but I would like to make sure I can make it so any comment or advice about my previous questions would be greatly appreciated.
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Eric,
Never seen any torque value published. Generally manufacturers didn't for stuff of the era. You were just expected to have a feel for the bigger the fastener the tighter you could wrench on it! Basically, what you can comfortably accomplish with open and box wrenches. No sockets with breaker bars; no one had them back then.
When you say flywheel movement or play in the crankshaft, do you mean the flywheel moves relative to the crankshaft or the crankshaft moves relative to the crankcase? Either way, the numbers you mention are grounds for 'do not operate until further investigation'. The flywheel has to be rigid on the taper or the taper will be destroyed. Either axial or radial clearance on the drive side bearing is a major problem. Axial is very serious (could be the incorrectly shimmed for end play) and radial is courting a catastrophic failure. End play should be a slight 0.005-0.010" or so; in other word you should not be able to perceive it. There should be no measurable radial play.
-Doug
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Thank you Doug
Re. Torque, I tend to over tighten the bolts and nuts usually so I was just asking...
I will take down the flywheel this evening to check the play on the crankshaft and make sure from where this play comes.
I did not checked but I did not felt any axial play, only radial (from side to side)
Will come about it later.
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Well I have .030" of fore and art (axial) play
.020" side to side
Not very accurate measures taken on the crankshaft top, flywheel removed.
Noticed the shaft seems to be worst than what I remember. Should not induce play but would not help otherwise.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20180927_210455.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
To be brutally honest, with a crankshaft taper that bad, I wouldn't attempt to ride the bike anywhere! No matter how tight you get the crankshaft nut, the flywheel will work loose and do even more damage! As it is, the flywheel will not run true, so the clutch will not free properly. With the amount of play you have on the crankshaft, the whole engine needs stripping and rebuilding.
Sorry to be the bearer of bad news, but running the engine will only make matters worse.
Eddie.
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Eddie
I was ready to hear that.
I will take off the engine (and gear box as the quick tends to rattle, probably some teeths missing inside) so will hurry my winter project.
Any adress where I might go for the rebuild?
Or anybody can guide me in that?
I remember that the crankshaft has been worked on from the documents I had with the bike.
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When we'll machine the cone on the crankshaft and in the flywheel, how do we make the parts fit together again.
Is it just a matter of taking the flywheel down the cone a bit more or do we need to sleeve the flywheel?
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Eric,
From the photos you have posted and the figures you have quoted for crankshaft movement, your engine needs a complete strip down to check where the problems lie.
From the basic questions you are asking, I get the impression that you don't have the necessary expertise to do the work yourself, so I would advise you to put the work out to someone who specialises in engine rebuilds.
To bring the engine back to original spec, the flywheel taper and crankshaft taper (and possibly bearing journal) will need building up and re-machining - otherwise the flywheel will go on too far (maybe by 12mm!).
From the photo of the crankshaft taper, I would guess that someone has already made a half-hearted attempt at a repair - and in actual fact, made the problem worse, because the poor fitting flywheel has broken loose and done considerable damage to the taper. Unless you are a skilled machinist and capable of carrying out precision engineering, do not attempt to repair it yourself!!
Regards,
Eddie.
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I feel pretty confident that I can do it myself. I bought a brand new file and I don't see too much trouble in doing that while watching TV.
No, seriously, of course I will not attend to make it myself and I think I can find a local company that will make the hard work.
I guess I can diassemble the engine and maybe put it back together should I do not find an expert that can do it.
I did not knew material can be built-up.
I just hope I won't find parts in need to replacement that need to be built from billet.
You are again right about the work previously done. I will check from home tonight but I remember having seen an Invoice in the file that was crankshaft related...
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Best laugh I have had today ,nice one Eric even with that problem.
Jonathan
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The engine is now ready to leave the frame.
Only concern is the magneto. Does it needs to be timed with the engine?
Do I have to make some marks to replace it correctly later?
I went through the documents I had with the bike and several pages concern researches the previous owner made (David, owned it from 2015 to 2016)
He was on this forum and printed messages Eddie and Doug sent him.
Apparently he had troubles already with it, had it modified and it has been modified already prior to his ownership.
The previous modification was made in UK for a french owner but no name on the letter, only 2 pages of drawings and this letter.
Will try to sort this out over the week-end.
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Well I have sorted out all the documentations that came with the bike.
However some documents are not dated so I am not sure at what time the crankshaft has been worked on and if several modifications has been made or if it was just discussions.
Anyway I will have to remove and open the engine. So this takes me back to my previous question about Magneto. What is the trick to remove it without loosing the timing or if it is just a matter of re-timing (with professionnal help) upon re-assembling...
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Eric,
There is no way to practically preserve the timing unless you want to do paint dots on the gears or scratch marks. It is just simpler to re-time it when it gets put back together. Given the other issues that have arisen, I would assume the timing needs verifying anyway, so might as well go through the procedure yourself and know it is set correctly. There might well be marks by the teeth for the valve timing already, though unlikely for the mag. But it is not that complicated to time, so I wouldn't worry about making any special marks.
-Doug
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Engine is now on my bench.
Anybody can take me on a step by step process to reach the crankshaft please?
Is there and caution To have when disassembling like on the valves?
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Thanks To the manual I managed to remove 1 cylinder. To get the second one I need an imperial Allen wrench which I did not have here.
I noticed some extra grease near 1 valve?
The brass part near the oil pump is not nice but seems to work.
Piston is scratched but cylinder is nice and rings has been replaced by previous owner.
Now the manuel do not enter further disassembling so I will need help from now.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181013_183800.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181013_183810.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181013_183857.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181013_184005.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181013_184013.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
Don't know what the grease is about. The tappet chest should be lubricated by oil mist.
Splitting the cases is pretty straight forward. The only thing that needs special mention is to remove the timing pinion before tapping the crankshaft through. It can be a tight fit on the crank and difficult to get behind it to extract. You might need a special gear puller. The crankcase wall is very thin behind it, so you don't want to be prying against it, or using it to strip the gear off the journal. I cannot remember if the key for the pinion will clear the hole through the crankcase wall, so you will need to check that and extract the key, if required. The ball bearings should be just a light tap (with a rawhide mallet) fit in the crankcases. If stuck, a little heat around the bearing bosses should free it up. If the crankshaft slips out of the ball bearings, leaving the bearings in the crankcase, then just leave them there. Unless the bearings need replacing. On the drive side, there should be a bearing slinger between the crankshaft and the bearing. Between the bearing and the crankcase there may be one or more thin shims that set the end float. Again, it depends if the crank slips out of the bearings, or the bearings slip out of the crankcase.
I seem to recall form older posts for this machine that the oil pump drive is slightly different for the 1937-38 machines, vs. my 1936 Aero. For 1936, the worm has a bronze bush and spins on a steel post that is pressed into the timing cover. For 1937-38, the arrangement was the worm was on an axle, and the bush was in the timing cover. Though I am not sure why the bore is offset so much from the original hole in the timing cover. maybe they needed to alter the location, and that was the easiest way to do it.
Cylinder wall oiling is basically the spray tree from the oil pump dribbling oil in the path of the conrods. This is supposed to line up with shallow grooves in the center web that lead the oil in at the sides of the conrods and so to the big end bearings. See arrow in following image:
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/Aero-crank.jpg)
What misses the grooves get splattered about by the crankshaft and thrown on the cylinder walls. So you will want to verify the spray tree is delivering oil, and that the holes are approximately lined up with the grooves in the center web. Because it looks like there is a problem with the pistons not getting enough oil.
-Doug
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Doug
since the picture I removed A Nut and B part. I guess the Timing Pinion is what I marked as C.
As for the Bearing Slinger and Shims. I don't saw any shim and I have only 1 washer marked E. No idea what is a slinger. SEE NEXT MESSAGE FOR MORE
As for the spray tree, it points above the conrods but I can not see for now where is the center web from your picture??
For now it looks like there is an anormal play at F. The nut might be not tight but I don't have the right wrench with me.
Bearing on Shaft exit seems OK.
Is it an original set up so far? (except oil pump arrangment)
Do you have any tip as how to test the spray tree?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_122615.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_122650.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_135327.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_120445.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_120435.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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OK I finally went the whole thing.
I did not find anything really wrong in the bearings, plays or whatever except the play on F described before.
Now I found a home made washer which I really do not like and the wall behind it is cracked and out of shape. (do not seems to be really flat)
I met a company in Birmingham last year that can repair this crack. At least I am going to ask him as the wall is only 3mm thick...
Unless it would be better to machine and put a steel insert?
The red arrow shows a slight mark that do not seem to be a crack.
Would you please confirm the valve cams are on the right position as I did not made marks on them and I need to make sure they do not rotated 180°. I don't think so but want to make sure.
Any other comment is welcome.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_181322.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_181339.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_181435.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_181441.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181014_182302.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
Yes, "C" is the timing pinion. It will need to be withdrawn, and possibly its key, before removing the crankshaft from the crankcase/bearing. You will probably have to remove the cam spindle support plate "D" and the inlet and the cam wheels to get good access to the pinion. To get the cam wheels off, you will need to remove the tappets for the rear cylinder that are blocking the way.
There is a keeper plate bridging the two tappet guides, which is pretty obvious. The tappet guides are tapered on the outside and usually need a tap with an aluminum drift to pop them loose. The head of the tappet is too big to exit with the tappet guide, so the tappet guide is slid off the tappet. That means the valve adjusters have to be removed. Once the tappet guide is slid out, the tappet can be cocked at an angle and withdrawn to the inside. A bit of a nuisance, but it makes for a commendably compact arrangement.
"E: is the oil slinger i mentioned. It looks like it was in the correct position, between the crankshaft and the drive side ball bearing. The shims (if any) are behind the bearing; between it and the crankcase. They can stay there until you determine if the crankshaft end float needs adjustment.
"F". The connecting rods can have a little end play with out detriment. I don't know what the official amount would be, but in general 0.008 - 0.015 inch is often encountered for roller bearing connecting rods. I would err towards the loose side because the Douglas crankshaft does flex and you do not want the connecting rod getting pinched! This gap can be checked with a feeler gauge. The bolts that hold the whole the three parts of the crankshaft together should be very tight. You do not adjust the clearance by how much you tighten the bolt, the assembly had to be clamped up solidly and rigid. If not, the flex and motion across the connection will eventually work it loose and fracture the crankshaft.
You will want to check the connecting rod bearings while you are at this stage. They should rotate freely in either direction with no tight spots. Axial clearance as already noted. You should not be able to feel any perceptible radial play. This can be done by spanning you thumb across the connecting rod and crankshaft web and applying pressure and trying to feel any relative movement between the two. Don't take the crankshaft apart unless you have to, though it may be require to repair the crankshaft taper.
Spray tree/bar. It looks like the end of your pipe is open; it should not be. The end should be capped with weld and there will be two small holes pointing down at the crankshaft. It is a matter of checking to see if these holes line up with the grooves in the center web that led oil into the connecting rod bearing. A good time to check it is while the crankshaft is still in the crankcase and can be revolved while making observations. I don't think there is enough volume of oil that it jets out of the hole, so there is no point trying to test the system under pressure. It is more like a dribble in the path of the crankshaft. The spray bar is threaded into the pump body and locked by a jam nut. Axial adjustment is by threading it in or out of the pump body in increments of one revolution and locking it in place with the nut.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/spray-bar.jpg)
At some point, you will want to check that you oil pump is working. That can be done applying some oil to the inlet port and turning the pump over by hand. Oil should be transferred to the outlet. The oil circuit has been dealt with in other posts.
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Doug
I assume you replied "only" to the first part of my message.
The spray bar is well closed on the end.
The play at F is like if the large bolt is not tight enough.
I don't have any play at the conrods. Well not so much that I felt it but I have to remove the piston to feel it better.
The only "shim" I found is this homemade washer.
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Eric,
You posted another reply while I was typing the last message, so it did not address the latest developments.
If the bolt for the crankshaft were not done up very tight, or the joint not pulled up hard against the shoulder of the crank pin race, that would be extremely detrimental to the rigidity of the crankshaft.
Typically there should not be a washer behind the crankshaft pinion. Standard design practice would have this pull up directly against a shoulder on the main shaft. However... The spares list does state part number "18022, Washer behind pinion". So it looks like there is indeed supposed to be one there.
The inlet and exhaust cam are the same part number. So it does not matter which position you install it, or which side faces in; other than the generally good practice of returning everything to its original position because the parts have bedded in against each other.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/20181014_181435-edit.jpg)
The cracks at "A" are typically due to levering off the timing pinion by prying against the rear wall of the crankcase. Folk do not realize how thin it is. As long as there are no lose pieces, it is best left alone. Welding will likely make it much worse. Douglas aluminum (or alumininum) has a very poor reputation for welding and is to be avoided if at all possible. It is very porous, and well saturated in oil. This creates unending impurities when welding regardless of the skill of the welder or how modern their equipment. It is never pretty and often cracks alongside the weld. Plus, you have distortion issues caused by welding. All that is needed is enough of a lip to stop the ball bearing from pushing though into the timing chest. Indeed, part of the crankcase wall is already removed to allow oil to breath into the timing chest at the port "B". So these cracks are relatively harmless.
More worrisome is the crack at "C" as this ties the main bearing in to the rest of the crankcase. And I cannot see how it can be anything but a crack as it spans the machined and cast surfaces. It is peculiar, I have to admit, that it does not seem to penetrate through to the inside of the crankcase. The saving grace is that it is above the bearing and not directly in the load path between the bearing and the cylinders. Still, it is a damnable thing. Do you leave it and hope for the best, or gamble with welding and the problems associated with that?
You could bore it out and put in a steel sleeve. The following is just such a repair carried out on a 350cc crankcase.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/A31-crankcase-repair.jpg)
In this case the entire wall was blown through because the timing pinion was not removed first before extracting the crankshaft. This repair does not really tie the bearing housing into the crankcase, but it does help distribute the load. The saving grace is it is only a 350cc, so the load is not as great. Mind you, the 600 Aero probably only makes 12-15hp.
-Doug
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Doug
I forgot a shim. I had well one bearing against the crankshaft larger diameter and the face of the bearing. Side opposite flywheel.
As for the inlet/exhasut cam. Depending how you rotate them, their face can be / or \ hence my question.
Re. the repair, Nicolas Hood makes repairs without welding. They have a special process with screwed in parts and remachining. www.castingrepairs.com
But as you said it does not need repair, I will leave it. I will wait Nicolas' reply though.
As for the crack on C, I checked it again and it is definitively not a crack. It is just a surface mark although I can't explain its origin.
I tried to tighten the large crankshaft nut. A socket won't fit so I have to use a flat wrench. However 28mm is too large (being 28,1mm) even if bolt is measured at 28mm and I don't want to force as it is likely to slip and damage the head which is already not nice.
What is the actual size of that bolt?
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Eric,
The following timing info is for the 600EW, but basically the same engine design as the 600 Aero.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2017/600EW-valve-timing.jpg)
I do not remember what the crank pin bolt size was. Most likely the hex is a Whitworth wrench size. The next size under 28mm is 9/16W, which has a maximum distance across the flats of 1.010 inch. 5/8W is 1.100 inch.
-Doug
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Doug
Can you educate me with 5/8W (it looks like it is not 5/8") that makes 1.100".
That is 27.94mm so it might well be the one.
Beside
I have hex nut bolts and Allen bolts on the cylinder heads. Which ones are correct, where to get them and what size are they?
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Eric,
Whitworth wrenches are a peculiar British institution. Not only did Whitworth pioneer a standard for thread sizes and pitch, but also a suitable size hex head for the bolt. I do not know how he came up with these 'optimum' sizes, as they are all odd sizes (not fractional or metric). This all back in the day of wrought iron and coarse threads. So a 5/8 Whitworth wrench would be suitable or a 5/8 bolt (or thread diameter), with the hex head of course being bigger than the bolt shank. Over time, bolts transitioned from iron to steel and material-wise were more homologous; also a fine thread series (BSF) was needed. So British Standards (BS) which took over for Whitworth (now relabeled BSW) reduced the hex height and increased the hex size. The modern, low profile hex head bolt. This lead to a disconnect between a Whitworth wrench, and the bolt head that it would fit. What was formerly a 5/8W wrench now became a 11/16BS wrench. You will find tables for the wrench sizes online.
I am not sure when internal hex head bolts (Allen cap screws) first came into use. Douglas did use them on the post war models, but you will not find any on the prewar bikes. The cylinder head bolts are 5/16-18 Whithworth thread. The dimension across the hex is 0.437 inch, or 7/16. Not a Whitworth wrench size. I don't know why they chose not to use a Whitworth size (0.445 inch).
-Doug
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When I started with the Douglas I had to learn the subtles of the British "Standards" and I even wrote a piece on a french forum on the subject but I never heard that Witworth also "standardised" Nuts dimensions !
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I removed the pistons. Checked the play on the rods. Nothing wrong here.
I made my own 5/8W wrench and the flywheel side of the shaft can be tightened almost 1 full turn and I did not forced.
So I will have to find a way to make them tight and maybe Loctited?
On the center web, I have a small screw. What is it for?
Next step is to check for plays on the bearings and then go to a machine shop with flywheel and shaft for rebuilding of the cone connection.
I have 1 piston full of carbon on top and the other one only covered on a 1/3. Any meaning here?
I will re-do the paper gaskets. Previous mechanic that did them made a nice and tight fit around round parts (cylinder bases for instance). What is the trick to cut round holes in paper gasket, at the right place?
Pistons are scratched but the cylinders are nice. I guess they are ancient scratches but will check spray tree though.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181017_182256.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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While the engine is in parts I will make some paint.
Do I have the correct color scheme on the drive train?
Do I have correct gas and oil hoses?
What improvements would you recommend?
How would you "sand blast" the cylinders?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/P107023111.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/P107020811.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
The slotted screw on the center web of the crankshaft is a plug for an oil gallery. The 1936 Aero engine was derived from the 1935 500cc "Blue Chief" 500cc Douglas. The Blue Chief had a drilled crankshaft and oil pressure feed to the end on the crankshaft on the timing side. I would appear you have a Blue Chief crankshaft in your Aero. If so, the crank does not have the shallow grooves leading to the connecting rod bearings and the spray bar oiling is not going to lubricate the big end bearings correctly.
The tappet chest covers, dynamo, and entire intake manifold were painted black. No bare aluminum. The copper hot air tube for the carburetor is a facsimile of the original, which was chrome plated steel. The end had a small flare. It extended to the top of the cylinder head, not past it.
The oil lines did have a short segment of flexible hose. The original furrels are a little more rounded on the ends than modern ones. The rubber was not black, but a blue-grey color.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/Aero_flex-2.jpg)
This must have been something common at the time, because the handlebar grips exhibit the same blue-grey color. Note the ends where the grip was protected from the elements:
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/grey_grip_2.jpg)
-Doug
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Eric,
Original 1936 Aero 600 oil lines.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/Aero-oil-lines.jpg)
Somewhere I should have the fuel line, but I cannot lay my hands on it at the moment.
While the following advert dates to 1937, it shows a 600 Aero in the 1936 petrol tank scheme so must be a left over model.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/1937-Aero-Pride-and-Clarke-advert-1.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/1937-Aero-Pride-and-Clarke-advert-2.jpg)
Pride & Clarke were advertising the Douglas line as early as April 30th 1936 issue of The Motor Cycle.
-Doug
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I went and checked some details.
- The tree is well adjusted. 2 ports are facing right on each edge of the center web.
- Bearings are turning smooth with no play I can feel.
- Same for Conrods. Only a little barely feelable axial play.
- Tested the oil pump. Oil fed through the bottom port went down through the bottom plug. Then I put oil on the top port and turned pump the other way and oil dropped from the tree.
So I guess it's a pass.
- Checked play on the crankshaft :
- No play on Flywheel bearing
- LARGE play on the middle bearing like several millimeters
- When crankshaft is sled through BOTH bearings, absolutley no play I can feel (see picture below)
- When oil pump end is fitted, no play either of course.
Now some questions.
1. I made pictures of the marks that tappets are making on the valves. Is the pattern normal or does it tell anything?
2. What shall I do with this homemade washer. Should I make a plain washer of the same thickness?
3. How to lock the big nuts on the crankshaft? Loctite is required and is it enough?
4. I have more carbon on top of 1 cylinder than the other one. Any meaning?
5. Can I sand blast cylinders to paint them?
6. What was the finish on the aluminium parts? Polished, blasted, brushed?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181020_163302.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
Sounds like the oil pump and the spray tree/bar is o.k. However if the center web of the crank does not have the shallow grooves, the oil is not going to be able to get into the connecting rod bearings as it ought to.
You will need to be more specific about the clearance in the 'middle' bearing. Is the play in the bearing itself, that is between the inner and outer race? Or is the play in the fit between the bearing and the journal of the crankshaft? Either way, it needs more investigation as it sound like something is amiss.
The long timing side shaft, apparent lack of oil grooves on the center web, and mention of a 'middle bearing' (implying there are three) make me think you have a 1935 crankshaft in a 1936 engine. Have a look again at the photo I posted of my 1936 crankshaft. Note the timing side shaft is short. It ends at the nut for the timing pinon.
Also it contains the answer to your question about crank pin bolt retention. There are supposed to be a tab washer under the bolt head.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/Aero-crank-2.jpg)
1. Marks of the heads of the tappet adjuster from the tip of the valve stem. Normal.
2. Make a new washer, but keep the outer diameter smaller than the root of the gear teeth. The spare list does not say how thick the washer should be. So copy what you have, or try to figure out what the optimal thickness would be to bring the face of the pinion flush with the rest of the gear train.
3. See above.
4. Simplest answer is that piston (and rings) were passing more oil than the other. Be it scoring in the cylinder, rings tired, excessive ring gap, ring flutter, or all the many things that lead to excessive amounts of oil getting past. De-coking engines was a fairly regular ritual back in the day. We are rather spoilt by modern engine in comparison with better air filtration, lack of dusty roads, and lower mileage on vintage machinery as to expect never to do need to scrape carbon. Having said that, both pistons should carbon up at about the same rate.
5. Yes.
6. The aluminum seems to have been 'smoothed-off' at the factory. Or at least in the areas where readily accessible; they did no go into every nook and cranny. Nor did they bother on areas not readily visible, such as underneath. I don't think it was polished to a mirror reflection, more of a satin finish. Most likely it was a job given to the apprentices, so the amount and diligence likely varied from motorcycle to motorcycle. As previously mentioned and shown in the adverts, much of the timing side face of the engine was painted black.
-Doug
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Doug
The center web has well the oil grooves machined.
As for the play in the middle bearing, It looks like the shaft bears on the aluminium frame, look at the marks on the shaft. So that's where it pivots around.
Bearings measured with a caliper at 24.9mm, shaft measured at 25mm. So considering mesuring internals with a caliper is not accurate it is a good fit.
So it should not pivot???
The pictures shows the shaft entering the bearing but not in place yet.
Shaft is much longer than on your picture. However how would the short 1936 shaft would fill the difference in length?
I have not removed the nuts yet but I don't think I have lock washers? Where can I get them?
What are those aluminium cages on your picture?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181020_190658.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181020_190409.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181020_190610.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
The grooves are deeper and narrower than what the factory used. Someone has modified the center web to work with the 1936-38 oiling system and the spray tree. At least the rod bearings will get oil.
Because the 1936-38 engine uses a spray tree, it does not need to introduce the oil via the end of the crankshaft. That is why the shaft does not need to extend all the way to the timing cover. Nor does the 1936-38 crankshaft require internal oil ways. This probably explains the strange, offset bush in the timing cover. It was part of the modification to install the 1935 crankshaft in a 1936 engine.
The crankshaft stops at the engine pinion nut. The nut has a pair of drive dogs for the oil pump worm. The oil pump worn spins freely on a dowel pin pressed into the timing cover, coaxial with the crankshaft, of course. A picture looking into the timing chest and a view of the inside face of the cover.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/600Aero_timming_chest.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/3-stage_pump.JPG)
Now having said that, I do recall from a prior post that there was some differences noted between the 1936-37 and 1938 engines. Specifically, the 1938 engine the worn has a key. In my engine, no key is required. So perhaps they did extend the timing shaft back to the timing chest, though I am not sure why they would bother. They had a lot of other engines with the 'short' shaft and they never seem to have been a problem. I have a 1938 spares list, but while I have seen the 1936-37 spares list, I do not have a copy of it.
As I mentioned, typically there is no shims or bearing spacers on the timing side of the crankshaft, but again, perhaps this was a requirement of using a different crankshaft in the crankcases.
You probably will not find tab washers the right size. It is a small bolt diameter with a large hex head; an unusual combination. Most likely you will need to make them.
The aluminum cages in the photo I used are the roller bearing cages for the connecting rods.
-Doug
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My shaft being supposedly a 1935, it is however not hollow !?
The worm driving the oil pump is on the main crankshaft on top of the timing pinion and locked with a nut. Then the remaining of the shaft goes in this bronze bushing in the timing chest.
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Eric,
The crankshaft being 1935 was a possibility. However, as mentioned in the last email it is known from the 1938 parts list that there is something different about the oil pump worm compared to the 1936-37 models. Perhaps the crankshaft is different also, and that it is a 1938 crankshaft fitted. Unfortunately, I do not have an example of the 1935 crankshaft or the 1938 to compare to my 1936. Nor have I seen an example of these components so I have to go be indirect observations.
I do know the 1935 crank fed oil in via the end of the crankshaft. But I do not know if this was via a plain bearing in the timing chest or via an oil quill; they used a quill on several other models. It also used a duplex gear pump at the base of the timing chest. Since your crankshaft does not have a hole drilled in the shaft communicating to the throw (not hollow), it would suggest it is not 1935. I know from mine it is not 1936. Though I do not have a copy, I know the 1936-37 models are covered by a single spares list, suggesting the 1936-37 models were the same. I do not know that for 100% certain, since I do not know the contents. They did issue a new spares list for 1938, and I have a copy of that. But without the 1936-37 list, I cannot compare the part numbers to see if the crankshaft part number changed.
My best guess now is they decided to extend the shaft for 1938 to the timing chest for additional support via a bush, but not necessarily to provide a means of supplying oil via internal drilling. Why they did so when they managed without this additional support since the basic design was introduced with the 600EW in 1927 I have no idea. Nor do I know why it would then have a plug in the crankshaft web, suggesting a cross drilling for internal oiling. Until another similar example turns up it is a bit of a mystery as to what year it is or if it is a mixture of parts from different years.
-Doug
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Addition pictures of the 1936 timing cover for comparison.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/DSC08150.JPG)
And a closer view. Note no provision in the casting for a bush (indicated by arrow), or gutter to collect oil the bearing.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/DSC08151.JPG)
-Doug
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The 1937 Aero 600
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/1937-Aero-600.jpg)
Curiously, the cylinders appear not to be painted black.
The 1938 Aero 600
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/1938-Aero-600.jpg)
At some point in 1938 they apparently ran out of cast lugs for the saddle springs and substituted a bit of steel tube with the ends flattened! It did the job and was much simpler (and cheaper). I have seen it on a few late Aeros, so not just a one-off.
Back to your engine, Eric, I wonder what the serial number would indicate what year it is?
1935 Blue Chief (probably ruled out by now) would be 5/H***. A crankcase from the similar Endeavour would be 5/J***.
1936 would be 5/L***, 6/L***, or 6/M*** for the 500 and 600cc models. Not sure what the difference between the 6/L and 6/M is.
1937 would be 6/P*** or 6/PM***. Again, do not know the significance of "M".
1938 would be 6/Q***.
-Doug
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Doug
here are the serial numbers of the bike.
Eric
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/P1070214.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/P1070212.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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1937 frame, 1936 crankcases, and crankshaft and timing cover??? The mystery continues!
-Doug
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Doug
it is confusing what this bike is. Some kind of Frankenstein's bike maybe.
In any case my main concern is to have it back on the road now.
I considered checking with a local company to repair the cone on the flywheel and crankshaft but I did not had a chance to visit them yet.
In the meantime I was wondering if I should check with a UK based company that may be more used to this kind of work. If anybody has an address to share?
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Eric,
Douglas changed a only a little bit from one year to the next year (most of the time), so there is a lot of parts interchangeability between years.
I was thinking some more on your description of play in the one crankshaft bearing. Douglas typically used a double row self-aligning bearing on the flywheel side.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/SKF_selfaligning.jpg)
It looks like they continued this practice into the Aero models, judging by what I took out of mine. If so, then being able to swivel the crankshaft around prior to it engaging the second ball bearing is normal. While you still can get the double row, self-aligning ball bearings, it is much more durable to use double row, self-aligning roller bearings. Those were not available back in the day, but it is what I use today in my Douglas engines.
I think the theory for using the self aligning bearings was Douglas knew the crankshaft was going to whip about. Rather than try to resist it and perhaps crack the lightly constructed drive side crankcase wall, they allowed the crankshaft some freedom under the assumption it was more likely to spring back!
Welding up of the taper on the ohv Douglas crankshafts has not always been successful. They tend to break where the weld stops. However, the side valve motors produce significantly less power, so it is probably worth trying.
-Doug
[Fix typo. 23oct18. -Doug]
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Doug
the plan was to check again this bearing after work so your message arrived right in time.
I used a piece of metal that slide just tight in the bearing and there is well a side play induced within the bearing. Of course it does not move as much as in your illustration and shouldn't you post this note, I would have said I had a problem with the bearing.
When the shaft is in place, it does touch the aluminium frame only when the shaft is pushed from side to side.
Considering the marks I have on the shaft, I would say the shaft does not turn true, the "self-aligning bearing" does his job and the shaft rubs against the aluminium and makes this small shiny mark.
We should be fine there too?!?
As for the tapet chest covers, the parts I have are chromed (should be black) and they are plain steel, like 1/8" thick. Are they the right parts? Gaskets are made of some kind of rubber and are the same size as the cover. Being held in place with just 1 screw, I can not see how a circumference gasket could make it.
Is there a relation between the loose crankshaft and the shattered cone on the flywheel?
Now to summarise the situation
1. I need to make tab washers for the nuts. I will double this with Loctite.
2. Need an adress to adress the flywheel cone or I will go locally
3. Will try to make a new washer to replace this strange washer I have behind the timing pinion. Isn't it an oil slinger there too?
4. Source engine head bolts. The only one I found for now are those below 5./16W -18 Tpi
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/catalogue_images_074_6.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Good evening all ,I have been watching with interest. How much metal needs putting back on the taper and is the crank material suitable for hard chroming and then grinding. I have had small marine gearbox output shafts done this way ie 1 1/4 " dia over a length of 3". just a thought
Jonathan
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I've also had gear box shafts built up with an electroless nickel process and found it satisfactory. They required I grind the shaft well undersize to the necessary surface finish first and they then built it back up to size using their process with no further work required by me. I was impressed by the precision of the process.
I suppose what Jonathan and I are saying Eric is that there are other ways of repairing the crankshaft taper which do not necessarily involve welding. It's worth checking them all out.
Unfortunately I've never yet found a system that doesn't require the firm application of a thick wad of cash to to get a result.
-
Hard chromium electroplate (versus decorative chromium electroplate) has been used on DT crankshaft tapers with poor results by the late Phil Manzano. Eventually the crankshaft broke at the top of the taper where the plating stopped. It is impossible to ask now if the crank had been baked to minimize hydrogen embrittlement resulting from the electroplating process, though I would have though Phil to be aware of that with his engineering background. At the time it was felt to be a combination of a stress riser where the plating stopped, and well as the very low coefficient of friction that the chromium plated surface had. This low surface friction made it impossible to stop the flywheel from 'shimmying' slightly on the taper even though the joint was lapped, and the added shock loading may have contributed to the premature demise of the crankshaft.
But as mentioned before, the power of the 600 Aero is no anything like a tuned DT, so plating (or welding) may well be o.k. But if you do go with plating, make sure the firm doing the job takes steps to minimize hydrogen embrittlement. If they have plated springs and other hightly stressed parts, they probably already know all about it.
-Doug
[fix typo. 25Oct18 -Doug]
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Eric,
The tappet chest covers are aluminum castings-
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/DSC08153.JPG)
They are flat on the outer face, but there is a raised boss where the bolt passes through. Also, the edges are well radiused. On the inside they are ribbed. Notice also, even though the inner face is recessed, there is some light milling to make sure the head of the tapper adjuster screw does not touch the cover (on the left side).
The original bolt will have a very small Kingswood trademark, unless it has been polished away.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/DSC08154.JPG)
I have an old stock gasket set, but I do not know who the manufacturer is, or how accurate the material thicknesses are. But the gaskets for the tappet chest covers is a thick pasteboard type material, 0.070" thick. The gasket abuts the crankcase on one side, so rotation is not a problem. Yet it could slide downward, but I guess it was expected to stay tight. After a short while, the gasket probably deformed to the edge of the cylinder casting and that helped keep it in place. Perhaps the factory gasket had a horizontal crossbar across the middle with a hole for the bolt that kept the gasket from dropping down and these aftermarket gaskets I have are a cheap replacement?
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/DSC08157.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/DSC08158.JPG)
I looked in the 1938 spare list and they do call out an oil slinger for both the flywheel and timing side ball bearings.
The self-aligning bearing is to allow the crank to flex at elevated rpm, but the main journals should run true. The self-aligning properties are not to accommodate a bent crankshaft. If the crankshaft is bent, the rod bearings are going to have a tough time and you will also likely experience piston seizures due to the pistons being crooked in the bores and developing hot spots.
I made new cylinder head bolts for my engine. Actually I made them several times over. The originals were quite rusty, so I decided to make new ones in polished stainless steel some twenty-five years ago when I first got my '36 Aero. The place I just started working at the time had a CNC lathe and specialized in stainless steel parts. So I made some out of 304 grade stainless, as I did not think the original bolts were made out of anything special regarding strenght. When I tightened the bolts, I noticed they never did pull up tight but just kept turning, and turning , and turning... I took the bolt back out and the 5/16-18 Whitworth thread was 5/16-16 pitch where the thread exited the tapped hole! :( I had underestimated the small (and weak) core diameter of the coarse Whitworth thread. Fortunately it did not mess up the thread in the cylinder. So I made new bolts out of 420 stainless steel and had the fella at work ruin them through the heat treat furnace. Those ended up so hard they were brittle, and the heads popped off one after the other. :( I suppose the fella could have heat treated them to a lower hardness, but he only knew one process for each grade alloy and for 420 it was dead hard all the way through! Finally I made them out of 17-4PH stainless, which can be heat treated without getting too hard and brittle (about 46 HRc). I don't think the original bolts were plated, I would have to search them out and check.
Recently I made some for my F28 (1928 600EW) that are also 5/16-18, but a different shape to the head altogether.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/F28-Douglas-bolts.JPG)
There may be a relation between the loose crankshaft and the torn taper. If the crankshaft is jerking about the flywheel is going to be jarred and that will only encourage it to become loose on the taper. However, a poorly fitted taper is sufficient in itself to work loose and start fretting and scoring the surface. Mind you, a loose crankshaft is a catastrophe just waiting to happen.
-Doug
[Strike out comment about tappet adjuster clearance, see subsequent post. 24Oct18 -Doug]
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When reinstalling the tappet covers I noticed that the heads of the adjuster screw do not even come close to the joint surface. So why the one tappet cover has a little extra clearance milled on the inner face, have no idea. Previous post edited.
-Doug
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Using the enclosed set up I measured the crankshaft for trueness.
Results are not exacts due to my ability to measure and the condition of my lathe.
A = .005-.007
B = .009 - .015
C = .009 - .013
D = .005 - .007
E = .005
Is that good enough or not?
I did not applied too much of a pressure to hold the shaft although when I did it I did not paid attention to that...
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181025_154808.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
It is impossible to say with that setup. You do not know if you are reading run-out of the crankshaft, or run-out of your mounting in the chuck or the tailstock center; or a combination of all the above. Three-jaw chucks are notorious for not being very accurate. You would need to get the chuck and the tailstock ends indicating zero run-out for the values at A through E to be directly meaningful.
If you were able to get each end running true, the typical number often quoted for two-bearing motorcycle crankshafts (usually single-cylinder engines with full dish crankshafts) is no more than 0.002 inch total indicator reading at the bearing journals.
I have not seen a factory value specified for Douglases. They only stated "Return the crankshaft to the Works for service"!
-Doug
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Hello
today saturday 11/10 I went to the Epoqu'auto show in Lyon, close to home.
I met there several companies that could repair the cone on the flywheel/crankshaft.
One young chap seemed to me to be more inclined to make a good work.
He owns a company making general machining and just set up a new company to build pinions and he's a biker.
He suggested (and indicating a company that could do it) to have the parts welded to add material and he would re-machine on top of that.
He talked about a nitrure surface treatment (not sure of english name on that) after machining. Is it a good idea or will this led to fracture points?
He said that the welding company might be able to match the RC of the original part which sounded a good idea.
Do you have (Doug?) the factory dimensions of the parts there. He can measure them with accurate lab style tools but I am a little bit concerned that the condition of my parts may not allow to make accurate measurements or the flywheel might even crawl too much on the shaft.
I will get back to the show tomorrow 11/11 so I can ask him more even though I still can reach him after the show of course...
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Eric,
This is the specifications for the 1930 S6 crank taper, but I believe it is the same for the Aero.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/crank-taper.jpg)
Dimension in inches. On the flywheel side the diameter at the face is 1.160 inch, a little less than the full journal size of the crankshaft.
Not all metals can be nitrided, so some careful attention to the weld materiel will be required. The tempering temperature for crankshafts was generally around 760C 600C, so nitriding temperatures of 550-575C for gas nitriding should be safe. The rest of the crankshaft will need to be masked to protect it from nitriding and oxidation.
Probably the greatest risk stress cracking is from the welding itself, rather than the nitride hardening. Nitriding is typically a shallow treatment, nor do you require much depth for the flywheel taper. You just need a hard skin to resist fretting and galling. Since the nitriding adds an additional cost, you may want to investigate welding up the taper with a hard facing material and forgo the nitriding. Stellite or manganese steel are two possibilities.
-Doug
[Correction to tempering temperature. 760C used on OHV crankshafts, 600C used on side-vale crankshafts. 11Nov18 -Doug]
[Fix typo. 08Dec21. -Doug]
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Correction: lt looks like some of the side-vale cranks were tempered from 600C. Still above the nitriding temperature.
-Doug
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While the engine is out of the bike, I will have the dynamo refurbished so it can (maybe) charge the battery.
In 2013, previous owner had an invoice for "BTH M2 CAM RING"
Any idea what this might be.
I have been asked by the re-furbisher if the regulator was inside the dynamo or separate. He needs it so I need to find it but I have no idea what to look for.
-
Eric,
"BTH M2 CAM RING" is a ring in the magneto that operates the points.
The dyno does not have a regulator. Trust me, overcharging is not a hazard with the BTH pancake dyno! :) There is a BTH cutout that attached to the frame using the nut that holds the post for the hand change lever. This is what the cutout looks like, but the correct bracket is a triangular affair of flat sheet metal.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/P8040001.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/P8040002.JPG)
You can just see the bracket attached to the frame in this picture.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/scan0101a.jpg)
-Doug
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I do not have a BTH Cut out. There is nothing screwed on the gear level post.
I do have a diode on the wire from Ameter to Dynamo though.
I guess it's doing the same.
-
Doug
Do you have enough head bolts that you may want to sell?
I checked the crankshaft bearings and there is several hard spots I dis not noticed before. I Guess new ones are mandatory. How do we remove them?
I may check that with bearing supplier...
-
Eric,
The head bolts that I made are for an earlier model (600EW) and so have a different (and much more ornate) head than what the Aero used. The Aero head bolt looks like this:
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/headbolt.JPG)
A tall hex head, domed, and the thick, plain washer. I don't know that these should be bright; I think originally they were cylinder black. My originals were rusty and quite pitted so I had remade them (many years ago now). I would have to dig the originals out of storage to see if the shanks had any trace of nickel plating on them, but I do not remember such.
The standard practice for getting the crankcase bearings out is to gently heat the surrounding aluminum with a propane torch until just to hot to hold and than thump the crankcase face down on a block of wood so that the inertia of the bearing causes it to drop out of the bore. If it it particularly stuck in place reaching through with a soft drift tapped against the inner race to get it started is o.k. Be sure to work your way around equally so as to not cock and jam the bearing in the bore. Note that hammering on the bearing so that the shock is transmitted through the balls is a definite no-no, but light tapping is probably o.k., and if you are going to replace the bearings anyway it doesn't matter.
-Doug
[fix typo. 31Jul19 -Doug]
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I have well the same screws at least on one 1 cylinder. And they are plated.
Allen screws on other cylinder.
I would like to have same screws on both sides even if not originals...
On a different matter, how do we handle unleaded gas?
-
What are the tanks capacities?
I will have the tanks treated with a resin and I need to get that information to order the right kit.
The reservoir is well made of steel (not aluminium)?
-
Eric,
3.5 gallons fuel and 3 pints oil.
The lack of leaded fuel is generally not a problem unless you run high mileages or run the engine hard for continuous periods such that exhaust valve seat overheats and starts to transfer metal to the valve (valve seat recession). Leaded fuel, introduced in the thirties, helped combat that.
The increasing use of ethanol in fuel is a more significant issue, and you may find you will have to alter the carburetor settings to compensate. There have been quite a few posts on that topic relating to the postwar models.
-Doug
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Doug
Thank you for the information. I am assuming that is Imperial gallons and pints even if it do not make a huge difference with US standards.
Any idea about the head bolts? Any spare to spare? Anybody knows where we can get them?
-
Eric,
The tank capacity came from their catalog information, so would indeed be Imperial units vs. US. When in Rome, as the Romans do...
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/1937-Aero-600.jpg)
I did not make any extra of the Aero head bolts at the time (it was 25 years ago), though these days when I do make something like that I often run off a few extras when I have the machine set up. I do not have any plans to run them again as I have too many other things to machine, but could provide a drawing if you can get them machined locally. Otherwise it would be a matter of advertising here or in the LDMCC magazine.
Unfortunately, and for no good reason I can see, the head bolts are different between the 500/600cc Aero and the 250/350cc Aero.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2018/1936Aero/aero-head-bolts.JPG)
Both 5/16 diameter, but one a fine thread and the other coarse. Also different lengths, height of dome, and even diameter of the washer. They could well have used the same bolt for all four engines, but did not. Which is a pity as quite a few of the 250/350cc engines have been scrapped looking for crankshafts and conrods that can be altered to keep the 350EW running, so someone might have saved some cylinder bolts and other hardware. However they will not do you any good for a 600.
As you can see, no trace of plating, so original finish would have been black stove enamel.
-Doug
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Well I found a company that could make the bolts but for just a set they said it would not be effective.
I posted a message in the parts of the forum but nobody interested at this time...
So I will stay with the current set up for now until I found a solution.
-
I removed the valves to paint the cylinder and heads.
I marked them to put them back on their respective port but is it required to rotate them to the same position? (I marked them to do so anyway)
Also do we have to clean them down to bare metal?
-
Hi Eric,
have you checked the valve seats / valve surfaces?
When you have the valves out, it is a good chance to "fresh up" the seats with regrinding.
Michael
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No I did not checked but I will have to show them to somebody with more knowledge and probably regrind...
-
I finally had a chance to pay a visit to the company I met at a show last month so they can rebuild the flywheel/crankshaft cone.
We may not go to welding as the flywheel can not be welded all the way in and it would be better to use an intermediate cone. He's thinking right now as to what he can do.
It looks like I will have to have the faces of the valve lifters resurfaced as they are slightly marked. I thought it was fine, he said no.
Also a rubber has been placed behind the bearing on the flywheel side. Is that original?
The bearing is marked SRO. This is a french company that went out of business during the war, so I think the bearing might be original. I will keep it as it's good enough.
The other one will be replaced as it was not quite nice although quite usable.
Sandwiched between the SRO bearing and the rubber I have a thin washer. The mechanic said it was useless and he "would not put it back" as he see no use to this.
Any comment will be appreciated.
Cheers
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181210_110153.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181210_110139.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2018/20181210_111453.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
As mentioned previously, there should be a oil slinger between each end of the crankshaft and the adjacent ball bearing. Not only does this limit the amount of oil blowing through the bearings, it stops any large debris that inadvertently might get loose inside the engine from getting into the bearing. If your mechanic does not recognize an oil slinger and the use thereof, find another mechanic! Between the flywheel side bearing and the crankcase will be any shims required to limit end float of the crankshaft assembly. Even back then 21mm wide double row ball bearings were going out of style, so a 20mm bearing and a 1mm shim was the normal starting point; and then the shims were added to set the end float. I cannot just now remember for certain if there is a felt seal on the drive side; I am reasonably sure it did have one. Often there was on many of the models in this era. If there is a 3/6 to 1/4" deep recess in the crankcase between the bearing and the crankcase wall, then it certainly had a felt. If so, then another oil slinger is required to act as a shield and keep the felt out of the bearing. They were not using rubber rings or seals.
Most late-twenties and thirties Douglas engines that I have taken apart where I felt the bearings might have been original were SKF or Norma-Hoffman brands.
I don't think the face of the tappet adjusters is particularly hard, so resurfacing them and accidentally cutting through the case hardening should not be an issue. The problem with the wear is that you don't know exactly where the valve stem is going to land after a new adjustment. So if it lands half on the original surface and half on a worn pocket, you only have half the full bearing surface. As the valve stem is likely harder than the tappet adjuster, it will rapidly wear into the face of the tappet adjuster until the contact patch approximates the full diameter of the valve stem. Which means the valve clearance will go out of adjustment quicker than it otherwise might have.
-Doug
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Well I will check with him about the oil slinger; I am surprised as he's definitively involved in motorbike engines and even though a young businessman, he built a lot of motorbike engines, working on hi-performance 2 strokes engines and working earlier for a motorbike restoration company.
The bearing in place now is well a 21mm.
It looks like a least one felt has been replaced with a rubber on this engine... I will check the other end.
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I still wiat for the repaired crankshaft to come back...
In the meantime I would like to attend a concern with the kick.
When I use it there is a feeling like if teeths were missed on a pinion.
I see return spring has been changed in 2005 and 2012 and in june of 2012, a hand written note says "Kick Start "POB" and in may of 2012 a Spur Gear Standard Bossed has been invoiced by HPC Gears Limited.
Not sure if those last 2 items are related?
What should I check first. Do I need to open the gear box?
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Eric,
You only need to take the outer cover off the gearbox to examine and work on the kick start mechanism; you do not need to disturb the rest of the gearbox.
Quite possible a tooth has broken.
Douglas always did have a little bit of a problem with kick start mechanisms. The 3- and 4-speeds of the thirties main flaw seems to be a prevalence to jam, particularly when the kick start gear teeth were just starting to engage. They tried to overcome this by using a modified extended addendum tooth form that resulted in the teeth looking rather pointed. Replacing with conventional pinion can cause a problem in miss-matched tooth forms. Same situation as running a 20 degree pressure angle gear with a 14.5 degree pressure angle. Or if both the pinion and quadrant have been replaced with matching standard gear tooth forms, the tops of the teeth can abut when the quadrant starts to engage, which stops the quadrant gear from going into mesh. Hence the pointy teeth; the quadrant is more likely to fall into the tooth space between. Also I think the first tooth on the quadrant may have been eased back and made more 'pointy' so it too would fall into mesh easier.
-Doug
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The crankshaft has been worked on and the cone rebuilt. However the machinist checked the other end of the shaft and found it was off by 0.2mm on the end.
Since the bike was running fine until now except for the un-locked crankshaft, is it an acceptable offset or should he make it run straight? (or straighter as he said he had not yet checked if it was S shaped or just bent...)
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Eric,
I know it is a long and limber shaft on the timing side and the bushing in the timing cover will force it true, but the total indicator reading ought to be less than that. A run out of 0.2mm is going to cause undue wear on the bushing. You want to aim for 0.08mm or better.
-Doug
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Eric
Do you still have your gearbox apart and if so could you take a photograph of the kick start return spring. I did post a request for help a few weeks back as the new spring I fitted to my Aero did not fully return the kick start lever. I have now established that the new spring I got from club spares is for a 3 speed box and not the 4 speed. Unfortunately they don't hold stcck of any other spring for the Aero and the problem is further complicated by the fact that the club does not have an orginal drawing of the 4 speed spring. Before I or the club get some made I would like to make sure that we know what the correct spring looks like. The broken one I removed from my gearbox again does not appear to be correct and probably why it failed. Photographs of the spring I got from club spares and the broken spring are attached to my original post. Any help will be greatly appreciated.
Roy
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Gear Box still closed but springs has been replaced at least twice by previous owners over the last couple of decades. But I will let you know and in any case I will post questions and pictures here.
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Hi Eric
Maybe your bike has also been fitted with the wrong return spring and this is why it has failed a couple of time. If you can provide a photo at sometime it would be very helpful and hopefully we may eventaully be able to get some correct springs made up. Thanks
Roy
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Sorry I hadn't yet opened the kick mechanism.
Got the flywheel back from the machine shop.
And of course, waiting for those parts I did not managed to give the tanks a good cleaning and resin treatment and still need to give a coat of paint on the magneto plate.
On this plate we have the oil tap. I removed the screw holding in in place and the mechanism/tap/glass aluminium body do not comes off. Is there any trick there? Any other bolts/screw/nut to remove?
I did not removed and do not plan to remove the oil pump itself.
Also I see on the oil tap a plastic disc numbered 0 to 3 with a needle on top of it that can be rotated like to have an adjustment mark.
I assume the disc must be rotating with 0 matching the ratchet when closed and then the driver can adjust to 1, 2 or 3 with the needle placed to the most common setting for his bike.
I don't remember having seen anything in the manual about that.
There is a bolt holding the tap on the body. Is it just a question of removing the nut to get the tap off? I assume the tap has a "plug" on the bottom of its shaft. Will it come off the body?
Is there any adjustment on this nut as it looks like if the nut interfere with the tap adjustment.
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Eric,
There are two screws holding the oil sight glass to the corbel on the timing cover. One is the external screw that you readily see. The second is in the bottom of the bowl, where the oil drains out. You have to remove the glass to access it, but if you clean it up a little, you should see two slots for a screwdriver to facilitate removal.
The numbers on top of the oil flow needle do not correlate to any unit of measure. They are just for reference so that you can return the adjustment to any previous value that you found satisfactory. You would set the pointer to the value that gave the optimal oiling rate for normal riding conditions.
-Doug
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I am preparing the cylinders and heads after having painted them with a special paint for bike's engine.
1. I should have made it before painting but how do you remove the black carbon residu that we have near the valves and in the head?
2. The surface on the head and cylinder gasket plan is not so nice. I don't plan to have them grinded but I would like to have a good cleaning. Is it a good idea to use a piece of glass (supposed to be flat and I have the old sand cabinet window that has been sanded !) and 800 grid abrasive compound?
3. About grinding the valves seats, I have Abrasive compound in 240 and 800. Which one can I use?
4. I know that I have to anneal the brass/copper head gaskets. What is the best way to do it?
5. I guess I have to clean the inside of the cylinders/barrels. Do we have to use this tool below?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/51GbBZGMxOL_SL1100_.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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Eric,
There are some carburetor cleaners that will soften carbon deposits but it is probably not worth the risk to the new paint. So typically one manually scrapes the carbon off with a copper or aluminum tool that will not cut into the iron.
A plate of flat glass and abrasive compound is the classic way to lap a surface flat. But it is slow and eventually will wear the glass to a non-flat condition. I use a sheet of wet/dry silicon carbide paper (sandpaper) tapped to a flat surface. This saves wear and tear on the flat surface, and one can start off with coarse grit and rapidly change to finer grit. Nowadays it is easier to find a range of different grit sandpaper in one's workshop supplies than a range of grit compounds. Some light oil or soapy water on the paper will stop it from clogging up too quickly.
Valve lapping. I tend to go with what I have on the shelf in the coarse, medium, and fine grits without looking at the numerical grit value. Some of the tins are so old the labels are not legible anyway!
To anneal copper you heat it to a dull red (in dim light) and either allow it to cool in air, or plunge in a bucket of water. I have seen temperatures quoted of anywhere from 400C to 700C. Quenching in water does have the advantage of cleaning the surface. A little acid in the water will help if the discoloration/scaling is tenacious.
The tool shown is typically what is used here to clean and lightly hone brake cylinder bores. I suppose larger versions can also be used to clean cylinder bores and remove cylinder wall glazing and put in a new cross-hatch pattern to help new piston rings to bed in. But I would not expect that type of hone to do much to resize or true up a bore, nor would I use it to remove a cylinder ridge (the ridge formed where the top piston ring stopped.)
-Doug
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Thank you Doug
As for the de-glazing of the cylinder's wall, if you don't use a tool, how would you do it?
I am not using any new part (rings or pistons) and I have not seen any cylinder ridge.
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Eric,
Usually for de-glazing you would use an inexpensive tool such as this:
(https://www.douglasmotorcycles.net/aa-files/images/doug/2019/de-glazing-tool.jpg)
But if you did not want to buy a tool at all, I suppose it could just as well be done with a flexible hand abrasive pad like 3M ScotchBrite or similar nylon matting embedded with silicon carbide grains. Then just get in there with your hand and a helical motion. The cutting action will be so slow that unless you are at it for hours I doubt that you will make any alteration to size or wear any local hollow spots into the cast iron.
-Doug
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I guess I can say that the re-assembly started, at last.
Lapped and installed the valves.
Any one can confirm the parts are assembled the right way on the valves?
Just noticed that the 2 springs on one cylinder are different than the 2 springs on the other cylinder.
It's barely noticeable on the pictures but the springs are smaller in diameter on 1 half (upper) of their lengths. Any comment?
It's how they were and I put them on the right cylinder. Although I am not sure of the inlet/exhaust position but I lapped them anyway...
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190603_173211.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190603_164538.jpg)
[Attachments converted to linked images. 07Dec21 -Doug, Admin]
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If it helps my springs are all like the one on the right in your pic. As regards the others with smaller diameter at one end personally I'd fit them with the smaller diameter at the top (collett end). Good luck with the rebuild.
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Well I have not worked too much on the Douglas recently. My lack of engine experience makes feels like I am facing a mountain and I am not sure I can make it to the top.
Anyway, I was having a look at the cover that bear the oil pump and dynamo considering painting it.
However I need to remove the oil drip tapet. There is a large nut in the system, under the glass. However the dripping tube is in the way. This tube moves a little bit but stays in place. Can I pull on it to take it off? Is it just slide in?
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I am not sure if the tube is easily removable, but I did manage to undo that slotted bolt without removing the tube.
If you remove the small bolt at the rear of the oil drip assembly then it is possible to turn the whole assembly anti-clockwise which loosens the slotted bolt & then it can be easily removed with a flat blade screwdriver.
Be careful that you do not lose the tiny spring & ball bearing that resides at the rear of the top assembly, as it will fall out when you turn the assembly.
My spring was broken into 2 pieces, so I wound a new one out of music wire (guitar string!).
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Eric,
I seem to recall the oil bib threads in, but I was able to work around it in-situ with a screw driver to undo the hollow screw in the well of the bowl.
-Doug
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On my 600 Aero and my son's 500 Aero the drip tubes are screwed in. I used a pair of thin nose pliers just to gently rotate the tube. Refitting the tube is a bit fiddly or my fingers are too big. I inserted the tube into a bit of thin rubber pipe and was then able to screw the tube back in place giving it a final tighten with the pliers.
Roy
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I finally went ahead and prepared the parts to put them together.
I am anxious as I never went so far in disassembling an engine and would like to avoid making mistakes in re-assembling.
Plan is
1- install the bearings
2- Close the 2 Halves on the crankshaft.
3- Install the pistons and cylinders
4- Install the timing side
5- install the oil pump cover and generator.
And what do you think of my pistons? I have 2 scratches on the side.
Sorry pictures are a bit large :roll:
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185740.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185745.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185811.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185838.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185846.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_191501.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_191507.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Hi Eric,
the marking on the pistons would suggest to me that there is insufficient piston to bore clearance.
I have had similar issues with my engine & had to hone the bores twice.
It seems these engine need a lot more clearance than most machine shops realise.
At the top of the piston just below where the rings sit you need around 6 to 7 thou clearance, and at the bottom of the skirt you need around 5 thou clearance, piston to cylinder, measured at right angles to the piston pin.
It would also be a good idea to have a trial assembly of the crankshaft, bearings & crankcases, to see if you need to shim between the crank & the bearings to get the crankshaft axial clearance down to a reasonable level.
Mine needed around a millimetre each side, although I have also installed a thin 0.15mm paper gasket between the crankcase halves.
Originally there would have been a 1mm thick oil thrower washer installed on each side of the crankshaft, which would account for the need for shims around the same thickness.
(https://www.douglasmotorcycles.net/aa-files/images/aero/2019/Douglas_aero_crank_fitting-002.JPG)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Eric,
I am personally not a fan of plastic cages for bearings used in engines. Particularly ones where you often have to heat the case up to drop the bearing in and out. Also, the one on the timing side looks to be very light duty, given the few number of bearing balls.
As mentioned already, you will need to assemble the crankshaft in the cases at least once to test the end float. There are ways to pre-measure this, but most folk do not have the measuring equipment and fixturing to do it. I forget now if the Aero 600 was still this way, but earlier engines were designed for a 21mm wide bearing that even then was becoming obsolete so they incorporated a 1mm shim with a 20mm wide bearing. Even if that was addressed, they still typically bored the flywheel side deep so as to allow for a few shims to get the end-float just right. The shims go between the flywheel side crankcase and the ball bearing.
The pistons look like they have been clawed by a bear! That is more than what would be described as a few scratches... Ease down the high spots and reuse with new rings. It is not ideal, but probably you do not have much choice as pistons are getting hard to come by. Is that recent or old history? If recent, then there is still a problem that will need to be addressed as to why the pistons seized.
-Doug
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Thank you Doug and Aero
You point out the weak design of the bearing. Maybe I shall use the old one that was not really bad.
As for the pistons, they have no history. I just removed them to work on the crankshaft and have the flywheel cone rebuilt. I just took them off and put them aside.
I didn't had any trouble with the engine as far as I can tell. Only problem was the clutch.
There is no matching seizing marks in the cylinders as far as I can see. Even though the cylinders are not nice. I will send pictures of them later.
Do you have links to get rings?
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Here are the pictures of the cylinders. 2 of the same cylinder as it came off the engine. One slightly honed.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185652.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185707.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190909_185711.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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They look like they need a bit more honing. As mentioned previously check the piston clearances to see how little or much you can hone. For the last 10 seconds of honing, with the drill on slow speed, move the hone rapidly up & down the length of the bore, this will give you a nice "cross-hatch" finish that will help the rings bed in quickly. There is a place near me (Shropshire) called FW Thornton who will supply piston rings worldwide.
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Thank you for your help.
I called the mechanic that made the cone and I will visit him on Monday so he can have a professional look and measures of cylinders and pistons. He will check for roundness or lack of the cylinders.
I will have him check this tiny bearing too and the rest of the engine.
In the meantime I would appreciate to get the factory dimensions of the pistons so I can check if I have originals or replacements as well as the bore dimensions.
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Anybody could tell me if those pistons are originals?
Anydimesions available?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190916_114026.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20190916_114048.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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They look like Hepolite replacements, the same as mine.
Standard bore is 74mm, with oversizes at 20, 40, & 60 thousandths of an inch, so roughly 74.5mm, 75mm, & 75.5mm.
If you clean the piston tops the oversize should be marked "20 thou" etc on the crowns, together with Hepolite or Heplex. They are unavailable new these days.
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Do we know if Hepolite replacements are the same dimensions everywhere as the originals. We may have to chase for replacements so need to know what we are looking after. If we found replacements that are different than the Hepolite but same as originals it would be too bad to miss them.
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Original (I assume) on the left, Hepolite on the right
(https://www.douglasmotorcycles.net/aa-files/images/aero/2019/Douglas_Aero_600_pistons-001.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Underside
(https://www.douglasmotorcycles.net/aa-files/images/aero/2019/Douglas_Aero_600_piston_underside.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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I talked to the engine builder this morning.
Cylinders are measured at 74,75mm. Pistons 74,60mm
Cylinders' walls are porous and he's advising re-boring.
However how can I get new pistons? What are the options? He advised against custom made pistons as quality is not really good on his experience...
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Eric,
If the bores are not marked, don't get them rebored - rebuild the engine with the old pistons, but fit new rings. With .15mm clearance, they should be fine! Ignore the comment about reboring because the bores are 'porous' - taking another .25mm cut wont make them any better - in fact, 'porous' bores will retain more oil and prevent further 'nipping up'. Also, don't get too paranoid about the quality of repro pistons - the originals wouldn't have been any better.
When you rebuild your engine, build it on any cheap motor oil until it is 'run in' - then go over to a better quality oil. Modern oils are so effective that the running in process doesn't get completed before any high spots become glazed. ( I used to work on marine diesels, and one of our craft had to have all the liners and pistons replaced under guarantee because too good an oil had been used during the running in period, and the bores had become glazed!)
Regards,
Eddie.
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Great thank you Eddie for bringing some good news.
I assume it still have to be honed though??
Just in case so I/we know, what would be the options should one need pistons?
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As Eddie has already said, 0.15mm is a good clearance so best to just lightly hone any marks out of your cylinders & re-use the old pistons.
I have a couple of good used pistons measuring 74.7mm if ever you get stuck in the future, but I'm holding on to them for the moment in case I find any spare barrels.
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I got the engine parts back.
They surfaced the heads, the top of the cylinders and honed the cylinders somewhat.
As said earlier, he was concerned about the surface quality of the cylinders being porous but I asked him just to hone the cylinders without re-boring them so he did the best he could.
They supplied new rings but did not cut them. He told me to adjust with a 0,4mm/.016" gap. Is that OK?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191021_112144.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191021_112151.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191021_112558.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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It looks like your engine builder has used long honing stones.
In this instance I think a flex (ball) hone would do a better job.
Somewhere between 12 & 16 thou is ok for the ring gap.
If you gap them now at 12 thou by the time they've bedded in they will probably be more like 16.
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Looking at reassembling the engine now and here is a first question.
The bearing on the crankshaft, clutch side is a tight fit and slides in tightly. Surface on the shaft is rough. Removing the burrs may make the bearing loose on the shaft.
How would you do it. Install it with some kind of compound, dry, file off the burrs?
Also I have an oil sling on the same side on top of the bearing. How can I measure and determine if I need any more spacers/washers. How close does it need to be?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191104_102843.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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No Idea?
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Eric,
The state of this engine continues to dismay!
I would stone off the burrs. It is a similar situation to the practice of center punch marking shafts. Besides being a deplorable practice, over time the high spots get compressed, resuming the original slack fit. Better to know now if the fit is slack and not providing the proper support and remediate it.
I do not know if this is worth the trouble for a single engine, but I made a simple gauge to measure the end float of the crankshaft for the DT engine since I have done a several and have a few more to do. This is a cylinder of aluminum turned to just a little under the ball bearing outer diameter so that it is a slack fit . Both ends are faced square with a chamfer equal to the bearing radius. The length is not critical other than it needs to be a little less than the distance between the bearing bores. To use, the measuring cylinder is inserted into where the bearings would go and the crankcase bolted up tight with any gaskets that you will be using. The measuring cylinder is push all the way to one side until it bottoms and a dial indicator is arranged to contact the end face and the indicator zeroed. The measuring cylinder is then pushed to the other side until it abuts and the indicator reading of the distance traveled observed. The distance inside the crankcase is the indicator reading plus the length of the cylinder. Then I assemble the bearings and slingers onto the crankshaft and take a measurement across the outside. I then can figure out how much shim is required to achieve the desired end float. That enables me to set the end float in one try. It requires several things not everyone may have available; a bar of metal, an lathe, and measuring equipment.
The traditional way is to assemble the crankshaft into the crankcase and using a mallet, thump the crankshaft to one side and measure the distance from some reference point on the crankshaft relative to a reference point on the crankcase. Then using the mallet to shift the crankshaft to the opposite side the measurement is repeated. That tells you the end float of the crankshaft. You then add or remove shims from behind the bearing races (usually on the flywheel side if both mains are ball bearings) to correct end float. The nuisance is the bearings are a shrink fit in the cases, so you have to go through several sessions of heating the crankcase to pop the bearing in and out as to experiment with shims.
-Doug
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Doug
thank you for this information
The thing is the shaft has no really burrs or high spots. It's just not smooth. Bearing slides in and out without feeling any rough surface. It just pops in and out. It's a bit tight and I have to play it around so it can slide in. Making the shaft smooth would have some play...
Not sure to understand though. The bearings are inserted in the case and then shims are between the bearings and the crankshaft. It was this way when I took it apart. But why do you say "you have to go through several sessions of heating the crankcase to pop the bearing in and out as to experiment with shims".
Seems to be the opposite than "behind the bearing races (usually on the flywheel side if both mains are ball bearings)"
Then wouldn't it be easier to fit the bearings first and using the aluminum rod sliding bar method measure the required length of crankshaft+shims?
Those are going to be tiny shims but do we want one on each side to center the crankshaft or is it not important?
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Eric,
The factory installed the shims between the crankcase and the bearing. There are slingers (in some designs) between the bearing and the crankshaft, but these are not intended to be shims. Presumably Kingswood (and other factories) did this to protect the thin and delicate shims. If they were installed on the crankshaft they would be more prone to damage during assembly. The crankshaft journal has a fillet between it and the throw to avoid a stress riser. If the shim registered on the crankshaft, the hole through would have to be bigger than the journal so that it would clear that fillet. During assembly you would have to be careful the shim rode up that fillet and registered on the flat face, else it might get pinched and not allow the bearing to seat fully. Also they might have figure the crankshaft shuffling back and forth the amount of the running clearance would unduly hammer or at minimum compress pinch the thin shims as the crankshaft flexes, so behind the bearing they are static as well as better protected. It seems to be normal practice, not just with Douglas.
I actually do not remember a slinger(s) on my 1936 Aero, but it has been a while since the engine was assembled and I did not take a photo of the assembled crankshaft that I can refer to. Most designs have a shallow spigot for the slinger to register on, just for the purpose to keep it off the journal radius. I do have a picture of the disassembled crank, and I do not see a spigiot for the rabbet so the must have done without.
Anyway, since the shim is behind the bearing, it has to be installed before the bearing is shrunk into the case. And since the traditional method involves some trial and error, the shim (and bearing) needs to be removed/installed several times until one gets the shim amount correct. I think that also answers why you cannot us the aluminum bar to just gauge the distance between the bearing races once in the crankcases.
One could divide the shims between the timing and flywheel side, but to be honest I cannot recall ever finding shims anywhere but on the flywheel side. The amount is so small, that it is neither enough to throw the rods significantly off center, or enough to correct any misalignment of the conrods. The rods rarely are exactly centered nor is it critical (allowing for the usual no rubbing, turns over freely, etc.) The flywheel side crankcase is easier to heat up to fix the bearing; easy access inside and out for the application of heat. I suppose that is why the shims are installed on that side.
-Doug
[fix typo. 14Nov19. Doug]
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I used 2 x 0.3mm shims to get my endfloat correct, in conjunction with 0.25mm thick paper gaskets between the crankcase halves.
Might be a good starting point?
PS that is in conjunction with the 2 oil slingers, which are each 1mm thick
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I got a bar of aluminum and will turn a tool next week.
so if I got it well we should have :
Shim - Bearing - oil slinger - crankshaft - oil slinger - bearing - shim (if needed)
I had something "different"
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Well the bar I got was too small in diameter so I had to use regular washers lathed down.
I screwed one on one side (not proud of the job there), drilled and thread the other end so I can use an adjusting screw.
Then another washer and a plate of aluminum (I might as well use on this plate) with a small hole to slide a scredriver and I have an adjustable gage that can be measured out of the engine.
Thank you Doug for the idea to use this kind of tool.
When I will have measured this length and that of the crankshaft, I will come back and see what I need in term of shims and oil slingers.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191118_162641.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191118_162528.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191118_162545.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191118_162535.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191118_162611.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Well the design of my tool may work with somebody with better lathe skills than me. But the play in the screw, the staking of washers makes it 0,3mm "bent" from one side to the other.
Now the question is how accurate do we need to be there? I assume we still need to have a bit of play between the crank and the engine?
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Sorry, anybody can help me on my question?
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I couldn't find any mention of crankshaft end float tolerances anywhere so set mine to 4 thou & the engine is running well.
I also fitted a modern nitrile oil seal to the flywheel side crankcase whilst the engine was apart, as there is enough lube for the primary chain & clutch from the breather alone on these engines
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Heres a pic of the seal mod
(https://www.douglasmotorcycles.net/aa-files/images/doug/2021/heavyweight-aeros/VW_LT_rear_door_hood-001.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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The engine has the same modification...
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So nobody have any advice except Aero on crankshaft end float tolerances? .004" seems tight for me.
Then where will I found the shims? Can we buy them off the shelves?
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Don't forget you are in effect levering against the end of the crankshaft every time you pull your clutch in.
Too much end float & you will actually see the flywheel move out when the clutch is applied.
Trust me, it is not the first time I have done this ;)
Shims are easily available on ebay.
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I managed to make some measures as best as I could. Some parts are not easy to measure s I did my best.
Adding the bearings and the crankshaft, I come to 121.94mm - 122.34mm
The engine blocks as from face to face 124.14-124.44mm
That leaves 1.80 to 1.2mm for the oil slings and shims. I have oil sling (OK did not measured it and it is not smooth, so may replace it?) (That's .071" to .098")
Do I need oil slings on each side? I had one only on the flywheel side.
If I can get oil slings of such a thickness that I don't need shims, am I OK?
Sorry but I have not been able to find shims on Ebay (not familiar at all with this site) and our local machinists have nothing.
Saw a laser cutting company but they have only 1mm 1.2mm and 1.5mm steel. Maybe 2x1mm would fit.
do I need stainless steel or regular steel for shims and oil slings?
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Are you going to use thin gaskets between the crankcases, as you will need to allow for those too? I used 0.25mm paper.
Heres a link for shims, but there are plenty of others if you search when you know the exact size
https://www.ebay.co.uk/itm/0-5mm-THICK-SHIM-WASHERS-HIGH-QUALITY-STEEL-DIN-988-ALL-SIZES/253287469547?hash=item3af91c11eb:m:mL7tYo9RonYTvbphx9unn2w
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Yes paper was installed when I measured.
Thank for the link. When they say M42x52mm, does it means 42mm ID and 52mm OD?
I just need to hear from Doug or Eddie for the play I need to leave. Or I'll go with .004" like you did. However based on the lack of accuracy of m measures, I need to know how tight I need to be. I would have then to have it measured accurately somewhere should I need to be "close" or tight.
Is it better to have 1 shim behind each bearing or is it just not important? I mean better to use 2x0,2mm or 1x0,4mm?
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Thats correct, M42 would be the ID in mm, and 52mm the OD
Personally I fitted the shims between the crank & the oil slingers. This meant I didn't have to remove the bearings to alter clearances.
Maybe not perfect engineering but it works.
Using this method its easy to assemble with no shims, check the end float & then add/subtract shims.
I did have to profile the inside of the shims to clear the radius on the crank however & I would suggest using a single shim and not "stacking" them if using this method.
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Then did the oil slinger act as a shim?
Do you use oil slingers on both sides?
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The oil slingers were 1mm thick & the diameter was just big enough to obscure the ball bearings.
I used one 1mm slinger & one 0.3mm shim on each side of the crank.
This gave me 4 thou clearance. I was aiming for between 4 thou & 8 thou.
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Right now I have 2x1mm 30x52mm oil slingers on the flywheel side.
Bearing "opening" is 52mm so the slinger barely covers the opening. Picture 1
On the link you gave earlier they offer 30x42. So OD is a bit small. Will it work?
The ones from the engine have a rough surface and there is 2. Picture 2
Can I still use them as they are larger or is it better to use a single piece, smooth although smaller?
On the timing side, the bearing is thicker than the shaft it rides so adding an oil slinger would take it off the shaft even more. Picture 3
Is it acceptable?
I can get a 25x35 slinger, with a bearing opening of 47mm !? Is it better than none?
Now inside the timing case, I had a real bad shaped shim/Washer/piece of garbage bent(!) to be roughly 3mm thick. Picture 4
Do I need it? Shaft here is 19mm and I could get a 20x28
How large and how thick I want it??
Now If we can use oil slinger of different thickness, why would one bother with inserting shims behind the bearing(s)? Isn't it more simple to ajust via the slingers?
Which brings me back to the same question, what are the required tolerances as thick shims/washers comes in 0,5mm increments?
Or shoudl I source other more size suited shims and slingers?
(https://www.douglasmotorcycles.net/aa-files/images/doug/2021/heavyweight-aeros/20191205_185140.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2021/heavyweight-aeros/20191205_185125.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2021/heavyweight-aeros/20191205_185028.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2021/heavyweight-aeros/20191205_185215.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Eric,
The oil slingers are factored into the design so an not included as part of the shims per se; same as factoring for the width of the bearings. If manufacturing and tolerance were precise enough there would be no need for shims. The factory would just machine to the required dimensions and on assembly it would have the requisite end float. But Kingswood's overall machining accuracy plus the variables of all the individual tolerances on the components of the crankshaft add up to quite a stack of tolerances which result in too much variation. So they make the bearing pocket too deep, and bring the end float back to the desired limit with shims.
They did not offer various width slingers to serve as a means to adjust end float. Presumably the traditional method of using standard, commercially available shims and popping the bearing in and out posed no difficulty for them. They were use to doing it every workday. They might even had some sort of fixturing or tooling that allowed them to pre-measure and set the shimming so they only had to install the bearing once.
But it is a thought. You might find it easier to make a custom slinger of the desired thickness rather than dealing with the aggravation of removing and installing the ball bearing from the case. I think this would be preferred to using shims between the slinger and the bearing. As already stated, one thick shim is better than multiples of thinner shims. Also, it can be arranged more reliably with the slinger not to get pinched on the radius of the main journal. (While I was typing this, I see you replied with much the same idea.) You could put the shim between the slinger and the bearing (inner race), but this is bad practice from two points. One, the inner race can rotate or creep on the journal, and you want the shim between two static members. Second, it increases the gap between the slinger and the bearing and one of the purposes of the slinger is to keep any larger, stray metal crumbs from getting into the bearing and causing catastrophic failure. Of course the smaller metal particles have probably already trashed the balls and races, but I believe that was the theory!
I have never seen a published figure for the end float on Douglas engines. You were expected to return to the factory or at least the local Douglas Dealer for that sort of repair. So you have to rely on general values from other engines or publications. That timeless source of information "Tuning for Speed" suggests 0.005" for speed work where the crankshaft does not require positive location (such as for the mesh of bevel gears to drive an ohc.) A maximum given as 0.010". Personally I would aim for about 0.004" as already suggested, just to make sure there is some clearance. While the crankshaft does run hotter, the aluminum crankcase will expand more so the clearance will only increase when the engine warm up. In theory you could aim for zero, as the clearance will increase with temperature, but I would not do so. I suspect the crankshafts whip a bit and that might just side load the bearings even more than usual if there was not some clearance to begin with. It also heats up first before the crankcase. I think 0.010" is just a little too much for a road going engine of the period (unless it is a Scott) so would not settle for anything over 0.008". With reliable measuring, I can usually get it within two thou of what I was aiming for (0.004-0.006") without going bonkers over it.
-Doug
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Thank you Doug,
Aero I don't want you to think I don't believe what you said, you've been quite helpfull so far. I just need to get as much information as I can and understand what I am doing which is quite challenging.
Aero what is the process to "profile the inside of the shims to clear the radius on the crank". Is it a larger ID or a radius on the edge? Do I need a tight fit of slingers/shims on the shaft and then a radius on the edge?
Doug don't we have the slinger rotate and creep on the journal too?
I asked for a quote on laser cut slingers, hopefully it is affordable...
If I input 2 - 1mm slingers in my figures, I come to -0.008"/+0.008" clearance so I definitively have to have the parts measured more accurately.
That leaves the question of this washer on the timing side. Do I need it, how large, how thick?
Aero do you have one on your engine?
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Received the quote @ 15€ piece without taxes !! I was hoping a bit less.
Anybody might be interested as I think that a multiple order may decrease the price?
Any other option??
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Hi Eric, I am by no means an expert on these engines but I've built plenty of others over the years. I too need to ask for advice when its a Douglas peculiarity and as no factory assembly info is available for our engines we really need to share as much knowledge as possible between us.
I had to take a Dremel fitted with a grinding wheel to my shims, and chamfer the inner diameter so it would sit flat against the crank. The oil slingers were already chamfered.
My engine is slightly different to yours on the timing side but there is no washer/slinger fitted to mine in the place you mentioned. There is however a spring retaining washer on the other (outer) side of the timing gear.
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pic
(https://www.douglasmotorcycles.net/aa-files/images/aero/2019/Douglas_Aero_generator_gear_cone_spring-003.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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pic
(https://www.douglasmotorcycles.net/aa-files/images/aero/2019/Douglas_Aero_timing_side_assembly_order.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Thank you Aero
I will check the timing side when I will be reassembling it.
As for the shims, I think I will use a 1mm oil slinger and a 1,5mm on the other side. I will slide in the bearings with no shims and then I can determine easily how much I need and have the 2nd oil slinger surface grind
I will go to a machine shop to have my parts measured (and my calipers checked as one (Chinese) is consistently "less generous" than the other one (Mitutoyo)
I will ask them the cost to have the slinger machine grind so I can see if its reachable.
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I will have the oil slingers cut in chrome steel rather than stainless. Seems mor eappropriate and I save 5€ per piece.
I finally made some good and consistent measurements. Or at least better than previously.
Will have the slingers cut in 1.2 and 1.5mm which should be fine as it will bring me to -0.001"-+.009". I may be able to adjust a bit by sanding one of the slingers.
As for the slingers, I will have them cut right to the journal diameters for ID and adjust for a smooth fit.
As for OD, I will have them covering half of the external race unless somebody advise otherwise...
Will wait for a couple of days before I order the laser cut just in case somebody want to add something.
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Eric, it is also possible to alter the crank end play a little by using different thickness of gasket paper between the crankcases.
When I first assembled my engine I had no oil slingers, so just used shims on their own, however when I had to strip my engine down again some months ago due to a crankcase stud pulling out I managed to get hold of some original oil slingers & used them in conjunction with shims. Unfortunately I only measured the thickness, and not the outer diameter. All I can say is from memory they just covered the external race enough to obscure the ball race. Sorry I can't be of more help but I didn't take many pics last time.
I'm sure chrome steel is quite adequate for their purpose.
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I feel that as long as the oil slingers cover most of the balls and do not extend beyond the bearing OD I think it would be large enough...
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Just thought that if the balls on the bearing are fully covered with the oil slinger this will prevent debris from entering the bearing but oil too ! No??
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Eric, there is nearly a quarter of a litre of oil sloshing around constantly so there should be no issue with it getting to those bearings with even the smallest of gaps however I think it might be best to make the slingers 1 or 2mm smaller diameter than the inside of the outer race, so you have a 0.5 to 1mm gap to allow the oil to circulate.
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I confirmed the order for
Timing side
1.2mm
25.0mm ID
45.0mm OD (leaving a 1.5mm gap on diameter (0.75mm on radius) of ball race opened)
Flywheel side
1.5mm
30.0mm ID
50.0mm OD (leaving a 2.7mm gap on diameter (1.35mm on radius) of ball race opened)
Any comment still welcome though
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I got the oil slingers. Well they made 1 in 1mm instead of 1,2mm. Should be fine though. Will check.
I deburred them today and worked on the edges so they are smooth and rounded (pictures shot before this)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191217_190634.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Plan is to install the bearings back in the engine block tomorrow.
A few questions of course :
1. On timing side, bearing is going past the journal. Is that a problem? I have no other choice except saving 1mm by not using the oil slingers on the other side.
2. How can I tell that the gasket on the block (flywheel side) is still good? It is smooth and not brittle. Crankshaft journal slide in with no effort.
3. Journal on flywheel side is not nice. Bearings (both) are sliding in and out of the journals easily but with no play. I can't improve the surface of the journal without increasing the play. My plan is to leave it this way.
4. Had a look at the head gaskets. Their fit is not 100% and they do not contour exactly the cylinders. Would you use them as is? I know I have to anneal them.
All and every comment is welcome.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191229_164301.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191229_164206.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191229_164221.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191229_163625.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Hi Eric,
1, the bearing is 12mm wide & the shafts shoulder is only 10.7mm so there is always some degree of overhang. Its not a problem.
2, just check there is a still a sharp edge on the seal where it touches the journal, ie its not worn flat. Also check the inner tension spring is still present.
3, leave it that way.
4, club spares should have new head gaskets. They are worth buying as your old ones look well past their best.
Hope you have a good new year & get your Douglas on the road soon.
Regards,
Mark
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Eric,
Additional two cents worth:
1. Sounds like it was designed for a 10mm wide bearing. How deep is the bore in the case? While you can get away with some overhang, they would not have designed it that way, indicating something is amiss.
2. Originally it was a felt washer for a seal. As Mark said, you can visually inspect the condition of the seal lip. Molded lip seals like that are really intended to run against hard surfaces, the crankshaft is heat treated, but not that hard on the journals. Eventually a lip seal like that will wear a groove int he journal and sealing performance will diminish.
3. There is a reason that the manufacturer goes to some trouble to active a very accurate fit for ball bearing journals and housings. A slip fit does not provide full support to the bearing race and might encourage it to creep around and wear more. You cannot Loctite the bearing to the journal, as one usually puts the bearings in the crankcase first. Well you could assemble it with a basting of Loctite, but i would not want to be the next person that had to get it apart! The accepted engineering fix is to have the journals built up with nickel electroplate and then resized. Can you just use it as is? Yes. Is it good practice? No. Even though it feels as if it has no play, the fact that it slides on freely means it DOES have play.
4. The head gaskets look like they have been cut from sheet copper. The original style would be copper faced asbestos (or substitute) sandwich. Annealed, solid copper gaskets can be made to work if both surfaces are flat or can be pulled up flat. Those look like an amateur effort. The lack of fidelity to combustion chamber is not fatal. It will leave a gap for un-burnt mixture that will eventual collect carbon. However we are not talking about a high efficiency engine or emissions compliance. But the slotting of the holes to meet up with the cylinder head bolts just offends the eyes!
-Doug
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Thanks for comment.
1. The bearing fills the bore in the case fully and is flush.
2. Seals is good to the eye so it stayed on post.
3. The bearings slides in not really freely (it does not slides in by its own weight). In any case I will leave the surface as is for now(?).
4. I applied for a registration to the club (at last) and I will get better gaskets. You're right Doug, it's offending.
Even though this engine is not perfect (crankshaft journal surface in mind), I want to make it as decently as possible right...
Bearings are in now.
Going to check crankshaft side play...
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Aero
I did not had any inner tension spring in this gasket. It was just black "rubber" all around!?!?
I see the same thing on your picture (Reply #279)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2019/20191230_091901.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Hi Eric,
if you twist the inner seal over with your fingers you should see a very thin coil spring that runs around the outside of the lip. Its to hold the seal in contact with the shaft
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Too late !
Did not tried to twist it over, just checked for hardness but have not seen a spring...
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Well I worked too fast (!!!) and put back the bearing before I know that I had to check for this tiny spring.
For peace of mind I removed the bearing. The spring is well there. Quite hidden and small but there.
But now, of course, the bearing that I checked and estimated as OK seems to have now hard spots. Probably removing it did not helped.
So before I can get any information back from the club with my registration request, can I get the information here whether or not the following parts are available and their part numbers
1 Head Gaskets
2 Clutch side bearing
3 Timing side bearing (I might as well replace it too while I am at it...)
4 Head bolts
5 Gear Box Kick spring
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Am I well reading 6Q/237?
Is that inline with what one shall expect there?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200104_160606.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Eric,
6Q/ is the prefix code used for the 1938 frame and engine. It was not known what was used for the transmission code at the time the model identification list was put together:
https://www.douglasmotorcycles.net/aa-files/html/identify-part2/vintage4.8.htm (https://www.douglasmotorcycles.net/aa-files/html/identify-part2/vintage4.8.htm)
but it would appear they used 6Q for transmissions as well.
A 1936 transmission would be either be M/***, P/***, or T/***.
A 1937 transmission would be U/***.
Other than the date of manufacture, I don't know that there was any difference between the 1936-38 500/600cc transmission.
-Doug
[clarify text. 08Dec21 -Doug]
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Thank you Doug
As I am not sure if I can get the bearing from the club, I called our local company specialised in old bearings and solutions for old engines.
I told him about your reply (post #252) and your concern about the bearing I got from them some months ago with a plastic cage and the light duty bearing.
He said that he was confident that his bearing was up to the job, that it was matching the bearing I pulled off the engine (same norm), the "plastic" was good up to 200°C and that its duty rate was quite good for the application.
Overall I should be better using this new bearing rather than the old (used) one.
As for the big one (flywheel side), they would have to use a 62-30x20mm and grind it down to 60-30x20mm at a cost of about 160€/135Ł/180$ !
So I hope I can get one from the club...
Talking bearings, he told me that they are supposed to be installed by "force" on the shaft and slide "freely" on the block. It's the opposite on my engine and the note Doug said (that it's a shrink fit).
As a reminder, the bearing on the timing side was a shrink fit, slide in by finger pressure in the block heated at 60°C whereas the big one, flywheel/clutch side, required some hammering in. And taking it out required quite some
He also said that once removed a bearing is not supposed to be used again except if "forced" on a shaft and can be heated to be removed without damage.
I plan to install them as they were (shrink fit on he block and free on the shaft) and I do not plan to have the journals built up !?
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Hi Eric,
the timing side bearing is also used on Vespa scooters, so easily available. Old SKF number is 6105, but the generic modern number is 98305.
The flywheel side bearing is slightly harder to find, but still available in the correct size of 30mm ID, 62mm OD, 20mm wide. There really is no need to get a larger one ground down. If you get stuck let me know & I'll see if I can find one in the UK for you.
I bought new copper head gaskets from the club when I rebuilt my engine so they should still be available.
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Thank you for the information I will double check for the small one
On the large one, it is 60mm, not 62mm, hence my problem.
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Eric, thats most odd. My flywheel side bearing is definitely 62mm OD & I was under the impression all years used the same one. Are you 100% sure yours is 60mm?
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Yes, almost all models had 62mm O.D. main bearings on the drive side from 1930 through to the last Dragonflies. Some late 20's/ early 30's machines had the wider (21mm) bearings that are no longer available (hence the need for a 1mm shim). When we were involved with the LDMCC spares scheme, we always specified bearings with a metal cage, but often had to wait for a new batch to be manufactured (typically, one batch every 6 months).
Regards,
Eddie.
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Sometime I wish I could fire the apprentice, but I AM the apprentice !
YES it is 62mm !!
I should be better paying somebody to work for me sometime, no, most of the time...
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The cover on the tool box on my bike is correct but has been repaired.
Was it stamped steel or aluminium cast originally?
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Cast aluminium.
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Doug
just to make sure we are talking about the same cover, here is the one currently on the bike.
Does it make sense to have a copy made out of it or should I rather find an original?
Mine is made of fiberglass on most if not all of its surface. I am not sure it's correct all the way through.
The founder will make a "model" and can cast more is needed.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/81990975_463099307663651_4565535456665534464_n.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/82362293_530199611038569_5500020314781777920_n.jpg)
[Attachments converted to linked images. 08Dec21 -Doug, Admin]
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Eric,
Yup, that is the one. These toolboxes are getting rather difficult to find, which is why someone probably made the replacement lid from GRP. The original is cast very thin; the main panel is only about 3/32 of an inch thick. Douglas must have poured the aluminum at its boiling point!
(https://www.douglasmotorcycles.net/aa-files/images/doug/2020/toolbox-lid/toolbox-lid-1.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2020/toolbox-lid/toolbox-lid-2.JPG)
(https://www.douglasmotorcycles.net/aa-files/images/doug/2020/toolbox-lid/toolbox-lid-3.JPG)
-Doug
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Is there anybody in UK that have a good condition original cover that may be sent for a non destructive copying?
My guy can have it molded in aluminum (maybe improved) in any quantity afte rhe had a sample and can make a pattern out of it.
He can cast any part by the way.
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About 20 years ago I needed one for my S6, so formed it from 3mm aluminium sheet. It easily shapes up from a single piece, with just a little bit of welding on the corner by the screw. The bottom lip that hooks inside the main box was made as a separate piece, rivetted on and the heads of the rivets flushed off.
Regards,
Eddie.
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I joined the club and asked for parts I need but the gentleman in charge of pre-war spares is ill and currently unavailable.
So I wopuld appreciate if can I get the information here whether or not the following parts are available and their part numbers, so if they are not available from the club I might work on other options :
All for a 1937 Aero
1 Head Gaskets
2 Clutch side bearing
3 Timing side bearing (I might as well replace it too while I am at it...)
4 Head bolts
5 Gear Box Kick spring
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Eric,
Back in 2009 I sent the LDMCC drawings for the eight models I happened to have head gasket information for, including the 600 Aero. They were contemplating at the time having having head gaskets made for some models, but I do not know it it ever came to pass.
Flywheel and timing side ball bearings. This was always seen as something the owner sourced directly from a bearing stockist, so the Club never carried them. It just tied up capital.
Head bolts. I do not recall the club ever making head bolt for any models.
Kick start return spring. The club has in the past gotten the 3- and 4-speed box return springs made. Looks like a clock balance wheel escapement spring. The two types look similar, but they are slightly different. Just make sure you specify which you want!
-Doug
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Thank you Doug
As for the head gasket, Aero said he got them form the club last year I guess
The bearings I will get them locally, that's the reason I was asking so I can move on.
The head bolts, I was in touch with somebody from the forum that planned to have some made but never happened I guess. That's not really urgent for me as I got them (4 originals and 4 Allen head) and I can replace them anytime later.
The kick start, I read on the forum the problem about the 3-4 legs speeds box. I am pretty sure I have the wrong one in at the time. I still have to open the gear box though...
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Hi Eric,
as far as i know the head gaskets are still available from the club. I think they may also have kickstart springs but as far as any other spares go for the Aero model you will be very lucky if they stock them.
There is someone on ebay selling springs at the moment here;
https://www.ebay.co.uk/itm/new-vintage-veteran-motorcycle-douglas-aero-600-kickstart-spring/174053711657?hash=item288668df29:g:-QoAAOSwTwddl8Ij
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Thank you for the information about the spring.
I looked and found the thread : https://www.douglasmotorcycles.net/index.php?topic=7349.msg28341#msg28341
It's not a matter of 3-4 legs as I wrote on the previous message but 3-4 speeds as Doug said (I corrected my message)
Doug said rightly that in the past the club had springs made, well this past was just 2019 (from above post) so hopefully I still can get this spring from the club.
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I am back !
I finally tested the 1mm oil slinger cut by mistake (I ordered 1,2mm) and it was not thick enough. So I had them recut anoher one in a 2mm plate.
I tested it and I had like 0,1mm/.004" play but when I assembled the engine probably I tightened more the engine halves and now I have almost 0 play. Is it enough or should I use a thicker paper gasket.
Now some questions about the below pictures :
1. Any idea where the 2 washers may go. They do not seems to come from inside the engine. They were just laying around on my bench...
2. I still have this awfull washer. Can't see it's use. Was there. Should I have a new washer cut and if so what size or do I need nothing under the first wheel (the one that links the 2 cam wheels). I know Aero already said he has nothing on his engine but just want to double or triple check that. And I have to re-read the entire 7 pages of this thread as I asked and may have replies already on this matter (and my memory sucks big time)
3. Re the bushings and shafts for the valve wheels, 1 is frozen in the bushing and the bushing do not slide easily in the hole (whereas the other one slides quite easily). Should I force the bushing and then the shaft in place or is it better to improve the fittings? Both can be force din place without too much force.
4. On the oil pump wheel and under the nut I don't have any washer. Is that correct?
5. The marks I made on the wheels are barely readable now. How can I time and check timing on the 3 wheels?
6. I noted the pistons to ID the front and rear ones and their sides but in as much as I had the cylinders honed and the rings replaced is it mandatory to use them on the same place or not? Just so I know as I will put them on their respective place anyway.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200224_183658.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200224_183230.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200224_182927.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200224_182414.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200224_182932.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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Any help there?
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I was looking at the Idiots Guide post from Kevin and Eddie talks about ignition timing.
Beside the valve timing I am looking for help above, I am now wondering how the ignition timing was made. When I disassembled the engine, I don't remember having made notes about the dynamo. I will have a look over the week-end but would appreciate to get an explanation on that.
And of course on my previous questions...
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Do we have any advice NOT to use 1mm thick paper gasket between both engine blocks? Is that too thick?
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Yes, 1mm thick paper is too thick - it is likely to cause distortion of the crankcase halves. If you need to space the crankcases apart by that much, make a spacer out of .75mm thick aluminium and then use a thin paper gasket either side of it. Be careful though, spacing out the crankcase halves will alter the pitch of the barrel studs as well.
Regards,
Eddie.
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Thank you Eddie
Using 0,5mm paper I have no play, using 2 layers of papers, I have .009"/.023" play on the crankshaft which seems to be the compress size of .5mm paper so I come to -.001"/+.001" crankshaft play with a single layer. I may try to sand paper on of the 2 oil slingers I had made (1 is 1mm the other one is 1,2mm)
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I made one of the 2 oil slingers about .004" thinner and I have a .003" play now.
Ready to re-assemble, putting things together...
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Sounds good.
Looking forward to hearing that it is up & running again
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What ring goes in the groove that has some ports? Is it the ported ring? I would have thought that ones goes on the bottom groove...
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200323_180427.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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Your pic is correct. The ring with the slots fits in the piston groove with the oil return holes.
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A friend with some good knowledge is astonished that we user a plain ring on the bottom groove where we normally found a pistol oil ring.
Anybody could explain this set up and why it differs what we susually encounter?
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Think of the bottom ring as a pre- oil scraper. More modern oil control rings are a lot more efficient and can get by with just a single oil ring. If the bottom ring were too efficient, you would deprive the skirt of lubrication.
-Doug
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Doug
my friend agrees with you that using a regular plain ring on the bottom groove would prevent correct lubrification.
What about preventing piston tilting? No ring on bottom groove will make the piston tilt, won't it?
In any case my friend advise one of the following set up. Of course the hollowed rings being larger than plain ones, they do not fit the bottom groove. I just discovered it and my friend is not aware so the set up with 2 scrappers (and 4 rings total) is impossible.
That leaves the previous set up of plain-plain-scrapper and plain on bottom.
I am assuming I am using new, modern efficient rings
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200326_120131.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200326_120210.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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Eric, I have the original piston ring set-up on my bike, and it doesn't smoke or use oil, so can't see any reason to differ from standard.
All I would suggest is that the pistons need a lot of clearance as I mentioned to you earlier in this thread.
I ended up taking the barrels off twice to hone for more clearance as it initially kept nipping up when hot.
I was using a caster based oil back then but the the engine didn't seem to want to "bed in" using that so on the last hone I washed it all out & used a straight 40 grade mineral oil & its doing nicely on that
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You're so right.
I remember you gave .006-.007 and .005 on the skirt as clearance value and remember the values measured in the cylinders and pistons were matching.
What is nipping and how do you feel it?
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Glad you have plenty of clearance, these engines need it.
Nipping is when you can feel the engine tighten slightly, and if you are quick enough you can pull the clutch in & coast to a halt with no damage.
Usually when the engine has cooled you can carry on but when this happens frequently you need to look into why its happening.
I had one occasion when I was following someone & in my haste didn't heed the warning quick enough & the engine locked. It did free up after a few minutes but after that I thought it needed looking into.
On stripping the engine I could see where the problem was as there were signs of seizure on the lower parts of the barrels near where they enter the crankcases, so I honed them out a bit more.
After taking it easy for a couple of hundred miles the engine has been fine since.
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my friend agrees with you that using a regular plain ring on the bottom groove would prevent correct lubrification.
No. Using a slotted ring in the bottom groove would prevent correct lubrication. A plain ring takes off any heavy accumulation of oil thrown onto the cylinder wall, but will leave some behind for proper skirt lubrication. It just wells up at the base of the skirt, they usually do not bother to provide any grooves or drillings to collect and direct it away.
The ring(s) does not center the piston. In order to prevent seizure during expansion, the ring groove has to be significantly deeper than the radial depth of the ring. This radial gap is significantly more than skirt clearance, so the ring does not contribute to centering. The piston never touches the rings except by the face surfaces.
-Doug
[fix grammar. 26Mar20 -Doug]
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Doug
Thank you for those explanation.
So I understand that the standard configuration (plain-plain-hollowed and plain on skirt) is required.
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Cleaned the pistons today
And of course some questions.
I can now read the markings on the piston. They are different make but both are +.030". I measured them with a small caliper the best I could and I have a .002" difference
Now one of the pistons is corroded on the top and top side. On the bottom of the top ring groove, it has some scratches, I made a picture of the larger one.
I also cleaned the ring grooves. Are they clean enough?
Cylinders are also about .002" different.
I will match the larger piston with the larger cylinder.
I cut the rings. I did my best but they are not equals. I have gaps of 12-13-13-15-16-16-17 and 23! (of course 2 are scrappers) Measured in the smaller cylinder. Gaps are +/-.002 larger on the other cylinder.
Question is does it makes any sense to use the smaller gap on the top, is .012 not too small? I can make it .014-.015 on the other cylinder.
Or is it just fine and I can use whatever gap on whatever ring?
Old ones were .020-.030
I marked the pistons for front and rear and top to put them back on same cylinder and same orientation. Of course the markings are now long gone. Since the cylinders have been honed, is that ok to use any piston in any orientation, even though the smaller will go in the smaller cylinder but I am not sure it was the case before...
So
1. Are the ring grooves clean enough?
2. piston condition remain still usable? I hope so as I don't plan to change them and in any case the engine was running fine with them in.
3. Any order/matching in ring gap dimension or we just don't care?
4. I cleaned and removed any gasket compound (used on top of paper) surplus and removed everything I can see. Is it quite critical given the oiling system to have a real clean engine interior or is it tolerant. I mean do I need to make 200% sure nothing is left behind that may plug the oiling system. Not sure of the pression and size of ports in this system.
5. any comment?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200404_152713.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200404_152720.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200404_152736.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200404_152759.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200404_152816.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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1. Are the ring grooves clean enough?
2. piston condition remain still usable? I hope so as I don't plan to change them and in any case the engine was running fine with them in.
3. Any order/matching in ring gap dimension or we just don't care?
4. I cleaned and removed any gasket compound (used on top of paper) surplus and removed everything I can see. Is it quite critical given the oiling system to have a real clean engine interior or is it tolerant. I mean do I need to make 200% sure nothing is left behind that may plug the oiling system. Not sure of the pression and size of ports in this system.
5. any comment?
Hi Eric,
1. Probably
2. They look OK, but the critical issue is the fit of each piston to its cylinder. Check there is more than 6 and less than 10 thou between the skirt of the piston and the cylinder wall at the bottom of the stroke. I assume the bores are ok - not too badly worn at the top. If there are any scuff marks on the pistons, smooth them off with a "flat" file - preferably a brand new one that has never been used on steel.
3. Personally, I think 4 rings per piston is way too many in a bike like this. I'd use plain rings in the top two grooves and leave the others empty. Not everyone will agree, so if you want to fit more use the order proposed above. Use the smaller gaps on the top rings, and the shockers on the skirt. The ring gaps should be set by filing, rather than cutting. Make sure - with a file - the ends of the rings are square and free from burrs.
4. Clean is good. If you have sand/glass/abrasive blasted anything internal you will need to clean, clean and clean again. A few tiny floaties of gasket material won't hurt, but if you wash thoroughly most should be gone.
5. Comment: If you don't have a copy of Radco's "Vintage Motorcyclist's Workshop" get one. It has most of the answers to our questions, and contains almost nothing that is "wrong". I like the way Radco recognises that we're not trying to build MotoGP racers, and cuts some slack to the home mechanic!
Cheers
Leon
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I didn’t want to start a new topic as the subject is briefly mentioned within the pages of this exchange. I have an Aero 6oo and my son has an Aero 500 but on both engines the ball and spring in the oil sight drip feed on the timing cover is missing. Doesn’t affect the running of the engines but as soon as we switch off, we have to remember to turn off the oil supply as the window will quickly fill up with oil. Both engines have a tap in the oil supply line. I believe the ball bearing is a Ľ inch, but can anyone give any dimensions for the spring – length, number of coils and wire diameter. I assume it is a very light spring, possibly something like a magneto brush pick up spring. Any help/guidance will be very much appreciated. Thanks.
Roy
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Interesting, I never notice any spring and ball and did not know it was supposed to be there !
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Roy,
It could possibly be the same spring and ball as used for the engine breather in the timing end of the crankshaft on the 2ľ models - Douglas were good at making use of existing parts from earlier models!
Regards,
Eddie.
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Hi Eddie
Thanks for that. In which case I suppose there is a possibility that pre war spares may have some parts, but I will have to wait until the current crisis is over and the spares service is up and running again. As I say it doesn’t affect the running of the engine, we just have to remember to turn off the oil supply when we park up.
Roy
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More important - turn it back on when you resume your run!!!
Eddie.
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Hi Roy,
my 600 luckily had the spring fitted.
It was broken in two but at least it meant I had something to measure up, and it turned out to be the same gauge as a B string on an old electric guitar that was knocking around.
Just checked the workshop & I still have my first attempt at winding one. As luck would have it my later attempts were no better!
Its yours if you can make use of it.
Mark
(https://www.douglasmotorcycles.net/aa-files/images/aero/2020/Douglas-Aero-Oil-sight-glass-drip-stop-spring.jpg)
[Attachments converted to linked images. 25Nov21 -Doug]
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Hi Mark
That's very kind of you. If you could post it to me I will be happy to refund the postage. I assume you are a club member and my address is on the inside cover of the Conrod under Secretary. Many thanks.
Roy (Staunton)
and yes Eddie - that is my biggest worry. I am parnoid about checking that the oil supply is turned back on before I ride off. A club member well known to both you and I (DR) did exactly that and he tells me he covered 20 miles before the engine seized!
All the best .
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I would be interested to see where this spring fits and how it works. My bike do not have it and I get used to open and close the oil tap since I had it as I was told to do so.
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Hi Eric
Perhaps Aero (Mark) can give us his advice as to how this is actually fitted as like you I don't have these parts fitted to my bike. My understanding is that with the engine running the ball is lifted of it's seat and allows oil to be pumped to the drip feed tube. When the engine is stopped the spring pushes the ball valve back on to its seat and stops the oil flowing otherwise the oil sight window quickly fills up with oil and eventually drains down in to the sump. Even with these parts fitted I am told by those far more expert than me that it is recommended that you still have a tap fitted in the oil feed line from the oil tank otherwise if left overnight some oil will still seep through.
Roy
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Thats a good description of how it works. However I have not found the need to turn the oil tap off. Even if not using the bike for a few weeks the most I have seen the sight glass is half full.
To save me stripping it down to show the gubbins I've marked the spring position in red & the ball bearing sits underneath marked in black.
(https://www.douglasmotorcycles.net/aa-files/images/aero/2020/Douglas-Aero-oil-sight-glass-ball-spring-location-002.jpg)
[Attachments converted to linked images. 25Nov21 -Doug]
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Thanks Mark
It was interesting to hear you say that even when left for a few weeks the oil sight glass was only half full. As I mentioned to Eddie I am paranoid about making sure I've turned the oil tap on before moving off. The last thing I need is a seized engine. Once I get these parts fitted I will experiment with the need for the tap in the oil feed line. If I can leave it on all the time I think I will be alot happier.
Roy
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My memory is really bad. A few months back I removed the assembly and I remember this spring and ball. As for the tap, I am using the wheel on top. I close it and open about 1/2 turn I guess.
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Roy, the spring is on its way.
If you tap the ball bearing into its seat sharply using a brass or alloy drift it should seal nicely.
This is how much oil is in my sight glass after the bike standing for the last 2 weeks.
(https://www.douglasmotorcycles.net/aa-files/images/aero/2020/Douglas-Aero-oil-sight-glass-ball-spring-location-001.jpg)
[Attachments converted to linked images. 25Nov21 -Doug]
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Hi Mark
Thanks once again. If I can achieve the same result I will be happy to leave the in line tap on all the time. Without the ball and spring the sight window fills up very quickly - matter of minutes so I need to shut off the tap even if I'm just stopping for petrol. My son has the same problem with the 500 version he has just finished restoring - see photo attached. He was hoping to take it to this years Annual Rally but sadly as you know this has been cancelled. Never mind there is aways next year so I will keep working on my Aero 600 so I don't show him up! Mind you I've got the bigger engine although frankly there doesn't seem to be any difference in performance.
Best wishes
Roy
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I am now ready to re-install the cylinders.
What is the best, slide the piston and top rings in the cylinder, then drive the piston's axis on the conrod and then drive the bottom ring in the cylinder
Or
Install the piston on the conrod and then drive the piston in the cylinder?
I got a tool to compress the rings but it can't be used as it does not fully open and is too wide.
Also am I happy with a 2.5 grams difference in piston weight?
Any tip welcome one more time.
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Making slow progress on engine assembly.
Still have to adjust for timing where a friend should be able to help me.
As for the tappet adjustment, the book of jhe Douglas ask for .006". Is that still correct although I don't see ay reason to have it changed over the years?
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Hi Eric
I was told .006" exhaust and .004" inlet
Roy
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Anybody knows the wrench size normally required to adjust the tappets? I did not unlocked them while the cylinders were out. Too bad and the nuts are damaged so wrenches fits oddly. Seems to be 3/8 and 7/16...
Adjustments are all over the place.
Edit : it's well 3/8 and 7/16.
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I have a factory supplied service sheet for the Aero models and it mentions 0.006" for the tappets. No distinction for either inlet or exhaust. Nor if the setting was done hot or cold.
By the mid-thirties Douglas were using a lot of Whitworth wrench sizes. So 0.340, 0.4245, 0.520", etc. Earlier you do find imperial fraction sizes. The tappet jam nut us part number 8376, so predates the Aero era quite a bit. That number dates back to the time of the 350EW.
-Doug
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Hi Doug
Is it possoble to post a PDF copy of the service sheet you have for the Aero. The only information I have when servicing my Aero is what other people tell me. Hope you can help. Thanks
Roy
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Roy,
Much of it is the usual palaver about running in and adjustments. Only a little really useful info. I have uploaded it here in the Technical Articles board:
https://www.douglasmotorcycles.net/index.php?topic=8098.msg31144#msg31144 (https://www.douglasmotorcycles.net/index.php?topic=8098.msg31144#msg31144)
-Doug
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Tappet adjustments made a .006".
Cams measured and all are equals.
When I check or valves opening (I am not sure of english term for that, balance maybe?) the valves on 1 cylinder are closing and opening when piston is up for less than 1mm
On second cylinder in same conditions, valVes open for 3mm+
I can't understand why with same cams and same tappet adjustments I come with different valve openings?
PS Doug I sent you an E mail
Eddie I sent you a PM
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Thanks Doug - much appreciated
Roy
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Still working painfully and as time allows on this engine and still finding some weirds arrangements.
I just realised (thanks to Doug) that the tappets were the wrong ones. So I have to replace the rear cylinder exhaust tappet with the front cylinder inlet tappet.
But the latter being close to the engine block, it does not slide off the guide.
Cylinders and pistons are in place but how can I get off the tappet, I assume I have to remove thje guide but how? Is it screwed or pressed in? What would be the simplest to slide off this tappet?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200531_190954.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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Hi Eric,
unfortunately i think you will have to remove the front cylinder to allow you to tap the inlet valve guide out.
Its best to use a brass drift to avoid damage to the indentation slot provided for removal.
The guides are a taper press-fit, and contain an "O" ring to seal them.
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Thank you my friend. I was so sorry I had to take off the cylinder ...
but you can't always loose !
I had a look and saw that the guide was not blocked under the cylinder. So I removed the nut holding the tab that hold in place both guides and with a mild blow on the slot, the guide popped out. I exchanged the tappets and now the valves are opening and closing on .020-.025 gages @TDC on boh cylinders.
I am happy and hope nobody will explain there is something else wrong.
I will push back the guide, do I need to heat the block to secure it or just the clamp holding it is fine?
I did not removed the tappets so it's a previous owner/restorer business. I guess the bike will work much better if I ever can make it work.
But I still move forward, slowly but forward.
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Eric,
Just seat the tappet guide in the taper with a light blow from a soft drift to make sure it is firmly seated. Then apply the bridge clamp. No need to heat the casting. Make sure you install the tappet guides so that you have access to the notches for the next time they are removed. Three have the notch facing the timing cover, but the rear exhaust needs the notch pointing downward so that you can access it via the opening in the casting.
-Doug
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Eric,
I'm glad you had some luck at last.
I had the same problem of incorrect tappet orientation by some previous owner, but on my bike the guides were obscured by the cylinders casting.
I also found that casting completely obscured the breather hole, so the breather system was totally blocked! Maybe it was that way from new or perhaps it had a cylinder change in the past & they never checked.
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Some questions here.
On A, I don't have a washer or anything between the nut and the gear below. Is that OK? And how can I tighten the nut, the engine rotates when tightening.
How tight does it need to be, loctite? Do I have to lock the engine to tighten the nut?
On B, there is a lock washer. How tight and loctite?
On C, I have flat washers, same questions, how tight and loctite?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200605_223406.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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Hi folks
I found my way on B and C above but what about the main A nut?
I thought about holding the crankshaft via the flywheel nut but this may disturb the crankshaft.
I am thinking using a cloth in the gear teeths to lock the engine while I tighten it.
But the questions remain how tight does it need to be?, no washer is OK? and do I have to Loctite it?
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Hi Eric,
when I first reassembled my engine I had no washer behind nut "A" but I later found that without a washer there was no preload on the gears, and they could move slightly, so I fitted one.
I would use Loctite on the threads & stop the crank rotating using the flywheel nut as you don't need to apply a huge amount of torque.
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Thank you for this information. I will get a washer even though I can't see how a washer might pre-load the gears?
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Axial pre-load (clamping force)
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Hi all
On my engine, the timing side of the crankshaft seats in a bronze/brass bushing. Shaft has an helicoidal groove.
I am wondering if it would be wise to use mecanical grease rather than oil in the brass bushing (plugged on one side)? Is grease or oil the best? I thought grease may end up making a solid piece of old grease and prevent subsequent oiling from the engine's oiling system...
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I seem to recall there is an oil feed straight from the pump to that bushing in the timing cover, so best only use oil to pre-lube it.
Might be a good time to clean the multiple oil passageways out in that cover too if you haven't already?
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Good point.
I am having a Ford V8 being rebuilt and I made sure the rebuilder clean and check the oil circuit. Good to remind me to do it there too !!
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Checked the oil system, I blew in the oil arm that brings oil over the conrods and it goes not through. Is it normal as it is kind of backwards against the normal oil flow?
How can we test the pump to make sure it works without taking everything apart?
I tried to turn the pump by hand but it's probably going too slow.
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Eric,
The following post, though for an A31 model, shows an identical oil pump circuit. By applying some oil to the appropriate hole(s) you should see oil pump through. It is a positive displacement pump, so while it may pump slow when turned by hand, it will pump.
https://www.douglasmotorcycles.net/index.php?topic=4288.msg15399#msg15399
This post shows oil transfer from the crankcase to the timing chest, whence it is scavenged.
https://www.douglasmotorcycles.net/index.php?topic=5936.msg21795#msg21795
In this earlier post of your engine one can see the bush supporting the outboard end of the crankshaft. There is a gutter in the timing chest to collect oil and lead it via a drilling to the bush. One hopes it got pressed back in the precise orientation to maintain alignment of the crankshaft axis! And there has to be a hole from the gutter to the bore.
https://www.douglasmotorcycles.net/index.php?topic=5829.msg21297#msg21297
It looks like the bushing interrupts the drilling from the bottom of the timing chest that scavenges oil and returns it to the oil tank. The corresponding part of the bush likely should be relived so that it does not form an obstruction. It should not break through into the bush. It does not provide oil to the bushing and any connection will likely cause the scavenge circuit to suck air in rather than lift the oil.
-Doug
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Thank you Doug
Looking at the 2nd link, I recognise my engine (and then I realised it was Polly's so that's well it) and it already had the reversed front admission/rear exhaust tappets !
As for the bushing you are right, I have well this small port and it's well aligned. I checked for it (as I can't remember such things) after Aero told about it.
In the post you talk about a sheared pin.
I tried the pump, it takes quite a few drops of oils but the oil drips well from the spraybar, turning by hand.
I will test late rthe scavenging portion and try to find out the bypass in&outs.
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Its worth removing the pump & checking the previous owner wasn't having a bad day gasket making
(https://www.douglasmotorcycles.net/aa-files/images/aero/2020/Douglas-Aero-Oil-pump-gasket-issue-001.jpg)
[Attachments converted to linked images. 25Nov21 -Doug]
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Checked the oil pump, gasket was nice and neat. Stayed well in place.
I am in the final stages of closing the engine, waiting for light Loctite to "glue" the nuts holding the plate over the distribution gears.
I used a good amount of new motor oil on the parts. Is there anything special to do when closing the engine to help in pre lube before starting the engine?
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These engines are basically a wet sump with pumped recirculation, so its a good idea to start off with a quantity of oil for the crank to sit in & splash around the bores. I haven't measured exactly how much sits in mine but I'd estimate 200ml
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You will also want to pour some oil in the timing chest. It is meant to pool up to the depth of the weir before spilling over and being scavenged by the pump. The depth ensures the teeth of the lower cam gear dip into the oil. Oil vapor passing through from the crankcase chamber normally maintains the oil level. But with a newly rebuilt engine it would take time for the oil level to build up and the gears might run dry in the meantime.
-Doug
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I was advised that even when doing an oil change to remove the dynamo and pour in about 1/4 pint of oil into the timing chest before restarting the engine for the same reason.
Roy
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What kind of gaskets do we want here?
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200712_183759.jpg)
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20200712_182907.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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Eric,
Hard fiber washers, just as shown. Red is the traditional color.
-Doug
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When I had the cone rebuilt on the crankshaft, the guy that made it also made 2 new washers to place under the bolt that hold the crankshaft pieces together.
Those washers has tabs that you fold up against the bolt head.
I recently saw a picture of one of those washers on a crankshaft except it had 2 tabs, one that goes up against the head, like he did for mine and one (or maybe even 2) that bends down against a flat on the crankshaft.
I would like to show him this picture of a 2 tabs washer but I can not find it on the forum. If anyone could point it out for me I would appreciate.
Then I will open a discussion with forum members and the guy that made mine and see if a single tab washer will work...
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Well no way to get this picture, can't find it so I'll go by words...
On the crankshaft, there is bolts. Under those bolts we have washers. Those washers uses 3 tabs, 1 goes up on the bolt the other 2 go down on some flats (that's what I saw on this picture)
When the machinist rebuilt the cone on the crankshaft, he cut washers but made only 1 tab that goes up on the bolt. He said this is common practice, a known way to make these washers. The washer being held down by bolt pressure and bolt can't rotate because of the tab. Makes sense but at this time I didn't knew 2 tabs were to go down.
So my question is to know if I will it work without the 2 down tabs?
This has been going around my head for a few weeks and I stopped putting the engine back together until this is answered as I don't want to go further down the road if I have to climb back later.
At this time engine is almost closed, just have to bolt in timing cover...
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Eric,
The two outer tabs don't have to necessarily bent down; they can remain flat. They just engage in the slot cut into the face of the crank throw. The center tab bends up, against a hex flat on the bolt. Both are needed, one to react against the hex, and another to abut against a fixed position. Your mechanic is wrong. Without, the tab washer could be carried around with the bolt head as it loosened. If friction was sufficient to stop it, plain washers would work as locking washers.
-Doug
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Dear contributors on this thread. I am Gerd from Germany and I own a Douglas Aero 500. I bought the bike 2 years ago in running condition. Unfortunately the failures became larger and I stopped working on it. Reading these pages encouraged me using the Corona time for doing a new start. Many thanks to all contributors. It is nice conversation on Douglas Aero. Especially the questions from Eric were very useful in combination with the answers. They showed a wide range of problems, which I detected also. Don't be surprised, when I am coming with with new questions. I am stuck with the gear box now.
Best reagards
Gerd
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Gerd,
There was a 4-1/4 page write-up in the Jan/Feb 2021 issue of the New ConRod magazine on the evolutionary changes of the 1936-38 Aero Douglas heavyweight models. I will be re-printing that here once I gather some additional supporting photos.
-Doug
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I have a simple question on the four speed gearbox. This one has a constant mesh kickstarter. The ratchet is fixed to the main shaft and receives the full torque from the kickstart lever. Is the ratchet screwed to the mainshaft?
It looks like for me. But I was not able to unlock it for getting the main shaft out of the box. There were three holes in the ratchet, which I used (are those original?). The small tool (picture) was put on an impact driver. The ratchet was heated until oil was flowing out of the crevice and then the impact driver put on. It did not work. Has somebody a better method?
Regards
Gerd
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Gerd,
Yes, it is threaded on. The three holes are factory, and the means for installation and removal. It helps a lot to have the face of the pin driver cut back to match the face of the ratchet closely. This reduces the cantilever of the pins. It is surprising that the small amount of deflection bridging the gap significantly diminishes the effectiveness of the impact driver in jarring it loose.
Remember it has had years of heavy boots stomping on it to tighten the thread!
-Doug
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Doug,
thanks for the information. One night I thought the heavy load from kicking should not be put on a thread. I will redo the tool and do a next try. The holes in the ratchet are so demaged, that I believe my preowners did not succeed.
Gerd
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Doug, I am very interested on the report from the LDMCC. Unfortunately I am not a member of the club anymore. Chris told me once, that the club gets loss due to foreign members. I will show road tests of Douglas Aero in comparison to BMW R5. The Motor Cycle Magazine did it in one issue.
Thanks
Gerd
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Doug,
I have redone the tool for removing the ratchet. It is much stiffer and worked well.
Gerd
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Hi Gerd
I am glad my miserable adventures are benefiting others enthusiasts.
I haven't touched the engine since august as I am kind of disgusted because it took me months to close the engine just to discover when almost finished that I have to open it again to replace a small washer that was not made correctly. I am asking a lot of (stupid) questions just to find that on one of the rare parts I didn't asked, there is a mistake.
I see you are working on the gear box, I still have to investigate in this area as the kick was slipping back in the old days when I was riding the bike. Hopefully it's just a matter of replacing the spring and I won't have to open the whole box to replace it.
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Hi Eric,
I used the Corona time for working on the Douglas. I think next summer we are riding again. I opened a post on the four speed gear box. You have perhaps seen it.The lower big nut on the outside of the kickstart cover is for dailing the clearance of the ratchet. When I inspected my kickstart mechanism, this nut was screwed fully home. It should be set, that the ratchet wheels are just not touching during normal running. The picture is showing what is inside the cover.
Happy tinkering
Gerd
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Gerd,
I think you are mistaken in your reasoning regarding the operation of the kickstart. Whilst you may be correct in thinking that the ratchet needs adjustment - this shouldn't be achieved by backing off the securing nut. That adjustment should be achieved by selecting a suitable thickness facing washer for the bendix assembly, so that the nut can be fully tightened. Leaving the assembly loose will result in the fitted length of the spring being too large - thus reducing it's operating pressure. It is this pressure which persuades the gear to ride up the bendix (instead of the sleeve turning with the gear). Later postwar gearboxes have the same arrangement, and they suffer with the kickstart not engaging when the spring gets tired.
Hope this helps,
Regards,
Eddie.
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Eddie,
Thanks . That makes sence to me. I will open the kickstart cover again and and will add a washer. A rough guess of the thickness may be received from current position.
Gerd
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Thank you for pointing out your gear box thread. I usually go to "Show unread posts since last visit." to see what's new and this gear box thread never appeared there !
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Eric,
After clicking "Show unread posts since last visit", if you look in the bottom right corner of that page, there should be a button marked "ALL UNREAD POSTS" or "ALL UNREAD TOPICS". That will bring up a full list of everything you haven't read.
Or try this link and then bookmark it - All Unread Posts - Douglasmotorcycles.net (https://www.douglasmotorcycles.net/index.php?action=unread;all;start=0)
This is what I use to check for all unread posts each day.
Dave
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Thank you Dave.
Now I have 55 PAGES of unread Topics !
But in any case this gear box topics probably appeared earlier on the unread post since last visit and I probably missed it...
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Eric,
:D.... Look for a button that says "MARK ALL MESSAGES AS READ" or similar and they won't appear again. Or you can select a few then press "MARK SELECTED READ" to mark a few as read.
Dave
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Well after just 1 year with the engine set aside on my bench as I was disgusted to have to re-open it after having spent months to close it, I finally get it to this washer with a single tab holding the crankshaft together.
I would be glad if I could get a picture of the correct washer so I can show it to the guy that will cut it again for me.
(https://www.douglasmotorcycles.net/aa-files/images/eric-s/2020/20210808_120425.jpg)
[Attachments converted to linked images. 09Dec21 -Doug, Admin]
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Looks like this.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2021/Aero-crankbolt-tab-washer.jpg)
One part of the washer needs to be keyed to something stationary and the other bent up against the hex. You should be able to get the dimensions from the existing features on the crankshaft.
-Doug
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If you don't want to dismantle, you could slot the tab on the dotted line and fold down into the slot at the arrow. Assuming RH thread.
Leon
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It seems to me that the effectiveness of the tab washer (either Eric's or the original) is very much dependant on the final orientation of the bolt head. In this case, I would prefer to rely on modern technology and use Loctite to prevent it working loose - use just a plain washer to ensure the bolt doesn't become threadbound before clampng up the crank web.
Regards,
Eddie.
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I had the same thought of cutting a slot and make a second tab.
I may also remove the bolt and add Loctite.
Thanks for the help
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The metal will be weakened by bending it back down, and may break off in the future, so personally I'd start again for peace of mind. Loctite is a good idea, whether with or without the tabbed washer is up to you.
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At last I re-opened the engine, removed this washer and had a new one that will have 1 tab on nut and one on crankshaft.
2 questions.
I assembled the engine with .4mm papper gasket. Can't find it easily. Does it make a large difference if I use .5mm
I had very little play on the crankshaft, can't remember the figure but it was on the low side. Is .1mm going to make it too wide?
Then (I may have asked that earlier but forgot and can not find it in the previous pages)
Do I have to use Loctite on the bolt holding the crankshaft together on this tabbed washer or the tabs are enough?
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At long last my mechanic finally made this 3 tabs washer. But I guess he went in a bit too much creativity.
I don't feel safe using it as is.
Any thoughts?
Should I ask him to make it AGAIN !?
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Afternoon Eric
Basically Eric put the washer in the bin! and start again.
Attached is a picture of what you should have, all be it that the Centre tab has gone. Everything fits neatly within and over the machining of the web so use that for your dimensions.
See Doug’s previous message and sketch also.
Steve
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Exactly what I thought.
I did not draw a sketch and thought my instructions were clear enough.
I'll have to have him make a new new one...
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Back in business !
I finally received the parts. He did cut 2 in a piece of metal I sent and 2 more.
He left the tabs longer and uncut so I can cut them.
I have 2 made in stainless .074"/1,88mm and 2 in galvanised steel .059"/1.5mm thick. Not sure which ones i will use.
Now I need to make sure how to make it tight.
I cut a wrench to fit nicely over the hex head. Question is how can I tell if the bolts are tight enough? Is it good if I tighten the bolts as good as I can and bend the taps.
Is there any way to make the bolts tighter?
Use Loctite? Although this will not make nothing on torque and tabs are here anyway to hold the bolt...
Any advise is welcome before I jump back in there.
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Well as I had no reply I decided to follow Eddie's advise and use Loctite.
However when I clean and prepared parts, I noticed a play in the flywheel end of the shaft and it moves around by about 1mm at the tip (where I put a rule on the right of the picture). There is some play around the 3 pins/dowels.
Once tightened there is no feelable play of course.
Should I try to force on the female holes for the pins to deform them, use larger pins, compress the pins to try to make them fatter, apply more loctite there (being cautious none goes down to the conrod's bearing) or any other way to make things tighter?
Would it be enough to eat up the play before tightening and that would be good enough?
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I went to the local machine shop for advise. He looked at the parts and did not felt comfortable at doing the work so I have to go to another shop a bit but have to wait until the gas strike we have in france now is over...
We thought that the best would be to drill the 3 holes in the parts a bit larger and install new larger dowels/pins. That should take care of the rotational play.
However he was also concerned with too much play between the 2 parts on the round section leading to an axial play.
This was just on the flywheel side. We'll have to check the other side too.
AGAIN, any idea or advise here is welcome.
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Hi Eric,
Almost impossible to comment without having the crankshaft in hand - I think you need to find a local "classic expert" who is competent to do the job. Tricky these days.
That said, it all sounds very worrying, both the problem and your proposed solutions. Building the crank was traditionally the work of a "fitter", who was expert at getting pieces of metal to come together with appropriate clearances and alignment. Tapers have to fit into their seats with precision, both surfaces (ideally) have to be unmarked, and once together - even before they are tightened - there should be no movement in the joint at all. So if you have 1mm of play where I've marked it below (if I understand what you're saying) with the crank assembled and somehow tightened there is a serious problem that no amount of loctite, pinning or tightening will fix.
Tightening the the bolts/nuts serves to pull the assembly up dead tight, and at this stage some very careful alignment goes in to make sure that the two mainshafts are running completely true - they need to be both parallel and on the same axis. The combined run-out should ideally be less than 0.001" or so, which takes a mix of expertise and good fortune, not to mention appropriate tooling (a crank jig or at least a lathe) and measurement tools (best to have at least two dial gauges). Aligning a crank is amongst the most difficult jobs in restoring an engine.
Sorry to make it sound difficult, but it is.
Good luck.
Leon
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Eric,
You can bore and fit oversized pins, perfectly valid solution and has been done before. However if the cylindrical fit of the crankpin is slack in the crank throw then it does not matter how tight the pins and the bolt are, it will work loose under the influence of the impulse loading and flexing of the components. There ought to be some sort of press fit, light to moderate, without the pins installed. If you can rotate the the joint without thumping it smartly with a mallet then I think the fit is stuffed. Loctite is amazing stuff, but I would not trust it to fill up the gap and remain durable if you can rotate the joint by hand. Unfortunately if the joint is stuffed there are not really any easy solutions other than replacing or somehow building up the journal or/and re-machining the hole (which is probably stretched.)
-Doug
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Finally I was lucky that I had to open this engine again.
Leon, you're right, the play is where you put the yellow arrows BUT the play is there only when there is no bolt and parts are just fitted together. If I tighten the bolt, there is no play. I got my comparators and I came to a play of roughly .030"/0,75mm on the same spot. See 5th picture below.
I checked the timing side. 1st picture. No play visible or feelable. Seems to have been filled with some kind of Loctite but the engine ran with it and it did not moved. I will left it undisturbed or should I open the can of worms?
Made some pictures of the surfaces on Flywheel side. Pictures 2-3-4
I also measured the play the best I could by putting the comparator on the end of the flywheel and pulling on the shaft to pull up the part under the comparator. Comes to about .040"/1mm. With pins in place, it's about .005" less. Picture on next post.
I think this is way too much. The easy way would be to sleeve it but the holes for the pins would require a 3 parts sleeve unless the part under the pins if long enough to allow for a castle style sleeve (or using shorter pins).
I have to visit this company maybe on Monday. They are a machine shop but work only on engine. All kind of engines from all periods and just that. So they will understand the concerns there and may come with a viable solution.
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Last picture
Sorry they are all a bit big !
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Yes, you will have to talk with them. Given how the timing side big-end pin looks, you should consider doing both sides.
Doug's advice is excellent and based on a lot of experience, so be sure to pass this on to the man at the shop. They may talk about hard-chroming the pins and regrinding them to fit in slightly-opened crank webs. Remind them that the rollers in the big end run directly on the pin, which may be more than hard chroming can tolerate. (Hard chroming works well with plain bearings.)
Another option may be to fit an available needle roller bearing in the big ends, with an outer pressed into the con rod and an inner on the crank pin. Perhaps someone on the forum has done that in this type of engine?
Also remember that any opening out of the crank holes has to done to within better than 0.001" otherwise the crank will never again run true.
Leon
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Hi Eric,
On a slightly different tack, do you have the original magneto for your Aero? If so, could you let us know the numbers on the brass plate on the magneto? I'd expect something like M2 AD4 7x869xxx
Thanks
Leon
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Leon
Never noticed this plate, it was all black, covered with dirt.
Sorry can't download picture
It says
TYPE M.2 / AD4
7F 870015
Hope this helps.
Will try again with picture later
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Perfect, thanks. The magneto dates from June 1937, so presumably the bike was a late-season build.
Leon
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Went to this engine machinist today.
He confirmed what Leon said, it's going to be difficult.
I will save the comments about English engineering,🤪
He knows how to do it but it would cost thousands and he is not really positive about the results.
Maybe some are interested in repairing more crankshafts and we could save on quantity?
What are the chance to find new parts? Do the club carry any?
He could start with a new middle part where the dimensions and shape of the studs would be in good condition so that he can start from a part true and correct but where can I get one?
Then Leon talked about tapers on the journals. We did not felt there is any.
Also the Conrods' bearings are running on a sleeve over the journals. Is that original or modified?
He said it would have to be eventually balanced but as there is no adjustments...?
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Received the list of spare parts today.
I can find the head gaskets and kickstart spring but nothing regarding the crankshaft or parts.
What can I do ???
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Mmm... "thousands" eh? That's a lot.
I once got quotes from plumbers to move a toilet from a different room into a bathroom and install a new basin. Thousands. Then I pulled of a couple of sheets of plaster off the wall and got a quote from another plumber to put a pipe from here to here and join it in here. Hundreds.
There are companies that could hard chrome the crank pins and re-grind them oversize - certainly the parallel ends (with the pins) need doing, not clear about the tapers on the outer ends (if there are tapers). This is their bread and butter and wouldn't be too expensive. I'd guess 100-200 pounds, but maybe more these days. There are also toolmakers who could open the holes in the crank with appropriate accuracy, again 100-200 pounds? (just guessing). Maybe they could make new pins for less than the cost of hard chrome + regrind. Then sort out big end bearings, with an inner pressed onto the crank pin and an outer pressed into the rod - another couple of hundred pounds.
So it could be done, and "you" could do it by taking the various jobs to the people who perform the individual tasks. But to be on top of the over-all job, you need to be the expert measuring and specifying exactly what you want so the job will work overall. It's hard.
This is why your man says "thousands" to do the job. Is Alpha Bearings still doing jobs like this? Worth asking. Converting currencies (I'm in Australia) I'd be very happy is someone quoted me 1000 pounds, and wouldn't be surprised by 1500. As a non-expert machinist, but a pretty good measurer and specifier, I reckon I could do it (for myself) for half that, using expert services to do the actual jobs. Of course there are restorers who are also expert machinists as well as expert measurers and specifiers, and they would do the job (for themselves) for a lower cost again. But what value their expertise, machinery, and time? We're back to "thousands"!
Leon
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I would be wary of getting the 'crankpins' hard chromed - partly because I don't like this process on this sort of application, and secondly, because it would render it almost impossible to re-ream the holes for the locating pins.
Before farming out any work, you need to carefully assess the individual operations, and what you have got to work with.
At the moment, you have 3 pieces of a crankshaft that need to be built into a complete unit - the 2 end webs and the centre section. Any machine shop with a decent sized centre lathe and toolpost grinder should be able to set up the end webs on a faceplate and grind the bores for the crankpins - they just need to make sure they get the correct throw on each web. The next operation will be to build up the diameter of the ends of the crankpins on the centre web (the centre web and crankpins are one piece). There is a relatively new method called 'Laser welding' that doesn't overheat the component, or affect it's previous heat treatment. With the pins built up, the centre web could then be mounted on the faceplate, and the pins ground to give an interference fit in the end webs (say 2 to 2˝ thou) - the leading edge will need to be slightly radiused and polished to facilitate pressing into the end webs. When setting the centre section up on the faceplate, it will be possible to clock up the actual bigend journal to make sure you don't alter the throw.
You should now be able to re-assemble the crankshaft (relying on the press fits while it is being trued up), re-ream the holes for the locating pins, then refit the 2 large bolts and tab washers.
Most of this work should be possible by any engineering machine shop (even a well equipped hobbyist) - the only specialist task is the laser welding.
So, there's a little food for thought - hopefully it will help with the recovery of your crank!
Regards,
Eddie.
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Eddie I wonder what role the pins play if there is a good interference fit already? "The Scotch key" featured prominently on very early engines (and Jardine gearboxes) but they look a bit out of date here?
Laser welding sounds interesting.
Leon
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Leon,
The pins were probably the most cost effective way of ensuring the crank could be re-assembled reasonably in line - should any remedial work be needed. Evidently, the holes were virtually hand drilled - so every crank was unique, and parts were not easily interchangable!
Yes, Laser welding is amazing. One of our local LDMCC members had the front cover of a Lucas magdyno modified to fit in the back of the timing chest on a Speed Special. The weld was incredibly neat, and at the end of the welding, the cover could still be picked up in a bare hand! I'll look out a link to the company that specialises in it.
Regards,
Eddie.
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Hi Leon,
The company local to us that does the laser welding is E.M.P. Tooling Services - their website is:- e-m-p.biz Have a look - it's amazing what they claim to be able to do!
Regards,
Eddie.
P.S. They have offered to give LDMCC members a guided tour of their workshop - I'm just waiting for the Club to make the necessary arrangements!
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Wow - I read this page and my heart beat faster! http://www.e-m-p.biz/classic-cars/
It's great that they're interested old car/ bike stuff. Not sure if there's a laser welder near me, but I'll certainly be looking next time a problem comes up.
As you say, might be an ideal solution for the Aero crank pin.
Leon
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Thank you for the food for thought provided here.
Gonin Moteurs that I went to are dealing with engines only. One day I asked them, looking at the piles and racks of engines in their workshop, how many they have. He told me they usually have around 250 engines in the queue. He has lot of experience but of course not with Douglas. What I like is he do not brag around being the best even though he machines parts for the whole country ( and he's 30mn from me)
Now I went there without warning and spent 15-30 minutes so he had not much time to think about.
He actually told me about laser welding...
His concern is to get good references to start with that's why his conclusion was for me to try to get a good center web so he can start from something true and correct.
Otherwise he feared he would have to spend too much time making jigs and alignment
I have to call him to discuss further should I get anything new.
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I called the guy that did the cone a couple of years ago. He is 1hour away and quite busy but returned my call and is willing to help. I will visit him in a few days.
A couple of questions in the meantime.
What are the screws on the center web? One each side.
Is the conrod well installed on the journal through this sleeve?
Is this cage bearing an original set up?
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Eric,
The slotted screw is a plug for an oil drilling. This was used on the 1935 engines that feed oil in through the end of the crankshaft. The 1936-38 Aero engines oiled the crankshaft via an external spray bar and grooves on the center web that led oil in through the sides of the big end bearing. You seem to have a mix of 1935 and 1936-38 components, as initially related here in this and subsequent posts:
https://www.douglasmotorcycles.net/index.php?topic=6434.msg27351#msg27351 (https://www.douglasmotorcycles.net/index.php?topic=6434.msg27351#msg27351)
The bearing cage is the original setup and can be seen in earlier posts like this one:
https://www.douglasmotorcycles.net/index.php?topic=6434.msg27357#msg27357 (https://www.douglasmotorcycles.net/index.php?topic=6434.msg27357#msg27357)
-Doug
[fix typo. 01Nov22 -Doug]
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Thank you Doug
I remember having discussed before this engine being a mix but I don't remember having asked and received replies. Thank you for pointing out. I think I should read again the whole 9 pages and make notes!
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I spent some time printing and reading the whole discussion about this engine. Refreshed my memory !
The crankshaft is due to a company that do laser welding. The company that did the cone on the flywheel side will do the assembly.
We are going to laser weld the 2 journals that goes through the bearings (so we'll have neat surfaces and tight fit), and the 2 inner journals (?) that goes on the center web so the fit on the center web is tight. Then he will balance the whole thing and ream to install new pins.
He's not confident about the quality of the job as the design is not sturdy for him. But I should end up with a tight, straight crankshaft, as good as from the factory.
When I removed the (loctited) other side, I was surprised to find the fit to be better than on the flywheel side and the cage bearing being "solid".
Which then bring the question as to know why the first bearing I removed felt apart. I thought it was normal but I fear it might be done?
On this same size, I had no way to remove the sleeve that goes under the cage bearing. Loctite made its way in there. I heated it reasonably but no way to grasp it out.
Should I take it out?
Then I found some kind of washer. Did not had any on the other side.
When closing the parts over the cage, I still have a .013" play so adding a washer makes no sense...
So day's questions :
1. Should I replace one or both of cage bearings?
2. Should I remove the sleeve?
3. Is there any place for a washer?
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On the center web, I see on one side only a hole per the picture below where I slid in a wire.
What is it for and is it normal I don't have it on the flywheel side?
-
I would like to read some advice from the specialists here before I can proceed with laser welding...
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Hi Eric,
Your questions are hard to answer without having the crank on the bench for inspection. That said, the rollers and the sleeves both look marked and worn, which for a roller big end is no good. You can verify this by measuring and close inspection.
The rollers can and should be replaced. If damaged, it might be possible to lightly regrind the outer surface of the of the sleeve on the pin and the inner surface of the conrod bearing (do the rollers run in the rod, or is there a pressed-in sleeve?) and fit oversize rollers, but replacement of the lot would be best.
Getting the correct end float for the big ends is part of the setup, although if the con rods are straight (this needs to be checked carefully) the exact end float is probably not critical.
I'm not sure what that shim is doing. But then, I would have said that the bearing cage could not possibly be original (quite the sparsest set of rollers I've seen in a big end), and the three pins... ghastly. A crank like this would be ok in a bike from the early 1920s, but it looks very out of place in the mid 1930s.
I'm not sure when pressed-up cranks came into common use, but my guess would be that a Velocette of the era would just have the crank pin pressed into the flywheels? Pressing the crank pin onto a shoulder is a solid way of doing things, but there is a problem if - as in the Douglas crank - there is a sleeve over the pin. If the pin has a shoulder, how long should the sleeve be? It is impossible to get both the sleeve and the shoulder to bear equally on the face of the flywheel/crank throw. I've recently done up and engine (a Spacke DeLuxe) with this problem (and more), but it was a 1913 design, not mid 1930s!
Good luck,
Leon
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Leon
thank you for taking time to reply
I know it's difficult to have opinions based on pictures. Just try to gather informations...
Do I have any chance at all to get new cage bearings anywhere?
Can you explain what the end float is. Is that longitudinal play in the crankshaft?
What do you mean with the sparset set of rollers you've seen?
The 3 pins on both side will be replaced and holes reamed.
The guy I met that'll do the machining worked on a french Terrot from 1910s. He said the crankshaft was built like a modern bike (pressed-up crank?) with a press fit of the shaft's different parts.
The sleeve on the timing side is locked with Loctite and proved difficult to pull. Would you remove it for inspection or leave it here?
Also per my post #449, I see a hole on just one of the 2 pins of the center web. Is that normal? I can't see any (oiling) use for this hole.
Thank you again.
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Eric,
The holes in the crank pin and the web are for the 1935 oil delivery method from the timing side end of the crankshaft. They would not be present on 1936-38 engines.
There are not supposed to be shims alongside the crank pin/conrod. The side or axial clearance Leon refers to is between the sides of the conrod and the crank throws. The width of the conrod big end eye should be about 0.010" narrower than the width between the throws. This is so that as things expand and flex (especially flex!) the conrod does not get nipped on the side. Also while the conrod should be checked to make sure it is straight, the reality is there is always some small amount of imperfection that could cause the conrod to want to take a position minutely off-center. If you try to constrain it, that creates friction and hot spots.
The rollers in the photos, while not totally trashed, do look like they have had a hard life and need replacement. The crank pin race does not look too well either, but hard to judge from a photo. It might lap in o.k. I would think that the fella doing the laser welding would want the crank pin race removed to get it out of his way, even though it is adjacent rather than under the area he will be working. If the conrod needs lapping, you might need to make a new, oversized crank pin race. You would then also need to bore out the bearing cage as it rides on the crank pin.
Spheric-Trafalger Ltd used to sell bearing rollers in Europe, and I ordered 20k of the 3/16 x 3/16, 1/4 x 1/4, and 10k of the 5/16 x 5/16 while the getting was good twenty years ago. While their metric rollers were made in Europe, the imperial sizes were made in India. Hence ordering a large quantity as you need to sort through with an accurate micrometer and size them in lots by diameter. You do not want to mix diameters greater than 0.0001" deviation. That aside, they did not offer oversized rollers as was once available years ago specifically for the motorcycle trade to enable reconditioning and rebuilding of big end bearings.
-Doug
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What do you mean with the sparset set of rollers you've seen?
By sparse I mean the rollers are well spread out. There are 10(?) pairs of rollers in the big end, yet there looks to be room for closer to 20 if the "crowded roller" system were used - usually a cage would have the rollers as close together as possible. More rollers means more contact points means less wear...
Leon
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Leon
the bearing cages I have are the same Doug showned on the picture on post #191/page 4 here. And they have well 10 windows each, holding a pair of rolls for 20 total per bearing.
The crank pin race (I called sleeve earlier) on the picture is oily and dirty. It is in good condition even if one can see the balls' paths with a different shade on the surface. Surface is smooth and flat.
I was concerned as the bearings assemblies were different. One fell apart and the other one kept the rolls in when removed (probably barely). I thought that one was done and should be replaced as an assembly. Now I understand that we can replace just the rolls. I will check and measure them with a micrometer and/or will source some new replacements.
Doug talked about conrod needing maybe lapping and then a new crank pin race. I did not planned that but will check with the machinist here.
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Yell if you need oversize rollers - I have some; not all sizes but I can look.
Leon
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I measured the balls with a micrometer (in inches)
I come with a stuborn measure right between .2505" and .2510". Not wandering between those 2, just pointing all the time at the exact same spot, around .2508".
So I would say they have been replaced not so long ago.
From there I will check with my man after laser welding and see if the conrods need any lapping...
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Waiting for the welding to be done.
I managed to remove this loctited sleeve.
How does it work, is it turning around the stud and the bearing is turning around on the sleeve or is the sleeve somehow locked in place and only the bearing is turning around?
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Hi Eric,
No, the sleeve certainly doesn't rotate on the pin; it has to be fixed in place with the rollers working on the outside. From the look of your photos, the sleeve is designed to be a light interference fit on the pin, and it is sandwiched between the two cheeks of the crank when the hex bolt is done up tight? At least it's easy to remake if worn.
Leon
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Just got a call form the welder.
The holes that need to be welded (where the 3 pin holes are) are not accessible with the laser machine (or whatever it is) so they will TIG weld it. He's quite conscious of the heat problem so they will use small rods, alternate one part and the other. The stud is short and massive so it should not be a problem and they just need to have very little material added...
Good point is I am saving money.
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I got the parts back from the welder a few weeks ago and now they are with the machinist. Quite nice chap but overwhelmed with work... Should not be long before he can work on them now.
One point I neglected is the kick. When I was kicking to start the engine (back in the days ...) the kick was slipping so I guess there is a problem with the spring.
My question is (I haven't looked at it lately) how can I access and check this spring?
Is there any care to have when opening the gear box. Is it better to do it on the bench? I assume it would be.
Beside the spring what can be wrong?
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The spring just returns the kick start, Sounds like the helical thread on the Bendix is gummed up. Use a light, non-coagulating oil or a dry graphite lube on helix. Can be accessed by removing the end cover of the gearbox without removing the 'box from the frame, One of the bolts secures the kick start spring, so it is a good idea as you slip the cover off, you jam a bolt (or rod) in the hole to follow up and capture the spring. That way you don't have to worry about unwinding and rewinding the spring.
-Doug
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Doug
we have the kick that just need to be pulled/extracted.
Then we have 5 bolts about 10-12mm and 1 larger at around 15mm. What this larger bolt holds there?
Is it one of the smaller nuts that hold the spring?
Anyone has a picture of what I may be expecting there?
Will I find gear box oil/grease under the cover or is it dry? Do I need to be ready with a new gasket under the cover?
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Eric,
I do not have the time at the moment to take a gearbox apart and photograph it properly, so will have to make do with what images I already have on the computer.
The area for the kick start gears and spring is separate from the main gear case and is basically dry. There should be some grease on the gear teeth, but otherwise there is no need and some detriment to packing the compartment with grease. There is no need for a gasket.
The fist picture shows the cover removed and the Bendix in place.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2023/kickstart-1.jpg)
Next with the Bendix removed. There is no need to undo the large nut on the outer face of the case. It supports the stub shaft the Bendix operates on.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2023/kickstart-2.jpg)
The kick start spring happens not to be in these particular photos. Also missing is an aluminum hub that slips over the kick start quadrant axle to prevent the inner most coil of the spring from collapsing too much. But the following is a picture of a 1932 type 4-speed with the spring in place. While not exactly the same as the 1934-38 gearboxes, it uses the same idea. The end of the spring loops over one of the cover retaining studs. As you tease the cover off you will see this. Stuff a bolt into the same hole and slide the spring eye off the stud and onto the bolt as you remove the cover. The end of the bolt retaining the spring is indicated by the arrow.
(https://www.douglasmotorcycles.net/aa-files/images/doug/2023/kickstart-3.jpg)
There are some pictures of the other face of the compartment earlier in this topic:
https://www.douglasmotorcycles.net/index.php?topic=6434.msg33372#msg33372 (https://www.douglasmotorcycles.net/index.php?topic=6434.msg33372#msg33372)
and here:
https://www.douglasmotorcycles.net/index.php?topic=6434.msg33533#msg33533 (https://www.douglasmotorcycles.net/index.php?topic=6434.msg33533#msg33533)
In the latter the post for the Bendix has been removed, but typically there is no need to do that.
-Doug
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Thank you Doug but I am not that desperate that I would ask you to open a gearbox for me!
Much usefull as always. Feel more confident now. It definitively helps to see what to expect, can save time later especially for me as if I am a specialist at anything, it's only at making mistakes !
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Doug,
I have redone the tool for removing the ratchet. It is much stiffer and worked well.
Gerd
Sorry to jump
On an old thread but how did you hold the shaft? And how tight was it in the end?
Thanks Neil
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At last I removed the cover.
I was not expecting grease here as Doug said. Is it possible that this grease migrated from inside the gear box?
I don't see either the "aluminum hub that slips over the kick start quadrant axle to prevent the inner most coil of the spring from collapsing too much". Do I need it?
I can't see anything wrong so I assume the bendix and kickstart quadrant were not timed correctly. It seems the kick was pushing too much the Bendix and was loosing contact.
In the picture I adjusted it so it is on the first teeth. I didn't saw how it was originally as after my first try the Bendix went out.
I can't understand the relation between the bendix and the "crown" on the gear box. There is so much axial displacement of the Bendix, there is probably a very short kick movement after the Bendix engage in this crown!?
So how can I time the 2 gears and is there any other visible problem here?
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5 days later, it looks like of I have some grease leaking out from inside the gear box. Does that need to be adressed?
I was looking at the way I timed the 2 gears together. I thought it maybe safer to add 1 tooth further in?
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Re-assembled the gear box cover.
Once the 2 sprockets engages together, the mobile sprockets can't move out any further and then the sprocket/threaded shaft assembly continue to turn (as long as the kick moves) while slipping over the inner shaft so sprocket and kick's gear kind of self adjust. Then the initial position of the gear seems not really important.
Tested by hand (engine removed) and holding the sprocket shaft with a wrench, it seems to give a slipping feeling only when the teeth of the 2 sprockets hits each other "hi-ground" and slip just a little to reach the next tooth.
Can't remember if this was the feeling I had when I was starting the engine...
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Hello there
I made a mistake and need to have my Douglas aero tank repainted
Chrome is rusted on the rear so may have it completely re-chromed &re-painted
Any Adress in UK or Europe?
I am in France