C: Clutch Refreshing Vincent Twin Clutch seals and pieces

Peter Holmes

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Notice how I said, unless it has one of the dowty type spacers, I will refit what came out to retain the correct distance for the nut verses C 17 bush clearance plus a shim as necessary. The point was to prevent an oil leak from this area, and that is generally how I do it, nothing special but it seems to work.
Understood now, so when a Dowty seal fails you retain the metal ring and replace the damaged or missing rubber seal with Threebond, sounds perfect to me, what threw me a little was when you referred to the flat surface of the C3 carrier.
 

craig

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so to modify the inboard end of the C3 clutch shoe carrier, you can simply use a valve grinding stone to angle cut a bevel to allow a simple 022 oring to fit up against the spacer ?
C3 up against PD21.
Is 30 degrees the best angle?

where do you find a valve stone with shaft for home use?
i can supply a drill press with holding vise,



30DegreeStonePic2.jpg
 
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BigEd

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so to modify the inboard end of the C3 clutch shoe carrier, you can simply use a valve grinding stone to angle cut a bevel to allow a simple 022 oring to fit up against the spacer ?
Is 30 degrees the best angle?

where do you find a valve stone with shaft for home use?
i can supply a drill press with holding vise,



View attachment 25387
I don't think the angle is important as long as the "O" ring protrudes a little from the end of the "C3" so that it is compressed when everything is tightened up.
 

timetraveller

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Big Ed is right but I used the back side of the grind stone which was at 45 deg, not 30 deg. I bought these stones decades ago and they came as standard with 30 deg on one side and 45 on the other. If you have access to someone who is a good machinist then I would get them to machine a proper recess inside the end of the tube part of the C3. I used the grind stone dodge because my lathe's four jaw chuck would not take the diameter of the large side of the C3. I do not want to 'go on' about this mod as everyone has their own way of doing things but it really is easy, totally effective and stops oil getting into the splines rather than trying to stop it getting out at the other end.
 

craig

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I have now in hand what appears to be the correct parts to convert my C20, C3, G3 early configuration to C20/1, C3/2, G3/1 allowing the use of a simple o-ring to provide the seal at the clutch nut.
I made up a simple drawing to illustrate this change..............and now I have some questions about this "late model" up grade. The dark green G3mod threads on to a G3 to convert to G3/1.

ClutchNutC20_1LargeTV.jpg


1) This new configuration calls for a shortened C20/1 nut that gives up the indexing feature of the old style C20 and simply tightens up against a new C3/2 that provides just a flat surface.
C3/2 does not fit tight on the shaft, neither did the C3.....isn't this indexing early feature a better mechanical design?

2) Physically, upon assembling the pieces, there appears to be enough room at the C18/2 o-ring slot to allow 2 o-rings stacked in the slot . Is this the case with other installations?

3) Is this drawing accurately depicting the configuration? I know the drawing is not to scale.

Thanks for any help on this.
Cheers
Craig
 
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timetraveller

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As an astronomer and not an engineer I might be missing some important point here but why would you choose to do all this when a simple modification to the rear of the shoe carrier tube can completely cure any oil ingress. It works with either the early or later type of gearbox main shaft etc. If there is a good reason then let us know as I do not want to be advising people to do something which is prejudicial to the longevity of their bikes.
 

BigEd

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As an astronomer and not an engineer I might be missing some important point here but why would you choose to do all this when a simple modification to the rear of the shoe carrier tube can completely cure any oil ingress. It works with either the early or later type of gearbox main shaft etc. If there is a good reason then let us know as I do not want to be advising people to do something which is prejudicial to the longevity of their bikes.
I was thinking the same thing.:confused:
 

craig

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As an astronomer and not an engineer I might be missing some important point here but why would you choose to do all this when a simple modification to the rear of the shoe carrier tube can completely cure any oil ingress. It works with either the early or later type of gearbox main shaft etc. If there is a good reason then let us know as I do not want to be advising people to do something which is prejudicial to the longevity of their bikes.

Great C3/PD21 o-ring seal solution, thank you, but I want to know the details of the old/new C20, C3, G3 pieces.

I am looking at the "new" pieces and wondering why? no indexing? loose o-ring?
As an engineer I need to know all the details where possible, then make a decision.
In this clutch shaft case I can see multiple seals applied.

I don't understand why the C20/C3 indexing is lost and C3/2 allowed to wobble on the G3/1.
This is not a issue?, never been an issue? 2 million miles on a D with no clutch leaks?

I understand that C20 nut comes loose as standard fare?
Have I seen instructions to leave C20 nut loose to allow no binding in the clutch action?
Why is the groove to take the new C18/2 o-ring seal deep enough to take two o-rings?
Does the alloy spacer in use with a C18/3 crush down allowing loose C20/C3 interface?
Do you over torque a C20 nut to allow the spring lock, or do you back off the C20 torque?
Is there a torque spec for C20 nut beyond KTB?

Cheers
Craig
 
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