Ideas? Sticking clutch pedal only when braking heavily

[Oldcarguy]

Originally Posted by Blackroot

The brake fluid brand/type would be interesting if that changes.
DOT 4+ is DOT4 +
The volume isn't going to change in the master or slave with new fluid.
Might want to see if the hard line (12mm flare wrench used only) is tight. The bleeder is 11mm.
Could be many things...
1. pressure plate springs are weak or failing.
2. slave cylinder is not quite right with air bubbles.
3. Bad throw out bearing or in pieces
4. Master cylinder return spring (mentioned)

Thanks BR. Hopefully it’s air bubbles that the fluid change will take care of, but one or more of the points you mention are definitely in the running.

The thing that gets me is that it only does it in conjunction with extreme braking.

According to the paperwork I received from the PO, the clutch only has ~4,000 miles on it. But, I do have a heavy clutch pedal even though the helper spring *appears* to be in good shape & working properly, the engagement point is good, no chattering, no leakage, no gear grinding etc. If a check of the helper spring and the fluid purge with my Motive doesn’t fix the issue I may kick it over to my indie. Too many other irons in the fire and no time to pull the transaxle and redo the clutch before first HPDE in April.

Frankly I am leaning toward a hinky throw out bearing or pressure plate but I don’t get why it only happens in conjunction with extreme braking. Front motor mount is relatively new (987), but maybe a transaxle mount?? Clutch is hydraulic and the transaxle/clutch assembly is a pretty solid unit so I just don’t see a possibility there.