[TR] clutch hydraulics query

[jimmuller at rcn.com]

I drove my GT6 in to work this morning.  I'm happy to report that the gearbox worked just fine.

I must report unhappily that the clutch is more needy, which is to say less clutchy.  It's a problem I've wrestled with before.

As I'm driving it seems to build pressure in the hydraulics so that eventually the clutch slips.  The quick fix is to crack open the nut where the line goes into the master cylinder, allowing a teaspoon or so of clutch fluif, which is to say brake fluif to escape.

It did this a few days ago on a brief drive.  It did it again this morning while I was tooling down the highway.  A common condition for most occasions that I recall is that it was cold when I started out.  And I suspect that if I mash the pedal down too hard it can bring on this condition.  Or least not mashing it hard seemed to have avoided it for a long time.

I'd suspect a sticky slave cylinder except that this morning it seemed to have come on when I wasn't using the clutch at all.  At least not that I recall.  Okay, maybe once.  An alternate stickiness factor could be the clutch arm scraping against the tunnel cover.  I can check it but it's one of those space-age plastic covers with no dangling insulation underneath, so I doubt this possibility.  It really seems to correlate to heat.

So the question:  Is there evidence to suggest that brake fluif expands noticeably with moderate heat?  (It isn't getting especially hot.)  Perhaps older fluif that might have absorbed water sitting even in an opened once but tightly sealed container?

Of course, the obvious fix is just to purchase new cylinders, clear out the line, then use DOT5.  Spitbits lists the SC at about $50, the MC OEM for about $150 and MC repro for about $65, IIRC.

tanks,
Jim Muller
'70 GT6+
'80 Spitfire