Author Topic: Douglas Aero 1937  (Read 118220 times)

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Offline FN

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Re: Douglas Aero 1937
« Reply #400 on: 22 Jan 2021 at 18:24 »
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

Offline Doug

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Re: Douglas Aero 1937
« Reply #401 on: 22 Jan 2021 at 18:49 »
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

Offline FN

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Re: Douglas Aero 1937
« Reply #402 on: 22 Jan 2021 at 18:54 »
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

Offline Doug

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Re: Douglas Aero 1937
« Reply #403 on: 22 Jan 2021 at 19:23 »
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

Offline FN

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Re: Douglas Aero 1937
« Reply #404 on: 23 Jan 2021 at 16:00 »
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

Offline FN

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Re: Douglas Aero 1937
« Reply #405 on: 23 Jan 2021 at 17:25 »
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

Offline FN

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Re: Douglas Aero 1937
« Reply #406 on: 24 Jan 2021 at 18:08 »
Doug,
I have redone the tool for removing the ratchet. It is much stiffer and worked well.
Gerd

Offline Eric S

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Re: Douglas Aero 1937
« Reply #407 on: 01 Feb 2021 at 09:53 »
Hi Gerd
I am glad my miserable adventures are benefiting others enthusisats.
I haven't touched the engine since august as I am kind of disgusted because it tooks 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.

Offline FN

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Re: Douglas Aero 1937
« Reply #408 on: 07 Feb 2021 at 17:10 »
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

Offline eddie

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Re: Douglas Aero 1937
« Reply #409 on: 07 Feb 2021 at 18:57 »
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.

Offline FN

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Re: Douglas Aero 1937
« Reply #410 on: 08 Feb 2021 at 17:41 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #411 on: 09 Feb 2021 at 09:35 »
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 !

Offline Dave

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Re: Douglas Aero 1937
« Reply #412 on: 09 Feb 2021 at 20:29 »
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
This is what I use to check for all unread posts each day.

Dave

Offline Eric S

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Re: Douglas Aero 1937
« Reply #413 on: 10 Feb 2021 at 09:16 »
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...

Offline Dave

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Re: Douglas Aero 1937
« Reply #414 on: 10 Feb 2021 at 09:49 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #415 on: 08 Aug 2021 at 11:24 »
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.




[Attachments converted to linked images. 09Dec21 -Doug, Admin]
« Last Edit: 09 Dec 2021 at 05:25 by Doug »

Offline Doug

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Re: Douglas Aero 1937
« Reply #416 on: 08 Aug 2021 at 18:39 »
Looks like this.



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

Offline cardan

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Re: Douglas Aero 1937
« Reply #417 on: 09 Aug 2021 at 01:08 »
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

Offline eddie

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Re: Douglas Aero 1937
« Reply #418 on: 09 Aug 2021 at 07:36 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #419 on: 09 Aug 2021 at 10:26 »
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

Offline Aero

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Re: Douglas Aero 1937
« Reply #420 on: 09 Aug 2021 at 11:09 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #421 on: 28 Oct 2021 at 17:41 »
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?

Offline Eric S

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Re: Douglas Aero 1937
« Reply #422 on: 16 Dec 2021 at 17:48 »
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 !?


Offline Dads bike

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Re: Douglas Aero 1937
« Reply #423 on: 17 Dec 2021 at 14:08 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #424 on: 17 Dec 2021 at 15:55 »
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...

Offline Eric S

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Re: Douglas Aero 1937
« Reply #425 on: 28 Sep 2022 at 13:47 »
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.
« Last Edit: 28 Sep 2022 at 17:06 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #426 on: 04 Oct 2022 at 15:36 »
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?

Offline Eric S

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Re: Douglas Aero 1937
« Reply #427 on: 13 Oct 2022 at 17:13 »
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.

Offline cardan

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Re: Douglas Aero 1937
« Reply #428 on: 14 Oct 2022 at 00:07 »
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

Offline Doug

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Re: Douglas Aero 1937
« Reply #429 on: 14 Oct 2022 at 00:51 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #430 on: 14 Oct 2022 at 15:50 »
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.
« Last Edit: 14 Oct 2022 at 15:55 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #431 on: 14 Oct 2022 at 15:51 »
Last picture
Sorry they are all a bit big !

Offline cardan

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Re: Douglas Aero 1937
« Reply #432 on: 15 Oct 2022 at 04:39 »
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

Offline cardan

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Re: Douglas Aero 1937
« Reply #433 on: 15 Oct 2022 at 11:16 »
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

Offline Eric S

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Re: Douglas Aero 1937
« Reply #434 on: 15 Oct 2022 at 19:56 »
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
« Last Edit: 15 Oct 2022 at 20:05 by Eric S »

Offline cardan

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Re: Douglas Aero 1937
« Reply #435 on: 16 Oct 2022 at 02:20 »
Perfect, thanks. The magneto dates from June 1937, so presumably the bike was a late-season build.

Leon

Offline Eric S

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Re: Douglas Aero 1937
« Reply #436 on: 24 Oct 2022 at 12:42 »
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...?
« Last Edit: 26 Oct 2022 at 15:26 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #437 on: 28 Oct 2022 at 15:45 »
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 ???

Offline cardan

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Re: Douglas Aero 1937
« Reply #438 on: 29 Oct 2022 at 04:12 »
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

Offline eddie

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Re: Douglas Aero 1937
« Reply #439 on: 29 Oct 2022 at 09:05 »
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.

Offline cardan

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Re: Douglas Aero 1937
« Reply #440 on: 29 Oct 2022 at 09:25 »
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

Offline eddie

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Re: Douglas Aero 1937
« Reply #441 on: 29 Oct 2022 at 10:47 »
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.

Offline eddie

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Re: Douglas Aero 1937
« Reply #442 on: 29 Oct 2022 at 11:12 »
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!

Offline cardan

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Re: Douglas Aero 1937
« Reply #443 on: 29 Oct 2022 at 11:44 »
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


Offline Eric S

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Re: Douglas Aero 1937
« Reply #444 on: 29 Oct 2022 at 12:29 »
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.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #445 on: 01 Nov 2022 at 16:42 »
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?

Offline Doug

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Re: Douglas Aero 1937
« Reply #446 on: 01 Nov 2022 at 19:42 »
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

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

-Doug


[fix typo.  01Nov22 -Doug]
« Last Edit: 01 Nov 2022 at 20:44 by Doug »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #447 on: 01 Nov 2022 at 20:39 »
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!

Offline Eric S

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Re: Douglas Aero 1937
« Reply #448 on: 22 Nov 2022 at 10:19 »
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?



Offline Eric S

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Re: Douglas Aero 1937
« Reply #449 on: 22 Nov 2022 at 16:20 »
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?

 

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