Listers,
Before I charge off and buy a new clutch, I thought I'd see if anyone can
cast a new light on the problems I am having.
The GT6 uses an overdrive 2500 sedan gearbox (basically a TR6 unit), and
clutch.
Recently the clutch started to fail to completely disengage, started suddenly.
Since nearly everything is near new (hydraulics etc), I immediately thought
that the bolt in the clutch fork had sheared. Well I was wrong, dismantled
the car this afternoon, and that little sucker is o.k.
Here's the state of play.
The hydraulics are fine (before I went to the trouble of dismantling the I
checked first!). I use the GT6 Master and a sedan slave (same id as the gt
slave) I get approximately 1/2 inch of movement of the piston.
The arm on the cross bar for the clutch fork is a strange S shape (so that
it will miss the chassis of the GT6), and there is only one hole (is in the
end). This arm was created from a sedan unit, the centre of the hole in the
arm is 62mm from the centre of the shaft (I beleive this is much less than
even the furthest in hole would be on the original arm).
The two above mean that I should have more than enough movement at the
throw out bearing to release the clutch. The pistone operates in the middle
of it's throw, not at either end, so piston stop shouldn't be a problem for
full engage or disengage.
The clutch friction plate I compared to a new item I have (for a new motor,
when I finally get it finished), and it's is not excessively worn (there is
a lot of red friction material dust though!). It is a PBR item (local
Australian made)
The flywheel face was machined lightly before being installed (unlike the
back of the flywheel which was heavily machined, the sedan has a very heavy
flywhell!). It looks o.k., except for the clutch bolt that broke when I
tried to get it out! - back to the machine shop we go!
The pressure plate is a Borg and Beck 8-8.5 inch unit. This is I belive the
culprit. The contact surface has worn, with a number of smooth grooves
running around it. The fingers on the diaghram are fairly worn where the
throw out bearing has made contact, maybe 1/3 of the way through. It was
not brand new when I put it in (came with the gearbox), but not this bad
either. Anybody got a suggestion?
I will go an obtain a new pressure plate monday, as we need the car. I was
hoping that the clutch (and motor) would hold on until the new one is
completed!!!!
Bill and Sal Birney
Melbourne, Australia
'67 Spitfire MkII - Under resto
'70 GT6+ (RHD)
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