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clutch questions

To: triumphs@autox.team.net
Subject: clutch questions
From: "Jim Muller" <jimmuller@pop.mail.rcn.net>
Date: Sat, 03 May 2003 17:20:10 -0400
Fellow Triumphisti, a duo of queries if you don't mind, re the clutch 
on my '70 GT6+, or more precisely re its actuating mechanism.  I've 
asked about these issues before, but since I have been unable to 
resolve things fully I'm asking again.  (Mostly I'm looking for 
understanding.  Wisdom is apparently beyond my meager capacity.)

Ever since the gearbox blew itself up a year ago and got both itself 
and the clutch replaced I've had two annoying issues.

The first is a chirping TO bearing when the clutch is engaged and the 
car is cold.  Depressing the pedal a bit makes the sound change; more 
pedal makes it go away entirely.  As I drive in the morning and the 
clutch system develops more pressure from use, the chirp goes away.  
When I first installed the clutch it didn't make this noise, and the 
explanation I got from you was that grease from my fingers lubed its 
surface, but that said grease quickly wears away.

This is one those "self-adjusting" clutches that is supposed to keep 
the TO bearing in contact with the finger springs (or so I was told, 
though I got highly conflicting views from different people).  I even 
tried installing a very light spring to maintain this contact; it 
made no difference, perhaps because it was too light.  (I would've 
thought any contact at all should keep the bearing spinning.  But 
admittedly, the noise would change but not go away entirely with 
slight pedal pressure.)  The final explanation I got from you was 
that this noise was typical of a bad TO bearing.  I had originally 
installed a Q-H clutch, then swapped it for a B&B, but I didn't swap 
the TO bearing because they were same RHP part.  The noise was the 
same with the second clutch.  I was told that these bearing were 
generally good but that bad ones were not unheard of.

So today I pulled the tranny yet again (I'm getting good at it!).  On 
Monday when the local machine shops open I'm going to find someone 
with a press to swap the bearings on the brass holder, then re-
install.  But I'm getting tired of pulling the tranny and busting my 
hands in my garage on beautiful spring days.  I want to understand 
what's happening.  I can't see or feel anything wrong with the 
previous bearing.  It is not totally free-spinning but I don't know 
how much drag is normal.  It has no feelable rough spots.  Is it 
indeed true that a TO bearing can be bad with no detectable flaws 
until it is installed?  Master, how can this be?

The second issue is that the hydraulic system seems to build up 
pressure with use, as if it were not releasing fully so that 
successive operations push more and more fluid into the line.  When 
it gets enough pressure, the clutch slips, and I'm forced to pull 
over and crack the nut holding the line to the MC to release 
pressure.  It seems to be a worse problem when the car is hot.  I 
went through much of last summer with no problem, but it seems to be 
back now.  I went through this with my Spitfire many years ago.  A 
mechanic to whom I had taken the car for some other job I didn't feel 
like doing myself actually fixed it, but he didn't tell me what he 
did.  I've always believed that he moved the SC inward its pinch bolt 
so that the piston operated in a range further down toward the closed 
end of the SC's bore.  However I really don't know, and in any case, 
this option isn't available on the GT6 because its SC mount is fixed.

So I'm open to suggestions.  What causes this and what might I do 
about it?

Tanks very much!

-- 
Jim Muller
jimmuller@pop.rcn.com
'80 Spitfire, '70 GT6+

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