bsurdam91

I have a 2005 997.1S. The car is used exclusively for HPDE & track events. It is not used for races.

Symptom: Car works fine for first 4 - 5 laps. After that & while coming down front straight (135mph) in 5th gear, hard brake to prepare for end of straightaway; car is shifted into third gear and make turn into #1. Third gear engages but the clutch pedal does not return to normal position. Stays down towards floor. I have to pull clutch pedal back up with top of foot. Can then use clutch as normal through rest of track until hit front straight away. Everything starts over. Only difference in this turn is using fifth gear and moving from fifth straight to third (not over-revving)
Repairs/Attempt to Fix:
Slave Cylinder, Master Cylinder (lines all look good), Clutch, Pressure Plate, Flywheel, Crank Bearing all replaced. Multiple Power Flush/Bleeds attempted. (all done by experienced Porsche specialty shop)

At wits end on what to do next. Help!! Season is quickly disappearing and frustration already at high levels!

semicycler

997.1's have a slave cylinder bleed screw. It's common to forget this when bleeding the brake hydraulics. 997.2's have a return line and are self recirculating, so no bleeding required.

Long shot but maybe your engine mounts and transmission mounts are worn? Coming down from speed perhaps all the weight is shifting the transmission forward too much, causing radial pressure on the clutch binding it up somehow? Also look into flushing your transmission gear oil with PTX specifically as called out in the service manual. Bruce has a great thread going about it here somewhere.

Hunt3R

It wouldn't be the weirdest thing ever if the 2nd slave cylinder was also defective

floatingkiwi

You say the master was replaced? I had the same issue with a leaking master cylinder. Checked the return spring?

DC911S

Hmmm.....the brake and clutch both use the same fluid resivoir. So when you brake hard at the end of the straight, your clutch gets affected too because it (fluid) got overheated. Are the brakes fading too?

floatingkiwi

The fluid would overheat in the calipers, not the reservoir. That can't happen.

Rickard 993 Turbo

No problem with ABS and dual cylinders

provoste

Check your clutch return spring. I had this exact same symptom in my Boxster S on track. In my case, it wasn't the sequence of shifts that was causing the petal to hang- but the side-load of me pressing the clutch with the car under load on approach to the corner. The clutch return spring actually can break inside its housing, working fine 90% of the time... But under additional load on track it will bind resulting in a petal that stops about 1/2 the way back.

floatingkiwi

Also check the bottom of your master cylinder (the black plastic tube connected to the clutch pedal) for any moisture/dampness. If so you need a new master and bleed. Also as above the clutch return spring can fail causing this issue.