C: Clutch Twin Clutch "balance "

[Bill Thomas]

I was using Search, Could not find what I wanted, But found this on clutch balance, I think T.T. asked about a bit on this ?.
" Mercurycrest ", 26/8/14 ," On my race bike I ended up drilling holes in the heavy end, ( Balance them on the pivot hole ) Of the shoes and adding lead to the light ends, So it would shift at 7K.
I learned about this from Bob Kounts, I am sure Rollie Free told Bob about it and PCV more than likely told Rollie."
Cheers Bill.

 

[stu spalding]

I was using Search, Could not find what I wanted, But found this on clutch balance, I think T.T. asked about a bit on this ?.
" Mercurycrest ", 26/8/14 ," On my race bike I ended up drilling holes in the heavy end, ( Balance them on the pivot hole ) Of the shoes and adding lead to the light ends, So it would shift at 7K.
I learned about this from Bob Kounts, I am sure Rollie Free told Bob about it and PCV more than likely told Rollie."
Cheers Bill.

Hi Bill, there is an article in "Ten Years On" p173 from MPH 597 by J. Bickerstaff, about the clutch balancing efforts of Paul Zell and Dan Smith. I have looked at this and I feel that the removal of metal alone is insufficient to achieve balance without weakening the shoe and Paul Zell's addition of weights is needed. Just before my prang in April I was toying with the idea of combining these thoughts with Neville Higgins' findings that the twin clutch works fine with 3 of the springs removed. Would it be possible to put the pivot holes in the middle of the shoe? If so the relative position of the pivot hole/ plunger assy in C7/1 could be used in C7 with a bit of juggling. If both ends of the shoe are then made the same shape, handing them would simply be a question of drilling one end or other, requiring only one casting. I only got as far as finding where to get a bit of ally billet before the accident. Watch this space. Cheers, Stu.

 

[Bill Thomas]

Hi Bill, there is an article in "Ten Years On" p173 from MPH 597 by J. Bickerstaff, about the clutch balancing efforts of Paul Zell and Dan Smith. I have looked at this and I feel that the removal of metal alone is insufficient to achieve balance without weakening the shoe and Paul Zell's addition of weights is needed. Just before my prang in April I was toying with the idea of combining these thoughts with Neville Higgins' findings that the twin clutch works fine with 3 of the springs removed. Would it be possible to put the pivot holes in the middle of the shoe? If so the relative position of the pivot hole/ plunger assy in C7/1 could be used in C7 with a bit of juggling. If both ends of the shoe are then made the same shape, handing them would simply be a question of drilling one end or other, requiring only one casting. I only got as far as finding where to get a bit of ally billet before the accident. Watch this space. Cheers, Stu.

Morning Stu, Dave Hills told me about taking 3 springs out, And I had a very bad ride to Heaver Rally, Slipped like Mad !, I have a tuned Engine and sometimes ask too much of my bike.
I like to Play with Mod's, So I like the idea of new castings for the shoes.
Mercurycrest / John, Said add lead weights, So maybe more lead and no holes ??.
Good Luck, Bill.

 

[Robert Watson]

I balanced the clutch in the Woolly many years ago and it ran greta for a long time, and would shift well at high revs. I did it by drilling and adding weights. After probably 15 years or so I had a very difficult ride home on the last day of returning from California. When disassembled I discovered I Had that very rare two part C7 (or was it C7/1) I could live with it for a bit but you better have neutral before you got below about 10 mph.
Apparently I had been a little overzealous with the hole sizes. Ill see if I can find it in the junque pile and post a picture.

 

[Bill Thomas]

I balanced the clutch in the Woolly many years ago and it ran greta for a long time, and would shift well at high revs. I did it by drilling and adding weights. After probably 15 years or so I had a very difficult ride home on the last day of returning from California. When disassembled I discovered I Had that very rare two part C7 (or was it C7/1) I could live with it for a bit but you better have neutral before you got below about 10 mph.
Apparently I had been a little overzealous with the hole sizes. Ill see if I can find it in the junque pile and post a picture.

It would be nice to see which is the weak part, So we can avoid that bit, Cheers Bill.

 

[Robert Watson]

Like this?

 

[Bill Thomas]

Like this?

View attachment 17664

I am glad it didn't break through the pivot hole, I have drilled mine out and fitted a camshaft bush, Looks like you have too. Cheers Bill.

 

[Bill Thomas]

John, Can you show us a photo of yours, Cheers Bill.

 

[Robert Watson]

I am glad it didn't break through the pivot hole, I have drilled mine out and fitted a camshaft bush, Looks like you have too. Cheers Bill.

That was a previous repair where the pivot bolts came loose and destroyed the pivot holes in the shoes. I made a jig using a good shoe and kept boring until it cleaned up, well almost, and then turned up some alloy bushings and made them size for size and fit with loctite.

 

[greg brillus]

I asked the spares company if they could simply supply pins in an oversize, so the shoe holes could be just cleaned up and used again without bushing. This does work sort of but I have seen many shoes where the bush comes loose and then jams the pivot action. I might even just make some myself.