C: Clutch Twin Clutch Drag

[Bill Thomas]

Mine was Just a quick bodge to take up the slack,
My shoes were just flapping, Only a few thou, But the plungers should be touching,
Can't see how pulling the lever would do anything ?,
Strange one that ?,
But the whole clutch is strange !, But I like it,

I remember going to a rally in the midlands, I had just stopped racing , So maybe 1987 ish,
And the NEW thing was the multi plate, Everybody was going that way,
And I was looking for old stuff !, They thought I was MAD !,
Don Alexander and Marion were there and Don was helping me find the best of a bad bunch !,
I had been using an old Norton clutch for racing.

Another thing is Primary Chain tension, If the chain is too tight, That can upset the clutch,
And the chain gets tighter as the bike gets hot.

 

[greg brillus]

Peter how much end float does your C13 assembly have with the C 20 nut done up tight.......?

 

[paw99]

C13 end float adjusted for minimum while free to rotate, probably about 10 thou. But will try looser next test.

 

[paw99]

Mine was Just a quick bodge to take up the slack,
My shoes were just flapping, Only a few thou, But the plungers should be touching,
Can't see how pulling the lever would do anything ?,
Strange one that ?,
But the whole clutch is strange !, But I like it,

I remember going to a rally in the midlands, I had just stopped racing , So maybe 1987 ish,
And the NEW thing was the multi plate, Everybody was going that way,
And I was looking for old stuff !, They thought I was MAD !,
Don Alexander and Marion were there and Don was helping me find the best of a bad bunch !,
I had been using an old Norton clutch for racing.

Another thing is Primary Chain tension, If the chain is too tight, That can upset the clutch,
And the chain gets tighter as the bike gets hot.

Regarding end force, after concluding pilot clutch was not the problem I tried to repeat problem with pilot plates removed so I could watch shoes. Will post video in a minute I hope. I made a dummy outer plate from sheet steel (grey in video), and spaced it with washers and nuts. In video my black hand rotates the grey plate (simulated drive) and shoes can be seen to engage/centralise lovely.
Then I rotate the grey plate to engage shoes and pull in clutch, now shoes do not centralise until I let go clutch lever. The only thing the clutch lever does with this setup is to push grey plate, which pulls C13 outward. I then saw marks on the sides of plunger housing 'noses' and corresponding (but much fainter as steel) marks on inside of back C13 disc.
Back to video.. every time the shoes stay engaged is because my other hand is holding clutch lever in. Sorry can't show both hands. Thanks to Stu Spalding for his dummy clutch centre giving me this idea.

 

[paw99]

Regarding end force, after concluding pilot clutch was not the problem I tried to repeat problem with pilot plates removed so I could watch shoes. Will post video in a minute I hope. I made a dummy outer plate from sheet steel (grey in video), and spaced it with washers and nuts. In video my black hand rotates the grey plate (simulated drive) and shoes can be seen to engage/centralise lovely.
Then I rotate the grey plate to engage shoes and pull in clutch, now shoes do not centralise until I let go clutch lever. The only thing the clutch lever does with this setup is to push grey plate, which pulls C13 outward. I then saw marks on the sides of plunger housing 'noses' and corresponding (but much fainter as steel) marks on inside of back C13 disc.
Back to video.. every time the shoes stay engaged is because my other hand is holding clutch lever in. Sorry can't show both hands. Thanks to Stu Spalding for his dummy clutch centre giving me this idea.

And here is link to video

Cheers
Peter

 

[Bill Thomas]

The first one worked for me , Very clever , Well done,
I still don't know why ,
Move over let me have a look .

 

[paw99]

The first one worked for me , Very clever , Well done,
I still don't know why ,
Move over let me have a look .

And now I assembled clutch (again...), This time with bushed pivot holes in shoes, and more end play on plungers and more end float on C13. And the drag after drive is better! Another two items for the list of causes of this problem, too tight clutch adjustment and too floppy shoes. I still expect all these are made worse by my clutch shaft runout, but it looks like ready for the first road test in months.
But not on such a windy day!
A huge thanks to all advisers on forum.
Cheers
Peter

 

[paw99]

And now I assembled clutch (again...), This time with bushed pivot holes in shoes, and more end play on plungers and more end float on C13. And the drag after drive is better! Another two items for the list of causes of this problem, too tight clutch adjustment and too floppy shoes. I still expect all these are made worse by my clutch shaft runout, but it looks like ready for the first road test in months.
But not on such a windy day!
A huge thanks to all advisers on forum.
Cheers
Peter

And now, so much later, I think my clutch is sorted. Having started by replacing oil seals and bushes (several) that may have worsened the drag or failure to centralise by reducing free play, and most clutch components now new. Yes there needs to be free play, not least to tolerate any runout. Thanks to everyone, especially to Marcus for lending me mainshaft to test theory. All my fiddling leaves me still convinced that clutch shaft runout only became a problem when clutch lever pulled and wedged close tolerances together. Now new shaft and a bit more end float on C20 nut gives workable clutch. And the bonus is I filed kickstart quadrant ti prevent jamming (worked fine) and new selectir pawl spring (more defined gear selection and no jumping out). So a long time, but three fixes, great and thanks to all. Now my count of possible clutch drag causes is up from 12 to 13.
Next target 276 carburation!

 

[Gene Nehring]

Having just spent a couple weekends working out some issues with my Vincent clutch my thoughts are this.

As Greg has mentioned primary chain tension needs to be right. Mine was a bit tight according to David who came to help me.

The cups should be even in height and flat against the outer plate. The springs should all be the same length. The clutch plate should be lifting evenly / square.

The clutch cable should have a smooth run and be easy to lift. May pay to check the centres of the levers you’re using.

I used the Roy Cross jig I made years ago to set the spring tension of the clutch shoes and this is often over looked. Along with this the correct amount of chamfer on the shoes is also important. Again not too tight.

Anyways just some thoughts. Good luck with it.

 

[greg brillus]

Just getting back to the stock vin clutch........Any thoughts on harshness or savage take off.......this after a clutch rebuild........everything in top order, end floats and clearances all good........Is it possible that having too much clearance between the linings and the drum diameter could cause this........especially if the lining material is the modern soft stuff........I was thinking along the lines of early rear drum brake cars, where when the linings are worn, the rear brakes seam very savage, probably due to the self energising affect being made worse because the lining/drum clearance is a bit too much........I know badly worn/broken plunger springs will do this, but all of these and the pin end floats are all fine on this clutch assembly........I know someone who changed the linings to a harder material and this solved their clutch snatching........but i'm thinking that too much drum/lining clearance might be the issue.........What say you........Cheers......Greg.