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Re: Very odd clutch problem

PostPosted: Wed Feb 10, 2016 1:59 am
by Charlie Tolman

Is there anything suspicious regarding the clutch pressure plate mechanism and housing, which might be responsible in damaging the carbon throw-out bearing material ?
For example, does the central contact region of the clutch have any out-of-plane wobble ?
Is there a fluid leak of any kind that has befouled the carbon material ?

I had a clutch that broke some of the straps between the pressure plate and its housing, and it became unbalanced, causing a pretty nasty vibration. At speed, in a few minutes of the race, the vibration broke internal wiring in the starter motor, which was discovered after the race. This might not be related to your problem, and I mention it only as a remote possibility.

Does some company make a clutch release system where the clutch cylinder is mounted inside the transmission bell-housing ?

Charlie T.

Re: Very odd clutch problem

PostPosted: Wed Feb 10, 2016 10:06 am
by Asolepius
How can I get this forum to email me when someone replies?

I think there were 2 causes. First, the clutch fork was off centre. It didn't look bent, but careful measurement revealed that the release bearing was maybe 5mm off centre from the gearbox input shaft. I have a spare fork that was better, but still about 3mm off. So I have `adjusted' that one (don't ask) and it's about right. It also has a new bush, so is as good as these things ever are. Also, the word on the street is that the carbon bearings are terrible quality these days. People are replacing them after 200 miles. So I am fitting a roller bearing - the Ford type for Pinto etc. It just needs a carrier fabricated from a steel plate. It won't run exactly concentrically of course, but several guys have done this and they get away with it. Lasts far longer than the carbon ones. As a precaution I'll spray the release pad and the bearing with resin bonded PTFE dry lubricant, which should mitigate the eccentricity.

Yes, you can get a concentric release cylinder that fits in the bell housing: ... ts.htm#5.6

But you have to use a Formula Junior clutch. I yearn for the days when parts were of such quality that you could fit and forget.