Burman clutch
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- Joined: Mon Sep 13, 2021 5:25 pm
- Location: Hertfordshire UK
Burman clutch
Hi all I have a 1952 model 20 with Burman b52 gearbox and clutch, I have just replaced The clutch friction plates and plain plates 0.138 thou thick. My problem is the last friction barley locates in the basket, when you pull the clutch it allows it to pop out rotate and jam causing slipping. Is it ok to use a combination of the thinner 0.060 thou plates ?
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Re: Burman clutch
Just looked at one of my old tired clutches, and all the plains in the box are 60-70 thou and are what I must have been using for 45 years. There is - I am pretty certain - a fatter 'stepped' plain one at the bottom of the stack that's actually on the bike (but haven't got a loose fat one to measure).
Chainwheel depth is 36.5mm give or take. The ones on singles, or some singles, were shallower I think, but don't have anything to compare. A mismatch there would cause grief.
At 60-odd thou, the chainwheel should take the full complement, with new friction plates if they are to spec. But nothing wrong with using a thicker one somehere if it gets the pressure plate adjuster and pushrod into a better place. The stack has to be thick enough to compress when 'in' and disengage fully when 'out' without the outermost plate going AWOL as per your problem, with the operating bits in sensible 'mid' positions as it were.
Chainwheel depth is 36.5mm give or take. The ones on singles, or some singles, were shallower I think, but don't have anything to compare. A mismatch there would cause grief.
At 60-odd thou, the chainwheel should take the full complement, with new friction plates if they are to spec. But nothing wrong with using a thicker one somehere if it gets the pressure plate adjuster and pushrod into a better place. The stack has to be thick enough to compress when 'in' and disengage fully when 'out' without the outermost plate going AWOL as per your problem, with the operating bits in sensible 'mid' positions as it were.
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Re: Burman clutch
You may find that new-style friction plates are thicker than the originals with cork inserts. You could try using a thinner steel plate somewhere in the stack, or even an older friction plate in place of one of the new ones. If confident to do so, you could sand off some of the friction material
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Re: Burman clutch
I would check the clutch basket and the clutch boss match. It could be that 4 plate and 5 plate components are mixed
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- Posts: 11
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Re: Burman clutch
All sorted now i resorted to skimming 0.2mm of each friction plate giving me 1mm overall which cured the proplem