Author Topic: Douglas Aero 1937  (Read 26126 times)

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Offline Eric S

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Re: Douglas Aero 1937
« Reply #100 on: 26 Feb 2018 at 17:29 »
Do you mean those rollers?
Are they pressed in?

Offline douglas1947

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Re: Douglas Aero 1937
« Reply #101 on: 26 Feb 2018 at 17:48 »
Yes Eric,
the studs for these rollers are pressed in.
A change is useful, if the rollers are not round anymore.
On your photo it looks not too bad.

Michael

Offline Eric S

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Re: Douglas Aero 1937
« Reply #102 on: 26 Feb 2018 at 19:27 »
Yes they look nice. They measure roughly .414"/10,5mm

But I don't think using larger ones for me would help because when I pre load the cable using the adjustment, I can make the clutch slip under the kick. Everything takes me back to a too short cable travel.

« Last Edit: 27 Feb 2018 at 08:28 by Eric S »

Offline douglas1947

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Re: Douglas Aero 1937
« Reply #103 on: 28 Feb 2018 at 15:15 »
The size of the rollers is okay (10,3mm).
The ring holding the rollers has several slots to fix it to the pin on the crankcase. Chose the best position for the longest way for the clutch operating arm (to have a long cable travel).
May be it is useful to use a spring to strech the cable?

Michael

Offline Eric S

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Re: Douglas Aero 1937
« Reply #104 on: 28 Feb 2018 at 17:15 »
Michael

yes there is 3 positions. But only 1 works, the one that makes the cam arm to the lowest position. Using other positions would raise the arm and the cable would be useless.
A spring is on the cable...


Offline Eric S

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Re: Douglas Aero 1937
« Reply #105 on: 05 Mar 2018 at 06:55 »
I have checked what should have been probably checked earlier, that is the roll bearings and it's not nice.
I noticed that the plate was not turning smoothly and for a cause.
Some of the "square rolls" are well used.
They slightly marked the inside of the "female" part.

The part where the ball bearings are is also marked (even broken) and even though the ball seems to be above the broken lips it may not help at all. Balls do not seem to be damaged though.
I am wondering if we can get larger size bearings so we can re-surface.
Can we get parts from the club? If so I would like to get a link as I don't seem to be able to find where I can go to get those.
Did those parts are heat treated and can be machined?
Anybody ever made new parts?

Offline Eric S

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Re: Douglas Aero 1937
« Reply #106 on: 08 Mar 2018 at 17:44 »
So nobody ever manufactured such parts?
I received an offer from a member for the bearings.
Before I can get them I need to know how we can "repair" the part or get it.

I see that I need to be a member of the Club to get parts from them. Anybody (club member) can tell me for now if these parts are available as I don't really planned to become a member for now...
Especially if they are not available from them.
« Last Edit: 28 May 2018 at 10:07 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #107 on: 08 Mar 2018 at 18:08 »
The clutch carrier sleeve is not available new, you have to find a second hand item or make it. I have made the entire flywheel and clutch, but changed the design of the bearing to ease manufacturing based on the tools I had at the time. Basically changed the two narrow groove for the rollers to one wide groove to take 1/8 needle rollers with a cage to keep them square. It was also the carrier sleeve for the thirties OHV models, which don't have the bearing balls; so not exactly the same as yours. It was written up years ago in the LDMCC's new ConRod magazine. Don't seem to have a photo on the computer, back in the film days.

It is also not uncommon to find the bore in the sprocket oval, or marked where the rollers chattered. If making a new carrier sleeve, you can make an adjustment on the diameter so you can lightly hone the sprocket true. This will help eliminate slop in the carrier sleeve bearing that contributes to clutch drag.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #108 on: 09 Mar 2018 at 08:22 »
Thank you Doug
I am going to investigate in 3D printing to get a new part made unles I found an amateur that can make a new one for a decent price...

Offline digcot65

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Re: Douglas Aero 1937
« Reply #109 on: 11 Mar 2018 at 10:51 »
Morning, was it the 250cc?I was in the middle of buying one from someone in the club who had a friend with one. Unfortunately, I even paid for the courier to collect the bike and the owner died suddenly the night before I was supposed to buy it.Some people said that the 250cc is underpowered, have you found this. Len

Offline Eric S

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Re: Douglas Aero 1937
« Reply #110 on: 12 Mar 2018 at 08:49 »
Len

Sorry I can't tell about the 250. Mine is a 600cc.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #111 on: 12 Mar 2018 at 19:08 »
So after some thinking, I am going to use some new 3/16x3/16 Roller bearings as the rest seems to be in good or usable order.
The grooves for the bearings are fine. The other side is marked but I will run with it.
This should tell me if the clutch now disengage well with the clutch not being drawn by the flywheel due to poor rollers.
If it does, it will be fine. Otherwise, it will be a mess as I have no clue where can be the problem.

If the roller bearings are worn out after a while, I will have the "other side" turned out, will install 5x5mm bearings and this should work.

In the meantime as the flywheel is on "average" condition, I would like to have it refinished.
I assume it was originally chromed as it is now. However the central "ring"of the external/visible side is painted.
Was it painted over the chrome? (I can't see how they would be able not to chrome the center of the wheel...



Offline Eric S

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Re: Douglas Aero 1937
« Reply #112 on: 15 Mar 2018 at 12:48 »
Well finally I will have a modern cage roll installed.
Using original 3/16 bearings on a marked and damaged outer part will leave damaged bearings in a short time.
So I am going to have this installed once for all...
I know it is not pure original system but I guess it made its time and I had no way to save it.

I did not get a reply re. this :
In the meantime as the flywheel is on "average" condition, I would like to have it refinished.
I assume it was originally chromed as it is now. However the central "ring"of the external/visible side is painted.
Was it painted over the chrome? (I can't see how they would be able not to chrome the center of the wheel...

Offline eddie

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Re: Douglas Aero 1937
« Reply #113 on: 15 Mar 2018 at 18:11 »
The flywheel would have been masked so that only the required areas were open to the plating process (much like you would mask up an item for painting, but using a material that forms an insulator against the electrical charge that is used to deposit the chrome plate).

  Eddie.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #114 on: 15 Mar 2018 at 19:12 »
Thank you Eddie
That makes sense. I did not know one could mask during plating ...

Offline Eric S

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Re: Douglas Aero 1937
« Reply #115 on: 26 Mar 2018 at 15:27 »
Hello friends
Finally I am having the clutch repaired with similar but larger (5x5mm) roll bearings. The modern cage was not suitable.

Anyone know the size of those 4 small screws that screws in the flywheel holding the little plate (that bears a notch to prevent the spring plate to turn)?
Seems to be 4mm(?) 25-TPi

Offline Doug

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Re: Douglas Aero 1937
« Reply #116 on: 26 Mar 2018 at 16:49 »
3/16-27 

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #117 on: 31 Mar 2018 at 15:03 »
Thank you Doug
Any idea where to source them? I would like to avoid hours filing to make them look a little bit better.

Offline Doug

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Re: Douglas Aero 1937
« Reply #118 on: 31 Mar 2018 at 15:58 »
Eric,

Well it is not a standard thread, as you probably realize. Have you checked with LDMCC spares?

I have made batches of other 3/16-27 threaded hardware on the CNC lathe, but not had the occasion to make that particular screw so do not have any in stock. Would be a bit of a challenge to get as close to the head as they did. I have another job in the lathe at the moment; after that I might try some experimentation. Most of this stuff I have been doing in 17-4PH stainless as it is easy to heat treat so that the slots and hexes don't burr over as easy.

-Doug

Offline ManfrerdSt

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Re: Douglas Aero 1937
« Reply #119 on: 31 Mar 2018 at 17:16 »
Eric,

what is that for a clutch lining?
looks like cork glued on?

Regards
     Manfred


Offline Eric S

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Re: Douglas Aero 1937
« Reply #120 on: 31 Mar 2018 at 18:00 »
Yes clutch lining is well cork glued in.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #121 on: 31 Mar 2018 at 18:01 »
Doug
I was pretty sure it was not standard even though "standard" seems to go a long way when you're talking about english screws.
And No I did not checked with LDMCC as I don't know where to go exactly and I don't have an adress for them.

I may save time, finally, straightening them with a file...

Offline Eric S

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Re: Douglas Aero 1937
« Reply #122 on: 09 Apr 2018 at 13:07 »
I need to open the gear box on my Aero as I need to check why the kick sometimes seems to miss a tooth.
Is there anything special I need to know beofre I open it?
Is there any risk of having everything fell off the gear box without a chance to find the right place for various parts when re-assembling?

Offline Doug

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Re: Douglas Aero 1937
« Reply #123 on: 09 Apr 2018 at 13:32 »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #124 on: 09 Apr 2018 at 17:00 »
Wonderful
Thank you one more time Doug
Do we need any gasket to re-assemble or shall we use a paste?

Offline Doug

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Re: Douglas Aero 1937
« Reply #125 on: 09 Apr 2018 at 18:11 »
Eric,

None of the ones I have taken apart (grand total of four) do I recall having gaskets. Nor does the 1936 Aero parts list mention any. So it looks like goo it is.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #126 on: 09 Apr 2018 at 19:13 »
Sorry Doug??
"So it looks like goo it is. "

Offline Doug

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Re: Douglas Aero 1937
« Reply #127 on: 09 Apr 2018 at 21:48 »
"goo" = paste, gasket cement. silicon sealant, Yamabond, Permatex, etc.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #128 on: 12 Apr 2018 at 17:10 »
Hello there

I am considering having this dynamo repaired.
Found a gentleman in UK that can do it for about 400
Add to this a repair I want to have made on the gear box to repair an epoxy, black patch that is plugging a hole on the top of the box and another 400.
On top of the repair for the gear box bearings and a mere 280
And a chroming of the flywheel and 110.
I am just wondering about the insanity of the whole affair.
Can I afford it ? Yes.
Does it make sense? I don't think so.

Not asking a question there, just putting some words together to launch a discussion among the pub/bar/tavern attendance...
« Last Edit: 28 May 2018 at 10:11 by Eric S »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #129 on: 07 May 2018 at 19:03 »
Hello

I see on my front wheel that the part below can be adjusted.
I am wondering how tight/loose I want it?

Eric

Offline Doug

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Re: Douglas Aero 1937
« Reply #130 on: 07 May 2018 at 20:34 »
Eric,

The usual setting for this type of taper roller bearing hub is so that there is the smallest perceptible lateral moment at the wheel rim/tyre.

Since the original taper roller bearings are obsolete and becoming more and more scarce, some of these hubs have been converted to radial ball bearings. Those should not have any pre-load, and ought to be re-engineered to have inner and outer distance sleeve of the same length.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #131 on: 28 May 2018 at 15:19 »
I was wondering if this light was correct for my 19367 Aero?
No I don't plan to change it anyway.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #132 on: 28 May 2018 at 15:20 »
I had my clutch back with the new bearings.
Flywheel is also back from chrome.
Center was painted black before chroming. Is that correct?
Also am I supposed to paint the inside although I don't see the need.
How was finished the back plate?

Offline Doug

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Re: Douglas Aero 1937
« Reply #133 on: 28 May 2018 at 17:19 »
The original headlamp would be Miller for 1936-38 Aeros. The shell you have looks like the Lucas wartime or postwar type.

The attached picture is the original Miller No. 74ES shell from my 1936 600cc Aero. Presumably they kept the same model for 1937-38. 



Flywheel. Center is painted black after chroming. I don't know if the factory masked the center during plating or not. Paint does not stick very well to chrome plating, but that might not have deterred them. Nowadays, the easiest solution is just to plate the entire flywheel. This avoids the expense of masking off portions, and avoids the accidental splattering of the mask on areas that you do want plated. Then mask off the areas to remain chrome and use a self-etching primer to get the paint to stick to the chrome. Mask and paint is cheaper than mask and plate. You might want to keep the self etching primer just a smidgen in from the radius of the rim, then overlap the black up the radius to the face of the rim. I find that this allows you to glide a razor blade over the chrome and around the rim to feather back the taped edge of the black paint without revealing primer underneath.



Inside the flywheel was not painted. Usually it has plating on it, but that was just incidental to the plating process as there was no reason to mask it off. Plating on the hub can mess up the fit of the carrier sleeve. Usually these are too loose and can benefit from building up, but the plating tends to be attracted to external corners and the end of the hub becomes larger than the middle. So the sleeve is tight to get on. Sometime the sleeve is mistakenly honed to get it onto the hub, only to find it as a rattle fit when in position.

What I have done is skimmed the hub and pressed on a bronze sleeve. This I turn to be a precise fit to the carrier sleeve. If the carrier sleeve is worn and needs a light hone, it allows the hub to be made oversized to suit. Eliminating any slop in the carrier sleeve and bearing will go a long way to eliminating clutch drag.

The backing plate is painted black. As far as I can tell the screws were a dull nickle plating, a standard rust proofing finish Douglas kept with into the Aero era, even when bigger items were a decorative chromium plating.

-Doug



[sketch added for flywheel painting. -Doug, 28May18]
« Last Edit: 17 Oct 2018 at 22:37 by Doug »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #134 on: 28 May 2018 at 17:51 »
Thank you Doug.
Much usefull as usual.
I talked to a painter and he said that Epoxy paint must be used on Chrome. And I have that on stock.
Hopefully I can do all that during this week.

Offline Doug

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Re: Douglas Aero 1937
« Reply #135 on: 28 May 2018 at 22:17 »
Flywheel painting sketch added to previous post.  -Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #136 on: 29 May 2018 at 06:00 »
Thank you Doug for the extra work detailing your explanation. It's perfectly clear now.

Offline Eric S

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Re: Douglas Aero 1937
« Reply #137 on: 29 May 2018 at 18:52 »
Made a nice masking with tape,using a rasor blade on my lathe to make a round template.
But I learned something today, you canot sand blast, even at a mere 2 bars or chrome may peel off nickel (I guess).
So flywheel is going back to chrome (he will redo it for me for free).

Question about the front brake. The part on mypart is not from Douglas. It is adapted from anter brand.
What color is the "brake" supposed to be? Right now it is bare alminium. Should I paint it black. What were the fashions back in the days?
« Last Edit: 07 Jul 2018 at 07:29 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #138 on: 30 May 2018 at 04:16 »
Drum, backing plate, and lever are black.

Sometimes you see restorations where the backing plates are left bare aluminum and the lever is plated, but period photos through the thirties show all-black was the standard finish.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #139 on: 30 May 2018 at 16:46 »
While preparing the flywheel for the new chrome, I thought that I may put in on my lathe to face it and remove some imperfections.
Starting at a low point where the pain may start I moved toward the center but by doing so I was removing more and more material until I stopped ending with a .3mm step.
it looks like the face is tapered with the center on same plane as the rim??

Now I am concerned about flywheel balancing or should I go ahead and remove this step?
« Last Edit: 30 May 2018 at 16:54 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #140 on: 30 May 2018 at 17:46 »
Eric,

Some flywheels, like that for the S6, are tapered between the rim and the hub. They start out from a recess of about a 1/32" below the rim surface and feather out to nil at the center where the clutch spring adjuster ring is. However the correct flywheel for the 600 Aero has the recess a constant depth. The rim is not the same level as the center, though. The recess is still a 1/32" below the face of the rim, but the center is 1/32" proud of the rim; so the step at the center of the recess is 1/16". The idea of the taper was to make the flywheel web thicker towards the center to better resist cracking. Later, perhaps they decided the added manufacturing complication of turning a taper was not worth the effort.

Given that your depth of cut increased towards the center, it sounds like you have a slightly earlier flywheel fitted. Function-wise, I think the whole unit is interchangeable. 

I don't turn the recess. The flywheel is too thin as it is. Since it will be painted anyway, any pitting or imperfections in the recess can be taken care of by the paint primer and filler. I have skimmed the rim, as filling pits on surfaces to be electroplated is a lot more difficult.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #141 on: 30 May 2018 at 19:01 »
Doug

Well it is too late now and the concern I have (you did not mentiond balance so it should not be an issue?) is that I have a small step just under the chrome plate (held with 3/16-27 screws) and I see no other way than going center down to erase this step. Step measured at .020"
Right now center remains .025" "proud of the rim"

You said it is too thin there so what shall I do?

Also what color for the 3/16-27 screws?

Offline Doug

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Re: Douglas Aero 1937
« Reply #142 on: 31 May 2018 at 03:45 »
Eric,

"Too thin" as in you don't want to make it any thinner. As you say, not anything that can practically be done about it now.

Does the step extend under the tin ring that traps the washer for the clutch springs? Basically, that is where the recess on the Aero flywheel ends. If so, leave as is. If it goes under the tin ring, well it is going to create a cosmetic gap that is awkward to fill.

Hopefully you had a slight tool nose radius when turning the recess to avoid creating a stress riser? All things being equal, if you had the flywheel running true in the lathe, what you machined off was an equal amount all the  way around and you should not need to re-balance the flywheel. It probably wouldn't hurt to check the balance, to see if it was in balance to begin with.

The tin ring and the plate for the clutch springs are painted black. Or, at least they are for 1936. I have seen others that were plated, but not sure if some models used a plated ring (the same part was used from 1930 to 38 on numerous models) or the plating was done post-factory. Only the flanged clutch adjuster nut is definitely plated.



The four 3/16-27 round head screws that secure the tin ring is a little tricky. Generally small hardware was nickel plated to give a durable, rust proof finish. I cannot see in period photos four bright dots suggesting they were left plated, but I have not come across any views that are one hundred percent conclusive. But it does look as if they were painted over. On my 1936 Aero, the screws were painted (exception to the general small hardware rule) and generally the finish on the bike as found indicates it was never altered. Whether these were things they changed on 1937-38 models to make an inexpensive model change, I don't know.

-Doug

Offline Eric S

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Re: Douglas Aero 1937
« Reply #143 on: 31 May 2018 at 07:03 »
Well I am going to try to make it nice and I will leave it this way.
Yes the step is right at the screw holes so I will have a small gap underneath the plate. It is barely visible but I like to make things nice (although I am limited by my hand's abilities).
You are right to point out the stress riser, I will make sure the step is well shaped.
The tin ring was chrome on my bike so I had it re-chromed.  I shoul live with it.
As for the screws, I have an hi tech silver "paint". Iw ill use it on the screws head. It will blend better with the chrome plate.
There again I should survive with the wrong color parts !

Doug I am really glad you are available. It makes research much easier, faster and accurate. If only my abaility to work was up to the task, I would be delighted...
Thank you !


Offline Eric S

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Re: Douglas Aero 1937
« Reply #144 on: 05 Aug 2018 at 11:02 »
Hello
It took me a while to work on my bike. In the meantime I had the flywheel chromed, painted and the rollers in the clutch pate replaced with larger 5mm rollers in an enlarged channel. Now the plates with rollers engages the flywheel quite tight (as it should be per the company that made the work)
I installed everything back in place.

Before
The Rear wheel at neutral on the stand was slightly turning and was easly stopped with 1 finger.
Engaging a gear made the box crack. When riding,engaging other gears was fine.

Now with new rollers.
The rear wheel is still turning but with more force. Engaging a gear is cracking a lot.
When pressing the clutch lever, I can not stop with the sole of my shoe the gear box sprocket and everything is turning at flywheel speed.
No way I can ride it now !

Clutch is disengaging for about 2mm when using the lever.

When flywheel is on the bench, launching the sprocket by hand, it goes 1/4 of a turn.
Why at neutral the gear box turns the wheel with engine running whereas when turning the sprocket by hand, at neutral, with no chain, the wheel do not moves?
Why the gear box at neutral turn the wheel with more force than it had with the old rollers?

Any help is welcome.
I am not yet quite fed up with it but getting close.

Eric
« Last Edit: 05 Aug 2018 at 14:18 by Eric S »

Offline Doug

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Re: Douglas Aero 1937
« Reply #145 on: 05 Aug 2018 at 23:12 »
Eric,

Sounds like the roller bearing is too tight. Unlike a typical cylindrical roller bearing, not only does it need to allow for free rotary movement, but it has to allow free axial moment as well so that the sleeve can move sideways inside the sprocket and lift the pressure plate. Or to put it another way, so the sprocket (and integral clutch disk) can float along the outside of the rollers. It is a bit of a balancing act, as any additional clearance exacerbates the problem of the clutch plate tipping (under the pull of the chain) and the periphery dragging on the pressure or backing plate. It the bearing does not have to be so loose that it drops through while static; it will be rotating at the time. But it does need to be free enough that it can float along the shaft and find a point midway between the pressure plate and the backing plate where - hopefully - it is not touching either! Velocettes are not the only marque with a fickle clutch... As mentioned the hub sleeve and the sprocket bore can be out of round. This makes it difficult to obtain the right running clearance as by the time you get rid of all the tight spots the bearing is now excessively loose everywhere else. If you have tight spots, or the roller bearing is just fitted too tight in general, you will likely also have a problem where any minute variations will cause the assembly to 'screw' the clutch disk one way or the other. That will keep the clutch disk up against either the pressure plate or the backing plate with a few pounds of force, keeping it from disengaging completely.

Also, remember the hub or carrier sleeve needs to slide along the flywheel hub freely (usually the clutch springs and your grip on the clutch lever provide enough impetus), without contributing any more clearance (allowing the sleeve and the sprocket/clutch disk to tilt) than humanly possible. The total lift of the pressure plate free of the clutch disk is limited. So if the disk or the bearing and sleeve it rides upon were to tilt, the rim of the clutch disk can still be in contact with the driven, rotating parts of the flywheel.

However it does sound from your description like the roller bearing is too tight a fit and when the clutch is released it cannot 'float' and find a happy medium clear and free between the pressure and backing plates. Indeed, the very tightness may be driving it up against one or the other. Especially your description of giving the sprocket a twirl on the bench, and it only going a part turn before encountering resistance. If you turn it the other way, does it immediately free off like the clutch disk is screwing away from contact? Can you (partially disassembled on the bench) spin the sleeve inside the sprocket without it threading itself through the sprocket?

-Doug

[Edit, the Aero clutch is single sided and does not have the pressure plate utilized on the big ohv twins. Since the term pressure plate is referenced in subsequent posts and has caused confusion, it is struck out rather than deleted.  07Aug18 -Doug]
« Last Edit: 07 Aug 2018 at 18:23 by Doug »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #146 on: 07 Aug 2018 at 17:27 »
Doug
I guess I can see what you mean, barely (lacking again some terminology)...

I check some clearance;
The total movement of the disk in the Flywheel measured from the spring holes with flywheel on the bench (TOTAL movement) is .130"/3,3mm
The movement of the came ring from the lever/cable is .083"/2,10mm
The movement of the disk installed in the flywheel as installed and pushed by the lever/cable/cam is .080"/2,0mm

Just to make sure that this is enough.

Now the interesting thing.
When installed, no chain, I can run the sprocket with fingers and it turns freely, can make it +/-1 turn with 1 knock of the fingers. (The other day I said it was not really turning but I guess it was dragging against the pressure plate. Anyway today it turns "good")

Now If I install 2 springs with the nut barely 1 turn, the sprocket do not turn anymore when pushed with fingers. And if I turn the flywheel by hand, I can barely stop the sprocket with 1 finger.

The only think I can see is that the lip of part #13 pushes against pressure plate #6
Any other idea welcome.


Offline Doug

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Re: Douglas Aero 1937
« Reply #147 on: 07 Aug 2018 at 18:16 »
Eric,

Oops, I owe you an apology as I forgot the Aero clutch does not have the pressure plate like the big, ohv machines did. So my using the term pressure plate probably muddied the waters. I will strike that out in the previous reply.

The main thing, still, is to check that the bearing is not too tight. If without any springs installed the sprocket can be given a twirl with you fingers and it rotates freely and does not drag to a halt after a turn or two, then that sound fine. Once you start installing springs, I would expect the sprocket to start to offer resistance. Unless you pull the clutch lever, then it should again spin freely!

Referring to your illustration for item numbers: In normal operation, the clutch springs [2] press on the flange of the carrier/hub sleeve [13]. This applies pressure via the ball bearings [8] to the clutch plate [6] and forces it against the backing plate [12] to provide drive. The sprocket is along for the ride. Roller bearings [7] stabilize the sprocket and take the chain load. The bearings only come into play when the clutch plate is lifted, and allow the clutch disk and sprocket to rotate independently, and freely one hopes, from the flywheel.

When you operate the clutch lever, it uses the thrust ball race [5] to shove the whole sprocket and clutch assembly [6, 7, 8, 11, 13] sideways against the pressure of the clutch springs. Once the clutch disk is clear of the backing plate, it should be free. In the case of the Aero, there is no pressure plate occupying the void between the clutch disk and the inside face of the flywheel. This was used on the higher power machines to provide more capacity, the clutch disk had friction material on both side. So lacking the pressure plate, one does not have the problem of running out of space the lift the clutch disk. In theory if the lift were enough the back side of the clutch disk (the side not used for providing drive) could rub or drag on the inside of the flywheel. But I don't think one has enough clutch lever travel for that to ever be a problem. Also I would expect an metallic rubbing sound of aluminum on steel.

When you upgraded from 3/16 to 5mm rollers and enlarged the width of the grooves, how precise were the grooves cut?. Since the rollers do not have a cage, they rely on a nice fit in the grooves to keep them square to the race. It is not enough that they are crowded in there to keep them square.

As far as setting the clutch, you want the minimum amount of slack in the clutch cable so that you have maximum lift. I usually check it right where the clutch cable attaches to the clutch operation arm, behind the flywheel. So long as it can be wiggled in rotation just a smidgen, that is enough slack. Don't expect the thrust bearing [5] to ever stop spinning. It is enough to make sure the pressure is off it, having it idle along due to parasitic drag is unavoidable. Since the clearance is set to a minimum, you do have to check it often to make sure wear of the clutch disk has not allowed it to settle down on the thrust bearing and so bear the load; preventing the disk from bearing against the backing plate.

If the bearing balls [8] and their races are o.k., the flange on the carrier sleeve [13] should not come anywhere close to the clutch disk. It should never rub on it, or the grease slinger [11]. If the rivets for the clutch disk have been replaced by bolts or screws, you have to make sure they clear that flange as well.

-Doug

« Last Edit: 07 Aug 2018 at 19:19 by Doug »

Offline Eric S

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Re: Douglas Aero 1937
« Reply #148 on: 07 Aug 2018 at 19:10 »
Doug
It's much easier for me with numbers !

Once you start installing springs, I would expect the sprocket to start to offer resistance. Unless you pull the clutch lever, then it should again spin freely!
Not really. When lever pulled, the resistance is less but I can barely turn the disk with  finger.

I had the rollers' groove re-cut by a company that makes bearings; I assume they know what they are doing...

I have to open it to find some marks on the metal... I am becoming rather good at it.

Offline eddie

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Re: Douglas Aero 1937
« Reply #149 on: 07 Aug 2018 at 19:21 »
Doug,
         Looking at the illustration that Eric posted, it appears that that clutch would never work properly. The release bearing pushes against the face of the sprocket to lift the cork plate away from the pressure plate. That is OK but the thrust is being taken through the sprocket/clutch plate assembly and it's thrust bearing to lift the carrier sleeve against the spring pressure. That will always result in the flywheel/carrier sleeve/ clutch plate wanting to rotate as a unit instead of allowing the plate to spin free. Now, if the carrier sleeve was shortened to be just proud of the face of the sprocket, the release bearing could then have a reduced inside diameter so that it lifted the carrier sleeve, thus leaving the clutch plate free to turn independent of the flywheel.

   Does that make sense??

   Regards,
                 Eddie.

 

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