One thing I have not seen mentioned in detail as far as clutch
engagement goes is wear in the clutch pedal assembly. In my TR-4, this
unit was both worn and corroded, to the point where I could not
disassemble it to re-bush the shafts. I had to find a good used one, and
then replace all the bushings. This made a great deal of difference -
although the old unit had looked like it was working fine, the
accumulation of wear in all the separate places added up to a surprising
amount of slop and clearance, to the point where the clutch master was not
being pushed in far enough to make the slave cylinder go out. Once I did
the rebuild, it was like I had a new clutch - the improvement was amazing.
One other minor point on bleeding - the slave cylinder can be mounted
two ways, with the bleeder either towards the top of the car or towards
the bottom. The correct position is with the bleeder on top, but on my
car (DPO!) it had been put on the other way. One can see why - with the
bleeder on bottom it is much easier to reach, since the hose from the
master cylinder is not in the way. However, the bleeder has to be on the
top to work, since air is lighter than clutch fluid, and with the bleeder
on the bottom, some air remains trapped in the slave cylinder no matter
how long you bleed the system.
Anyway, I was originally convinced my clutch was bad, but after these
two repairs, it worked great, and I didn't have to take the engine out of
the car. Not that replacing the clutch pedal assembly was a piece of cake
- I did it myself, but it would have been a lot easier with another person
helping, and it requires a bit of time stuffed up under the dashboard -
was dwrn well worth it, though.
______________________________
Dr. Mark Clark
Oregon Institute of Technology
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