Author Topic: Douglas Aero 1937 (Read 118232 times)

Eric S · « **Reply #300 on:** 11 Dec 2019 at 13:38 »

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??

Aero · « **Reply #301 on:** 11 Dec 2019 at 17:28 »

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.

Eric S · « **Reply #302 on:** 13 Dec 2019 at 08:26 »

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

Eric S · « **Reply #303 on:** 18 Dec 2019 at 20:08 »

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)

[Attachments converted to linked images. 08Dec21 -Doug, Admin]

Eric S · « **Reply #304 on:** 29 Dec 2019 at 16:01 »

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.

[Attachments converted to linked images. 08Dec21 -Doug, Admin]

Aero · « **Reply #305 on:** 29 Dec 2019 at 20:56 »

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

Doug · « **Reply #306 on:** 30 Dec 2019 at 03:52 »

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

Eric S · « **Reply #307 on:** 30 Dec 2019 at 10:04 »

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...

Eric S · « **Reply #308 on:** 30 Dec 2019 at 16:20 »

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)

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Aero · « **Reply #309 on:** 30 Dec 2019 at 17:42 »

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

Eric S · « **Reply #310 on:** 30 Dec 2019 at 19:29 »

Too late !
Did not tried to twist it over, just checked for hardness but have not seen a spring...

Eric S · « **Reply #311 on:** 31 Dec 2019 at 11:00 »

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

Eric S · « **Reply #312 on:** 05 Jan 2020 at 10:54 »

Am I well reading 6Q/237?
Is that inline with what one shall expect there?

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Doug · « **Reply #313 on:** 05 Jan 2020 at 17:39 »

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

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]

Eric S · « **Reply #314 on:** 06 Jan 2020 at 09:41 »

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€/135£/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 !?

Aero · « **Reply #315 on:** 06 Jan 2020 at 10:04 »

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.

Eric S · « **Reply #316 on:** 06 Jan 2020 at 12:21 »

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.

Aero · « **Reply #317 on:** 06 Jan 2020 at 13:07 »

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?

eddie · « **Reply #318 on:** 06 Jan 2020 at 14:32 »

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.

Eric S · « **Reply #319 on:** 06 Jan 2020 at 17:36 »

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...

Eric S · « **Reply #320 on:** 09 Jan 2020 at 08:34 »

The cover on the tool box on my bike is correct but has been repaired.
Was it stamped steel or aluminium cast originally?

Doug · « **Reply #321 on:** 09 Jan 2020 at 17:14 »

Cast aluminium.

Eric S · « **Reply #322 on:** 15 Jan 2020 at 18:27 »

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.

[Attachments converted to linked images. 08Dec21 -Doug, Admin]

Doug · « **Reply #323 on:** 15 Jan 2020 at 20:50 »

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!

-Doug

Eric S · « **Reply #324 on:** 16 Jan 2020 at 10:06 »

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.

eddie · « **Reply #325 on:** 16 Jan 2020 at 12:37 »

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.

Eric S · « **Reply #326 on:** 22 Jan 2020 at 14:22 »

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

Doug · « **Reply #327 on:** 22 Jan 2020 at 15:33 »

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

Eric S · « **Reply #328 on:** 22 Jan 2020 at 16:19 »

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...

Aero · « **Reply #329 on:** 22 Jan 2020 at 18:03 »

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

Eric S · « **Reply #330 on:** 23 Jan 2020 at 08:37 »

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.

Eric S · « **Reply #331 on:** 24 Feb 2020 at 17:52 »

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.

[Attachments converted to linked images. 09Dec21 -Doug, Admin]

Eric S · « **Reply #332 on:** 27 Feb 2020 at 17:00 »

Any help there?

Eric S · « **Reply #333 on:** 04 Mar 2020 at 19:29 »

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...

Eric S · « **Reply #334 on:** 16 Mar 2020 at 16:01 »

Do we have any advice NOT to use 1mm thick paper gasket between both engine blocks? Is that too thick?

eddie · « **Reply #335 on:** 16 Mar 2020 at 17:28 »

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.

Eric S · « **Reply #336 on:** 16 Mar 2020 at 18:59 »

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)

Eric S · « **Reply #337 on:** 20 Mar 2020 at 17:43 »

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...

Aero · « **Reply #338 on:** 20 Mar 2020 at 22:36 »

Sounds good.
Looking forward to hearing that it is up & running again

Eric S · « **Reply #339 on:** 23 Mar 2020 at 23:31 »

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...

[Attachments converted to linked images. 09Dec21 -Doug, Admin]

Aero · « **Reply #340 on:** 23 Mar 2020 at 23:58 »

Your pic is correct. The ring with the slots fits in the piston groove with the oil return holes.

Eric S · « **Reply #341 on:** 25 Mar 2020 at 20:38 »

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?

Doug · « **Reply #342 on:** 25 Mar 2020 at 20:45 »

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

Eric S · « **Reply #343 on:** 26 Mar 2020 at 12:12 »

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

[Attachments converted to linked images. 09Dec21 -Doug, Admin]

Aero · « **Reply #344 on:** 26 Mar 2020 at 12:50 »

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

Eric S · « **Reply #345 on:** 26 Mar 2020 at 13:03 »

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?

Aero · « **Reply #346 on:** 26 Mar 2020 at 14:25 »

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.

Doug · « **Reply #347 on:** 26 Mar 2020 at 17:51 »

Quote

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]

Eric S · « **Reply #348 on:** 26 Mar 2020 at 18:16 »

Doug
Thank you for those explanation.
So I understand that the standard configuration (plain-plain-hollowed and plain on skirt) is required.

Eric S · « **Reply #349 on:** 04 Apr 2020 at 17:15 »

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?

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