Fireescape

Before I had my motor built I was running a Exedy HD clutch, which worked well, bar smoking every time I had to slip it. I had my motor built and had my clutch replaced with a NPC (Aussie brand) Heavy Duty 5 puck ceramic button clutch. Ever since then I've had this strange engagement issue.

About half the time, when I release the clutch pedal as I move from a standstill, the clutch engages with the pedal about an inch of the floor. As I continue to release the pedal the clutch disengages and then re-engages again at the normal pedal position, 3 or so inchs off the floor. This causes no end of issues, if I don't rev the car on the first engagement the car starts to stall, but as I continue to release the pedal the car revs rise massively as the clutch disengages, so I lift my foot off the throttle, the clutch re-engages and I almost stall the car because I've just released the throttle, it's a major pain! In every other way the clutch is perfect, no other problems changing gears, even at 8500rpm.

I actually went as far as removing the gearbox (a four day epic in my garage) and checking the throwout bearing, splines on the gearbox shaft and the clutch itself. All looked fine (clutch has about 6K on it). I replaced the flywheel, which wasn't replaced when the new clutch was installed, but other than the hotspots on the flywheel, everything was good.

I reassembled the clutch and reinstalled the gearbox, but the problem is still there. So next I spent a lot of time bleeding the clutch, following the TeamRip instructions, but I'm still having the same issue, even though I thought it was slightly less prevalent. The only thing I haven't done is replaced the clutch master cylinder.

I find that when I pull up, if I put the car in neutral and fully push the clutch pedal in and then release it, push it in again and put the car back into 1st gear the clutch releases in a normal manner.

Has anyone heard of this kind of clutch issue before, I'm reluctant to just replace the master cylinder hoping it will fix the issue, but I'm running out of ideas.

barneyb

Crank walk???

Fireescape

Crank walk? I'm not sure if the only outward sign of crank walk would be a strange issue with the clutch sometimes. Is there any reason you think it could be something like that. I was just thinking some issue with the master or slave cylinders.

barneyb

I never heard of a double engagement point before. It is an extremely odd symptom. It could be something to do with the master or slave. The engagement point changing could also be caused by the flywheel changing its position. There's probably other things I haven't thought of. The thing is, checking for crank walk is easy, nothing needs to come apart. If that is not it, look elsewhere.

This reminds me of a story.....
This guy writes saying he is having problems with clutch engagement. I suggested he look under the car at the slave while someone works the pedal. He wrote back asking if the entire transmission was supposed to move when the clutch pedal was depressed. As Eric O would say, "There's your problem lady!"

Fireescape

Well I checked for crank walk, having a mate push on the clutch and using a pinch bar to try and move the crank pully away from the block. Couldn't feel or see any movement at all, so I'm thinking my issues aren't caused by crank walk. So I'm pretty much left with a faulty clutch master, or slave cylinder, unless anybody can come up with another idea. I'm not sure if there's any way of telling if the master cylinder is faulty, bar replacing it. Mine seems ok to look at, no leaks or anything, and I always have good pedal pressure... it's very strange to say the least.