TommySalami

My old clutch started slipping bad so I had it replaced a few months ago and got an ACT street disk clutch/PP and resurfaced OEM flywheel. The clutch has about 2000 miles on it now. When the car is cold, the clutch feels soft at first, and engages closer to the floor, similar to what I remember of the OEM clutch. After driving for an hour or two, the softness in the pedal goes away, but the clutch engages much higher. After autocrossing, the clutch engages VERY high. It does not slip at all, cold or hot.

Any idea what's going on here? I've heard air in the clutch will cause it to engage low, and that a worn clutch will engage high, but the clutch is definitely not worn.

Saki GT

I'd rebleed the system.

TommySalami

Gonna try it tomorrow.

TommySalami

Ok, took me a while to get to it, but I have the problem narrowed down.

The problem is that the slave cylinder is extended too far out in its normal position. I took the slave off, opened the reservoir cap, and could not compress the piston on the slave in order to get it back into place against the release arm of the clutch. The only way I could get it to compress even a little was to open the bleeder valve and let fluid out.

I believe what is happening is that the slave to be pushing on the clutch arm and is causing the clutch to sit slightly disengaged most of the time.

It is an AP1 slave on my AP2. When I had the clutch replaced, the shop replaced my slave cylinder as well. Their reason for replacing it was that it would not freely move, which I think is the same problem I'm having. This leads me to believe the problem is somewhere before the slave, and is what caused my original clutch to slip. The master cylinder does not leak any more than a slight teardrop of fluid that just hangs there, no fluid dropping onto the carpet.

The clutch fluid also does not gravity bleed. If I open the cap to the reservoir and open the bleeder valve, nothing comes out.

Any idea why this would happen?

chris_barry

Check that the pushrod on the MASTER cylinder has no pressure on it when the pedal is at rest. If there is any push on the piston in the master the piston moves to cover the small hole back to the reservoir. This makes is impossible to push the piston back into the slave without cracking the bleed nipple. It can also cause the clutch to start slipping when the fluid heats up, expands and cannot find its way back into the fluid reservoir.

I see this on race cars when people adjust all the free play out of the pushrods on their master cylinders. When the calipers heat up the fluid, the brakes jam on and they expand the fluid more. One customer was complaining that his car was down on power after the first lap, and it was running really hot. He would actually boil the radiator fighting the poor engine against the jammed brakes.

TommySalami

This was it! I had free play in my clutch a while ago, adjusted it out with the pushrod, and right about then the clutch started slipping bad. Figured I'd toasted my clutch (I was new to stick) and got it replaced, and have had the problem of the clutch slipping when the fluid heats up. Just went out and added a little free play back in, and god dammit it works now! Sonofabitch rod adjustment cost me $1300 and months of frustration!!!

Sir, I owe you a beer.

chris_barry

Glad to help. Virtual E-beer accepted and consumed.

4forall

Beer is good!

I was thinking of making an E book of just the top 100 things to know when purchasing any car that isnt ecno/family/pickem up truck. I know i have learned my fair share of small things over the few years i've owned my s2k.