Z06FROMHELL

everytime i go to the track on the 3-4 shift the pedal feels real soft. like there is no resistance, it has even stuck to the floor. never does this in day to day traffic. the car has howver, since i bought it used (02 z06 37000 miles) had a very jerky clutch. never had this issue with my ls1 fbody's. thought it might just be the tighter z06 clutch. but it seems like the clutch is either on/off. kindof a byotch to drive in town traffic till you get used to it. any ideas? is this a common problem?

also, might be related but the car has always been hard to get into reverse? all other gears okay. it was tough with a stock shifter but is really a pain with the hurst it has now. is there some adjustment or something i can do. i consider myself a very good mechanic, just not familiar with the quirks of my first y body car. any help is appreciated.

RiceEater Z06

sounds kinda like a bad slave cylinder

vetteheadracer

I had this exact same problem, it turned out that where the master cylinder connects to the actuator there is a baronet type connector with a plastic seal inside it. The plastic seal would get hot next to the exhausts and would start to go soft meaning the baronet connector would expand hence you loose pressure in the hydraullics.
You might also check you have good clean fluid up to the level in the master cylinder.

Z06FROMHELL

thanks for the ideas. ive read a lot since this post about bad clutch fluid causing all kinds of issues. im going to try a thourough flush of my clutch system and retry.

on the seal swelling issue. would replacing the master cylinder assymbley take care of this issue?

master blaster

its hard to believe , but i have an o2 zo6 clutch on my 650 rwhp c5
and had the sticky peddle probs for over a year. it was worse in the heat.
i removed the spring and it fixed it 100%!

Z06FROMHELL

what spring did you remove, im unclear on this......

Z06FROMHELL

wouldnt removing the spring keep the pedal from coming back up?

t56gen3

The spring is there to assist in holding the clutch to the floor, like at a light. Many have taken it out and prefer it without, but it makes the pedal a little heavier. I too plan to do this when I get time.

Z06FROMHELL

flushed my system really good yesterday. i have a vacum tester with a one man brake bleeder kit. worked like a champ. filled with new fluid, pumped like 50 times and did it again. i had a lot of black mud looking stuff in the bottom of the resevoir. now its 100%clear. will probably do it again in a month or so.

also pulled out the spring on the clutch pedal. this is a super easy, 30 second deal. i cant believe i havent done this sooner! clutch now feels linear instead of on/off. you can control the amount of slip at launch. easier to take off in town with a little slip instead of the drop the pedal feel with the spring. best free mod out there. (other than a procharger for a birthday gift)

plan on getting back out to the track to test the work you guys have inspired me to do. but my thoughts are its fixed. thanks.....

Ranger

If you plan to do launches, suggest you keep close watch on the clutch fluid in the master cylinder.

At the first sign of it taking on color, I remove the fluid from the reservoir and replace it with fresh (brake) fluid.

I've been following this practice through 300+ passes and my clutch pedal has remained normal.

Ranger

ZO6Les

Flushing the sysytem is a great start - these cars are VERY sensitive to dirty fluid. I would also recommend using a syringe or small turkey baster and change the fluid in the resevoir before AND after every track event, as well as every oil change. It take 5 mins, and IMHO well worth it.

Les

slong

Good evening Les And Ranger. Hope all is well with all your way. I have been doing this to and have had no further problems. One thing is for sure, when the clutch does get C/O, I'm going to run an external bleed valve from the slave cylinder. Now that will be nice.

ZO6Les

Hi Steve ... long time - I wish I had the external valve put on when they did my clutch - next time for sure!

Les

Ranger

Hey guys.

When I swapped on the clutch for whoever will be the new owner, we installed a remote bleeder and insulated the clutch fluid lines with Cool-Socks. This should help keep the heat off the fluid.

Ranger

ZO6Les

I like the idea of the cool socks on the lines ... I may try that too - thanks!

Les

slong

Going there too. Thanks,
slong

GeorgeZNJ

you guys have given me ideas of what to look for, thanks for the info. my clutch is soft after 3-4 passes

Vegas Vette

It worked for me also..

lytmup

This is a problem called the "GM makes ****ty clutches on performance cars" problem.

I had the same EXACT problem. After much research and playing around with new slave and master cylinders, different hydraulic fluid, bleeding, etc. , I found a local TV car talk guy local to my area (also has a Motor Trend show on Speedvision) that knew what the issue was. I had emailed him, and to my surprise he responded with the correct diagnosis.

He said that GM made some terribly designed clutches on 02 and before 6 speed trannies (both Vettes and Camaro/F-birds). He basically said that the clutch was so poorly designed, that during heavy acceleration, that the clutch loses ALL abilty to return properly due to the centripetal forces acting on the clutch. He recommended to me a heavier duty clutch (ie. Centreforce dual friction) to cure the problem. He was right on the money.

I replaced my clutch with a Centreforce dual-friction and the problem disappeared, not to mention that now I have a much heavier clutch (which I like personally than the light OEM feel).


BTW, there is also another stupid design thing that GM did with the 6-speeds. They put a restrictor plate in the clutch line to restrict hydraulic fluid to and from the master cylinder. Why they did it is a mystery, but I drilled that out as well (i dont have the link handy, but do a google on "GM clutch drill mod" for more explanation.)

Hope this helps. Good luck.

UVETTYA

What fluid are you using? I've heard that DOT5 will eat rubber.