Clutch Hydraulics Issue? Heat Issue? Header issues?
Thread Starter
Instructor
Joined: Apr 2003
Posts: 110
Likes: 0
From: Chicago IL
Clutch Hydraulics Issue? Heat Issue? Header issues?
Driving around on the street everything is great. When I get about 15 minutes into a track session the clutch pedal does not return all the way when downshifting. It comes up about half way and sometimes pops up the rest of the way on it own or most of the time I have to put my toe under the pedal and pull it up prior to the next shift. This has gotten progressively worse over the last few track weekends.
The pedal return spring seems to be installed correctly and working.
Is it the master cylinder? Slave cylinder? The clutch itself? Something else?
One person mentioned that head from my headers could be cooking the seals in the slave cylinder. I am not so sure? Even the factory exhaust runs in that area.
Thoughts? I would hate to take apart half the car to replace the slave cylinder if that wasn't the problem.
Thanks in advance!
Steve
The pedal return spring seems to be installed correctly and working.
Is it the master cylinder? Slave cylinder? The clutch itself? Something else?
One person mentioned that head from my headers could be cooking the seals in the slave cylinder. I am not so sure? Even the factory exhaust runs in that area.
Thoughts? I would hate to take apart half the car to replace the slave cylinder if that wasn't the problem.
Thanks in advance!
Steve
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
hey steven im in the same boat. I have headers as well. I tried to insulate the slave clutch line w/ heat reflective tape (high temp stuff) and it did nothing. I bled the system, put new high temp fluid in it, etc and same result. I had my slave replaced under warranty and it also did nothing. Next I had a new LS6 clutch put in (i had to pay for the clutch but the labor was under warranty) and that fixed it> I should NOT have had to pay this, but now the problem is back after 6k miles and Im going back w/ the car to the dealer AGAIN. Im going to latoff chevrolet in arlington heights, il.
Dave
Dave
Last edited by T_Vert; Oct 25, 2004 at 12:03 PM.
Drifting
Joined: May 2003
Posts: 1,551
Likes: 0
From: salt lake city UT
I have an o2 zo6 clutch in my 500/500+ rwhp/rwtq car with headers and everything. I live in Fl...so heat is an issue. I only get the peddle problems in the hotter months. so heat is the prob. also when the color of the fluid is dark, i take a turkey baster and suck out as much of the clutch fluid as i can, wipe clean the res, and put new fluid (same as gm) dot 3 brake-clutch fluid, pump the peddle a bunch of times and you are good to go. reepeet the process when the fluid get dark. this fixes the prob! 
Thread Starter
Instructor
Joined: Apr 2003
Posts: 110
Likes: 0
From: Chicago IL
I have bled the entire system a couple of times with ATE Super Blue brake fluid - no difference. I insulated the line - no difference.
I understand that it might be heat, but what is causing it to only happen now, or to Dave after 6000 miles? I have had the headers on for several years and am only now having this issue????
Master Blaster - what fluid are you using? Thanks!
Steve
I understand that it might be heat, but what is causing it to only happen now, or to Dave after 6000 miles? I have had the headers on for several years and am only now having this issue????
Master Blaster - what fluid are you using? Thanks!
Steve
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
well ive got the lapd bleeder and completly flush the fluid and the problem is just as bad as it was w/ the old fluid in it. Ive completely insulated my lines and its still there so i cant see heat having anything to do with it. IN theory if its heat related, you fire up the car and go WOT the lines can no way be heat soaked enough to cause this yet my pedal will stick to the floor after one pass just starting the car.
Dave
Dave
Thread Starter
Instructor
Joined: Apr 2003
Posts: 110
Likes: 0
From: Chicago IL
Interesting. Mine works great for the first 2 or 3 laps at Road America, then it starts acting funny and staying on the floor. I actually thought about retrofitting a second or larger spring on the pedal because it works great if I simply pull it up with my toe. But it is still bugging me why mine works fine on the street...........
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Have any of you tried the drill mod on the line that connects the slave to the master or purchased pre drilled line that already has the two restrictions drilled out. A while back someone said that solved their problems.
Bill C
Bill C
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
drill mod was done by the dealer, but its my understanding that you cant drill out 2 spots on the stock cable. If i could find out if the fbody one would work, i would try it in a heart beat.
dave
dave
Drifting
Joined: May 2003
Posts: 1,551
Likes: 0
From: salt lake city UT
Originally Posted by Stephen L
I have bled the entire system a couple of times with ATE Super Blue brake fluid - no difference. I insulated the line - no difference.
I understand that it might be heat, but what is causing it to only happen now, or to Dave after 6000 miles? I have had the headers on for several years and am only now having this issue????
Master Blaster - what fluid are you using? Thanks!
Steve
I understand that it might be heat, but what is causing it to only happen now, or to Dave after 6000 miles? I have had the headers on for several years and am only now having this issue????
Master Blaster - what fluid are you using? Thanks!
Steve
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Originally Posted by Stephen L
Driving around on the street everything is great. When I get about 15 minutes into a track session the clutch pedal does not return all the way when downshifting. It comes up about half way and sometimes pops up the rest of the way on it own or most of the time I have to put my toe under the pedal and pull it up prior to the next shift. This has gotten progressively worse over the last few track weekends.
The pedal return spring seems to be installed correctly and working.
Is it the master cylinder? Slave cylinder? The clutch itself? Something else?
One person mentioned that head from my headers could be cooking the seals in the slave cylinder. I am not so sure? Even the factory exhaust runs in that area.
Thoughts? I would hate to take apart half the car to replace the slave cylinder if that wasn't the problem.
Thanks in advance!
Steve
The pedal return spring seems to be installed correctly and working.
Is it the master cylinder? Slave cylinder? The clutch itself? Something else?
One person mentioned that head from my headers could be cooking the seals in the slave cylinder. I am not so sure? Even the factory exhaust runs in that area.
Thoughts? I would hate to take apart half the car to replace the slave cylinder if that wasn't the problem.
Thanks in advance!
Steve
The only fix is to to replace EVERYTHING! Seriously.. GM has a tech bulleting out on this. I tried for 2 years to fix this and tried all the things below. The only thing to fix it was to replace everything.
The problem starts with the clutch pressure plate and the way its mounted. Something to do with the way if was torqued. It causes a wobble binding and will not release the pedal..Once this starts happening the Slave is trashed so that needs to be replaced too..
Things it is NOT and Things that Wont fix it for good
Over heated Hydraulic fluid ( I currently use ATE Super Blue)
Not heat related (I have LT Headers)
Loose Pedal return spring (Never did it. Nothing to do with it)
Master Cylinder (first thing they replaced)
Hydraulic line Drill Mod does nothing ( Second attempt I did that too)
Trust me.. I have done them all.. If you take it to the dealer and you still have the problem it means they lied and did not replace EVERYTHING like the bulleting states...
This includes, Clutch, pressure plate and Slave
Last edited by chuckster; Oct 25, 2004 at 10:51 PM.
Instructor
Joined: May 2001
Posts: 184
Likes: 0
From: JC TN
I have had the same problem with my 03Z...When under boost in 4th==the pedal would go to the floor and i would have to pick it up with my toe..i am redoing the motor and putting the exedy twin disk and modifying the master slave----hope it does it but dont know..My last 02Z did it too--dealer replaced master and slave==problem went away but i traded the car too soon--they left alot of lines not tightened and worried me--i dont trust my local dealer with my car...Dave 
Thread Starter
Instructor
Joined: Apr 2003
Posts: 110
Likes: 0
From: Chicago IL
Thanks Chuckster. Deep down I was thinking that might be the case, I was just hoping it wasn't.
So - Now that I am replacing the clutch, pressure plate etc. What are the best parts to use? Is there an aftermarket pressure plate that is not prone to binding? Is GM the only source for the slave cylinder? What is the best clutch for a car that sees track service with about 450 RWHP?
Thanks!
Steve
So - Now that I am replacing the clutch, pressure plate etc. What are the best parts to use? Is there an aftermarket pressure plate that is not prone to binding? Is GM the only source for the slave cylinder? What is the best clutch for a car that sees track service with about 450 RWHP?
Thanks!
Steve
Instructor
Joined: May 2001
Posts: 184
Likes: 0
From: JC TN
Alot of options for clutch--actually a stock z06 clutch works upto 450 hp pretty well...you modify the master/slave your self by drilling..should be someone here to help you with that..i honestly think it is between the hydraullics and pressure plate...DAve
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Originally Posted by vetteturbo
Alot of options for clutch--actually a stock z06 clutch works upto 450 hp pretty well...you modify the master/slave your self by drilling..should be someone here to help you with that..i honestly think it is between the hydraullics and pressure plate...DAve
What it does do is allow the clutch to engage more abruptly. Tends to Shock the drivetrain a little more on quick releases..
Kinda cool racy feel
.. But alas... The pedal will still stick.. 
Melting Slicks
Joined: Aug 2002
Posts: 3,333
Likes: 1
From: Central NJ/PA
Originally Posted by vetteturbo
Alot of options for clutch--actually a stock z06 clutch works upto 450 hp pretty well...you modify the master/slave your self by drilling..should be someone here to help you with that..i honestly think it is between the hydraullics and pressure plate...DAve
Heat+ spring+time=failure
Drifting
Joined: Mar 2001
Posts: 1,471
Likes: 1
From: Pensacola FL
Ya- i had the same problems & got tired of trying all the little things. Replaced everything with 04 Z06 parts and had work done by local vette shop. I made sure to point out the torque specs & tightening sequence. No problems since. Scott