So this past weekend at Mid Ohio my clutch started acting up. On track it would slip just momentarily when upshifting, but I was able to drive around this by simply releasing the clutch slightly earlier in my shift.

Then, for the honda challenge race, we do standing starts. Awful slippage. When I launched it basically slipped straight to the rev limit, so I shifted to 2nd, straight to rev limit, and same thing again in 3rd. I put it in 4th and gingerly applied the gas and it was fine, and once it cooled down a bit it gripped for the rest of the race normally.

Anyway, I pulled the trans and pressure plate today. Clutch disk looks perfect, right at oem thickness, nowhere near the service limit. A little bit of burning on the pressure plate and flywheel, as would be expected. I can't figure out why it would be slipping. Everything was dry in there, no oil, no leakage from the rear main seal.

I found a couple old threads about people saying it's the master cylinder going bad, and they would bleed the clutch and it fixed their issue. I have plenty of fluid in my reservoir, though I did notice a tiny bit of wetness/oily residue where the shaft enters the master cylinder under the dash. I could see a sticking master cylinder cause the clutch to slip due to it releasing too slowly, but I don't see why a miniscule amount of oozing over several years would make a difference. I need to decide if I want to just put it back together and try a clutch bleed, or if I want to buy >$500 in new parts to install while I have the trans out...

Have any of you ever experienced similar issues with your S2000?

 

AP2s (and maybe 2003 AP1s?) have a restrictor built into the clutch hydraulic line to prevent the clutch from being released too quickly. This was in response to the large number of diffs getting grenading by people launching on them in AP1s. Evo 8s also have a similiar clutch restrictor pill built into the line.

There's a DIY on how to remove it. Or you can buy the AP1 assembly that doesn't have the restrictor in it.

As fro the clutch MC, they are known to go bad. Mine has leaked a little bit.

As for my clutch on my 2005, it'll slip on a fast 3-4 shift, and 4-5 first. This is not power shifting, just getting back on the throttle while letting the clutch out. So I've had to learn to shift slower on those shift to prevent slip.

 

How many miles are on the mc and slave? Id replace the slave and bleed just out of good practice. Is the flywheel glazed?

 

I have an AP1 chassis, so no delay valve. I have over 5000 track miles on this car and never an issue before.

As for total miles on the master and slave cylinder, the odometer is around 115k miles I believe. There is some burning on the flywheel, unfortunately.

 

Do you have an AP2?

The clamping force is kind of weak. It's possible if it was slipped a few times in the past that the springs can't hold from heat fatigue.

It's different than glazing the plate. Only fix is to replace stuff. I've had to do that once.

 

AP2 motor, but AP1 flywheel. Are the pressure plates different between AP1 and AP2 then. If they both bolt up, I don't know which pressure plate I have.

Was there any visible damage to the spring fingers that you were able to see to tell if they were heat fatigued?

 

They were discolored, IIRC. Blue'd a little from heat. I just never got the clamping force back and when I opened it up all the friction components were fine.

 

that is weird mine span like you describe it was completely f-cked the disk was done the PP to

 

I've had that happen too. The SSM car used up clutches and brakes like water...

 

I'll shoot some photos in a little bit here. My disk looks fine, still at 8.14 mm, new is 8.2-8.9mm, service limit is 6.0mm. Just the burning marks on the metal surfaces, which you would expect since it had been slipping and making heat. The fingers don't look discolored though, so I don't think it got too hot.