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C: Clutch Twin clutch . centralizing plunger.

john998

Well Known and Active Website User
VOC Member
In a drawing of the twin clutch posted on this forum it appears that the centralizing plungers C11/1 are shown in contact with the both C14 pins. Is this correct?
In my experience there is always some clearance that allows C13 a few degrees of rotation either way before any contact.
John Stainton.
 

stu spalding

Well Known and Active Website User
VOC Member
Hi John, the plungers should be just touching the pins. If the pins are worn they can be swapped around in the plate carrier C13. If you've still got clearance the collar on the end of the plunger can be undercut providing the plunger isn't hardened. (some are). Cheers, Stu.
 

stu spalding

Well Known and Active Website User
VOC Member
An alternative idea on why the primary plates C21 & C23 are slightly dished is that they flatten under spring pressure and thus do not need to be ground flat, in fact this may even be detrimental. None of the clutches that I've rebuilt have required this step and have worked fine. Cheers, Stu.
 

john998

Well Known and Active Website User
VOC Member
In 55 years of Vincent clutches (50 heaven, 5 years hell) the problem has never been the primary clutch. The servo clutch has worked for me for touring, road racing, hill climbing and sprinting and pulling side cars on occasions with a trailer.
As far as I can remember all the ones I have worked on had several degrees of movement between the plungers C11/1 and the pin C14. On looking through my used clutch bits I found one C11 that was a tenth of an inch longer than all the others. Have made up some of this length plungers that now are in contact with C14.
As soon as the weather improves I will find out if this is an improvement.
Having said all that if you clutch is working reasonably don't fiddle with it they seem to take a long time to settle back in. John
 

Cyborg

Well Known and Active Website User
VOC Member
An alternative idea on why the primary plates C21 & C23 are slightly dished is that they flatten under spring pressure and thus do not need to be ground flat, in fact this may even be detrimental. None of the clutches that I've rebuilt have required this step and have worked fine. Cheers, Stu.
I’m just in the middle of sorting out all the pieces to assemble a clutch. The C23 is very slightly dished and don’t really see that being an issue. In the long run, I’m not sure how much taper would be taken up by the springs (but just guessing). I figure the C24 friction plate would eventually just bed in to the taper. At this point I have only eyeballed it with a straight edge, but the taper doesn’t seem to be consistent all the way around which could be a problem. Will have a better idea once it’s checked with a dial indicator. What is a problem.... I chucked the C21 in the lathe just to clean the crud off and noticed it has way too much runout. Didn’t bother measuring it... just tossed it in the yard art bin.

John. I had added C11/1 to the list of things to buy. For some reason it never dawned on me to make them. What material did you use? Thinking I could use stainless because that’s what I have on hand?? Any advice would be appreciated.

Did I read somewhere about leaving the PD27 springs out and just using the OP11?

Now I’ll go search for that clutch drawing.
 

Cyborg

Well Known and Active Website User
VOC Member
Thanks Stu,
I had a look on the spares site, but don’t see them listed. Do you have Derek Sayer’s contact info? Although.... it would be nice to be able to get them from the spares co though. Have to order some stuff from there anyway.

While I’m here... what was the reason that they changed the shape of the C10 toggles. The new ones have a square end. Was that just to simplify manufacturing? Is there a reason I shouldn’t use these. I picked out the best two.
3EF49014-737C-4492-8CDF-5D810DD82454.jpeg
 

Cyborg

Well Known and Active Website User
VOC Member
Ps... I couldn’t find that clutch diagram that John referenced in his first post.... so if anyone can point me in the right direction.

When looking I found a post from you Bill. Going to take that warped C21 out of the bin and make a clutch holder out of it. Good idea... thanks.
 

Bobv07662

Well Known and Active Website User
VOC Member
I reported on a similar issue with my twin clutch...C11/1, C14 clearance. Rather than turn up longer plungers I made two bushings to fit over the C14 pins, great result! Combined with matching springs and cups to get a level primary clutch lift I now have a smooth engagement with the abrupt take up eliminated.
 

Bill Thomas

Well Known and Active Website User
VOC Member
I still run a pair of Lightened Drums !, I do worry they will go bang !,
But Mad Max thought they were OK ?.

For me getting NO play on the plungers was a good move,
Or the shoes can flap about and catch the drums a bit ?.
But my Special has a bent main shaft, Because of 10 years of Sprinting and a gearbox lockup !,
So that will never be perfect.

The best thing for getting into gear I think is get the tick over low ?,
But again with Big Carb's and Mk2 Cams not so easy for me.

And if ever your chainwheel is off, Change the oil seal between the bushes, They go hard after being laid up
And once oil is on the shoes you are Stuffed !.
 

stu spalding

Well Known and Active Website User
VOC Member
Hi Cy, I hope Derek doesn't mind me putting his number online, ************** . I've no idea about the toggles.

Hi Bill, I've mentioned it before but it is sometimes possible to get the shoe carrier C3 to run true by moving it round on the shaft, spline at once, and checking, with the nut tight. There is occasionally a machining error in C3 which cancels out a bit of bend in the shaft. Cheers, Stu.
 
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Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
I recall many years ago the toggles (C10) could be made shorter so giving more pressure onto the drum, the same effect would be with worn shoes, as for the seal between the two bushes could be removed if an "O" ring of a certain size was fitted to the main shaft and a taper (sham-fer) behind the shoe carrier.
bananaman.
 

Cyborg

Well Known and Active Website User
VOC Member
Hi Cy, I hope Derek doesn't mind me putting his number online, **************. I've no idea about the toggles.

Hi Bill, I've mentioned it before but it is sometimes possible to get the shoe carrier C3 to run true by moving it round on the shaft, spline at once, and checking, with the nut tight. There is occasionally a machining error in C3 which cancels out a bit of bend in the shaft. Cheers, Stu.
And then you can try to get a C20 to run in harmony with the C3.
I am fortunate in that there was a NOS mainshaft hiding under the bench. I didn’t realize it at first because it was covered in a very thin layer of a very hard black unknown substance. It took a bit of work to remove it from the threads so the C20 would thread on. Petrified cosmoline?
Almost tempted to turn the C20 while it is on the shaft, sleeve it and then turn it back down to size..... speaking of centralizing things.
 
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