Author Topic: Douglas Aero 1937  (Read 3427 times)

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Offline Eric S

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Douglas Aero 1937
« on: 21 Dec 2016 at 22:14 »
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

Offline Doug

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Re: Douglas Aero 1937
« Reply #1 on: 23 Dec 2016 at 05:02 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #2 on: 24 Dec 2016 at 08:20 »
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
« Last Edit: 24 Dec 2016 at 08:46 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #3 on: 24 Dec 2016 at 23:49 »
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: http://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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #4 on: 07 Jan 2017 at 10:48 »
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.

Offline oily bloke

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Re: Douglas Aero 1937
« Reply #5 on: 07 Jan 2017 at 12:20 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #6 on: 07 Jan 2017 at 17:56 »
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?
« Last Edit: 05 Feb 2017 at 16:42 by Eric S »

Offline oily bloke

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Re: Douglas Aero 1937
« Reply #7 on: 08 Jan 2017 at 07:47 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #8 on: 21 Jan 2017 at 17:51 »
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?

Offline Doug

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Re: Douglas Aero 1937
« Reply #9 on: 21 Jan 2017 at 18:29 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #10 on: 21 Jan 2017 at 18:36 »
Can you send a pictures of yours?
Mine is also a plain hex head bolt.

Offline Doug

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Re: Douglas Aero 1937
« Reply #11 on: 21 Jan 2017 at 20:37 »
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.



-Doug


[Update image path.  22Sep17 -Doug]
« Last Edit: 22 Jan 2017 at 17:51 by Doug »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #12 on: 21 Jan 2017 at 22:01 »
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".

Offline Eric S

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Re: Douglas Aero 1937
« Reply #13 on: 22 Jan 2017 at 09:18 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #14 on: 22 Jan 2017 at 17:49 »
The four examples that I have seen just have a hole.



At the front, as you probably have seen, there is a little amount of adjustment possible for the engine.



-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #15 on: 28 Jan 2017 at 12:21 »
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?

Offline Doug

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Re: Douglas Aero 1937
« Reply #16 on: 31 Jan 2017 at 19:55 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #17 on: 02 Feb 2017 at 19:14 »
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.


« Last Edit: 06 Mar 2017 at 12:14 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #18 on: 06 Feb 2017 at 21:40 »
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)

Offline Doug

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Re: Douglas Aero 1937
« Reply #19 on: 07 Feb 2017 at 17:11 »
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.

http://www.douglasmotorcycles.net/index.php?topic=1102.msg3721#msg3721

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #20 on: 08 Feb 2017 at 20:02 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #21 on: 08 Feb 2017 at 22:56 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #22 on: 10 Feb 2017 at 19:21 »
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.
« Last Edit: 06 Mar 2017 at 12:17 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #23 on: 10 Feb 2017 at 21:02 »
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

Offline Ken Rogers

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Re: Douglas Aero 1937
« Reply #24 on: 12 Feb 2017 at 14:52 »
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 !

Offline polly

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Re: Douglas Aero 1937
« Reply #25 on: 12 Feb 2017 at 19:21 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #26 on: 12 Feb 2017 at 19:32 »
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.

Offline eddie

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Re: Douglas Aero 1937
« Reply #27 on: 12 Feb 2017 at 22:31 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #28 on: 14 Feb 2017 at 19:36 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #29 on: 14 Feb 2017 at 19:48 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #30 on: 16 Feb 2017 at 20:56 »
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?

Offline Doug

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Re: Douglas Aero 1937
« Reply #31 on: 17 Feb 2017 at 14:52 »
Yes. Same general design of nut, tab washer, taper, and two Woodruff keys.

-Doug

Offline eddie

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Re: Douglas Aero 1937
« Reply #32 on: 17 Feb 2017 at 15:02 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #33 on: 18 Feb 2017 at 12:33 »
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.
« Last Edit: 18 Feb 2017 at 19:55 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #34 on: 21 Feb 2017 at 12:39 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #35 on: 21 Feb 2017 at 17:30 »
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.



This illustration is for a 3-speed gearbox, but the 4-speed 'box should be the same design.

-Doug

Offline polly

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Re: Douglas Aero 1937
« Reply #36 on: 22 Feb 2017 at 16:46 »
the gearbox is filled with castrol spehrol, thats why there is a grease nipple on top!

Offline Eric S

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Re: Douglas Aero 1937
« Reply #37 on: 22 Feb 2017 at 17:25 »
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.
« Last Edit: 06 Mar 2017 at 12:24 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #38 on: 22 Feb 2017 at 17:39 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #39 on: 22 Feb 2017 at 19:43 »
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.
« Last Edit: 06 Mar 2017 at 12:24 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #40 on: 23 Feb 2017 at 11:05 »
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?

Offline Doug

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Re: Douglas Aero 1937
« Reply #41 on: 23 Feb 2017 at 19:04 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #42 on: 23 Feb 2017 at 19:50 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #43 on: 23 Feb 2017 at 20:17 »
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

Offline oily bloke

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Re: Douglas Aero 1937
« Reply #44 on: 24 Feb 2017 at 06:48 »
I use a syringe. A big one and inject it through the top.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #45 on: 25 Feb 2017 at 12:08 »
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??

Offline Eric S

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Re: Douglas Aero 1937
« Reply #46 on: 25 Feb 2017 at 17:50 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #47 on: 25 Feb 2017 at 18:55 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #48 on: 25 Feb 2017 at 20:03 »
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.
« Last Edit: 06 Mar 2017 at 12:27 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #49 on: 28 Feb 2017 at 16:44 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #50 on: 28 Feb 2017 at 19:15 »
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.





-Doug

Offline Doug

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Re: Douglas Aero 1937
« Reply #51 on: 28 Feb 2017 at 19:18 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #52 on: 28 Feb 2017 at 20:38 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #53 on: 28 Feb 2017 at 20:53 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #54 on: 28 Feb 2017 at 21:07 »
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?
« Last Edit: 28 Feb 2017 at 21:20 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #55 on: 28 Feb 2017 at 22:08 »
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.





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.



-Doug


Offline Eric S

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Re: Douglas Aero 1937
« Reply #56 on: 01 Mar 2017 at 20:30 »
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?
« Last Edit: 02 Mar 2017 at 07:59 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #57 on: 06 Mar 2017 at 12:43 »
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...

Offline cardan

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Re: Douglas Aero 1937
« Reply #58 on: 06 Mar 2017 at 21:06 »

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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Re: Douglas Aero 1937
« Reply #59 on: 06 Mar 2017 at 21:23 »
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.



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.



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.





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.



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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Re: Douglas Aero 1937
« Reply #60 on: 06 Mar 2017 at 21:27 »
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:
http://www.douglasmotorcycles.net/index.php?topic=2440.msg8835#msg8835

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #61 on: 10 Mar 2017 at 20:45 »
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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Re: Douglas Aero 1937
« Reply #62 on: 11 Mar 2017 at 03:42 »
Eric,

The petrol tank bolts are 17/64-25.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #63 on: 11 Mar 2017 at 18:10 »
Doug

I measured the 1/4-25 bolts and they are .232"
Seems a bit small for 1/4"?

Offline cardan

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Re: Douglas Aero 1937
« Reply #64 on: 11 Mar 2017 at 21:08 »

Since they're Allen heads, they might be M6 (6mm x 1mm pitch - 0.236 - 25.4 tpi)!

Leon

Offline Eric S

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Re: Douglas Aero 1937
« Reply #65 on: 12 Mar 2017 at 20:26 »
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


Offline Eric S

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Re: Douglas Aero 1937
« Reply #66 on: 13 Mar 2017 at 22:54 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #67 on: 15 Mar 2017 at 20:21 »
Does anybody have any idea regarding the clutch springs discussed just above?
Are they too strong?

Offline Doug

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Re: Douglas Aero 1937
« Reply #68 on: 15 Mar 2017 at 23:34 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #69 on: 16 Mar 2017 at 11:01 »
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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Re: Douglas Aero 1937
« Reply #70 on: 16 Mar 2017 at 11:03 »
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.

Offline Doug

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Re: Douglas Aero 1937
« Reply #71 on: 16 Mar 2017 at 15:10 »
Eric,

Quote
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


Offline Eric S

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Re: Douglas Aero 1937
« Reply #72 on: 16 Mar 2017 at 17:08 »
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...
« Last Edit: 16 Mar 2017 at 18:35 by Eric S »