Sticking clutch pedal write-up

**fbodynut** · 10-20-2007, 03:49 PM

Well today was the big test. I rolled over 400 miles on the new clutch set up today. And as of right now, everything is 100%. I went through the gears high revs and quick shifts several times with good results. Tomorrow I will give her some more of the same. It pretty much has to work...it is all new.

I know I went a little overkill on the set up, but the centerforce dual friction will handle all the horse power I will ever throw at it. And a lightweight flywheel is worth every penny.....not for everyday stop and go traffic though.
So I'm happy for now.
My opinion on all this is if your pedal sticks, I would replace the whole set up,master,slave,pressure plate, and disc. Flywheel optional.
Time to go do a few...

Oh yea, and keep the fluid flushed.

**fbodynut** · 10-21-2007, 09:13 AM

Clutch definately works 100% Made several more high rpm shifts and all is well. Oh and a 3k launch and feathered the go pedal to keep off the rev limiter for about a 100ft. Yes I paced it off. See ya around the board.

**JonB** · 10-21-2007, 11:06 AM

^^^
That's A sweet picture.

**fbodynut** · 10-21-2007, 02:11 PM

Thanks, had to put things to the test.

It took alot of restraint not to go full throttle for 400 miles. I hope everyone else gets theirs worked out too.

**JonB** · 10-22-2007, 03:13 PM

Some new info I've found on what causes this problem when the slave goes out. For what ever reason I can't edit my original post to add it to the actuall write-up so It will just have to go here.

The slave cylinder is what pushes on the fingers of the clutch to make it release. In the flawed part, when the clutch gets hot, the heat is transferred to the slave cylinder, causing the piston inside the slave to expand, and it binds in its bore, causing the clutch pedal not to be able to come back up.

**fbodynut** · 10-22-2007, 03:39 PM

Hey John,
That sounds like a very good explanation of what could be happening. I really felt the problem was related to the slave, binding up in some way.

**'00T/A** · 10-29-2007, 04:11 AM

hey JonB that was a great write up man exactly what i needed, thanks alot

**'00T/A** · 11-13-2007, 05:00 PM

this definatley deserves a sticky

**siggs229** · 12-12-2007, 12:56 AM

Well im glad those repairs worked for you guys . I have a problem with my clutch too. Most of you were talking about how your pedal would stay down or release slowly . My problem is differnt and Im wondering if the drill mood would help . My clutch only slips when I am shifting at high rpm with my foot to the floor

: . It slips going into second and going into third . Slips for a bit then grabs. My clutch never slips at any other time ( low rpm high gear ) . Now my car is a 2002 and has only 4700 miles on it , fluid is good . Could my clutch be shot already ??? I have mods on the car , im making 361 hp and 374 tq at the wheels . Is the clutch just weak and cant handle the extra power and better traction with suspension mods I have , control arms , sub frame , torque arm . I mean my car has the Z06 clutch , it should be able to handle this , shouldnt it ? Well hopefully someone will have a good answer for me . Thanks ,

Rob

**menardst** · 01-09-2008, 02:44 AM

Originally Posted by menardst

Not sure if this is fact, but it seems to relate.

I have changed my master cylinder after my clutch pedal would stay at the floor... and I noticed black fluid in the resevoir. I tried bleeding first and then replaced the MC. Still no clutch. So I figured it was the slave cylinder. I then replaced the clutch and slave cylinder. Though my clutch no longer stays to the floor it still does not feel solid. Yes, I may have air in there still but... if not here is my concern....

On my 86 trans am I had a problem with my right front wheel sticking when I used my brakes. Over a few months it got so bad that when I pressed the brake pedal my tire (actually brakes) locked up. The fix was my flexible brake hose that went to the caliper. My understanding is that the inner part of the hose swells after use (heat, cold, pressure, and eventual breakdown of material) and causes a restriction that does not let fluid back to the master cylinder or does so very slowly.

COULD this be the same occurance in the F body clutch problems, especially when there is black junk in the MC? I took apart my original clutch MC and found a bunch of black goo near the plunger (I have pictures if anyone is interested). So, even though I was purging my system with new fluid, it was contiually being contaminated.

Finally, I will resort to bleeding the system out again. If this fails, the hose to the slave cylinder will be the last part that I will replace.

Cheers!

OK, I took apart the hydraulic line and it is nothing like I thought. It is a teflon like hose enclosed by a braided steel sheath. So I didn't see anything wrong with this line. So a replacement is not necessary. I am still having clutch pedal problems... quite frustrating

**fbodynut** · 01-10-2008, 01:48 PM

hey menardst,
If you have replaced everything new, then it sounds like you just still have some air in the system. You really need to bleed the crap out of it. Two people... one on the pedal, and one downstairs getting brake fluid running down their arm.

I don't know your experience driving hyd clutch set ups, but what i have learned is that a hyd clutch feels nothing like the old school spring assist, z bar set up. I think driver comfort, ease of use became an issue on clutch cars.

**som1sc** · 02-04-2008, 08:11 PM

Hey guys, let me start by saying great write up. I have an 2001Z that the clutch pedal started sticking on. I have replaced the MC, slave and bled about 6 reservoirs of fluid through it. My pedal feels better than ever but still sticks. Only thing I didnt change was the braided line. I reused mine because it already had the drill mod. Clutch doesnt slip at all and the car only has 54,000 miles. Any suggestions

**fbodynut** · 02-05-2008, 03:26 PM

hey som1sc,
Didn't your mc come with a new line already attached?
Did you get a remanufactured by chance?
Does your pedal stick only during high rpm shifts? or all the time?

**som1sc** · 02-05-2008, 03:33 PM

The pedal only sticks at shifts above 4000rpms or so. Yes it came with a new line but I was doing the drill mod to it and my drill bit broke off and I ruined the line trying to get it out

It is a new GM master cylinder.

**fbodynut** · 02-06-2008, 03:21 PM

ahh, the plot thickens

Soooooooo if your slave is also a new non adjustable unit. Then my guess at this point would be that your old hose is either partly colasped/ blocked on the inside. Or........from your description of the pedal only sticking above 4000, your new slave is for whatever reason binding up. Did you clean the input shaft really well, check for damage/anything that might not allow the slave to operate freely on the shaft?

Is your slave a gm unit?

If jonb is still out there, any ideas???

**som1sc** · 02-07-2008, 06:18 PM

Same brand that was in it. Had the same part number. Another question for ya, does your quick connector coming from the slave wiggle a little bit ?

**fbodynut** · 02-08-2008, 04:06 AM

Yea, the hose will move a little. The more i think about the hose, it would seem to me if the hose was the culprit, then rpm shouldn't be a factor. You would think your pedal would stick at any rpm if the return path was blocked in the hose. Another thing, are you doing a hard/ fast shift lifting the pedal fast when the pedal sticks? Or just a normal shift. Try doing a fast pedal lift at a lower rpm and see if the pedal sticks there also. Then I would look at the hose, before I dropped the trans again.

Does that make since? Even if you still had air in the system somehow, rpm shouldn't change when the pedal sticks. Hey, I could be wrong!

When mine screwed up, I replaced the master, then went into it with the intention of replacing everything regardless. Because I did not want to be lying on my back pulling the trans more than once. I inspected every component, and did not see anything obvious jumping out at me. Which makes me want to agree with jonb's description of the slave binding up internally... At least in my case.

I don't know if I am helping any. All I can do is share what I have learned in dealing with mine.

**som1sc** · 02-13-2008, 06:37 PM

Sticks wether I shift it fast or slow at high rpms. I think Im just going to put a new clutch and flywheel in and go from there. Some say it could be the pressure plate. Who knows.

**fbodynut** · 02-14-2008, 03:29 PM

Hey, I bet there are a couple engineers at GM who probably know exactly what is causing this to happen in our cars. But if you go ahead and replace everything, then............ I know this doesn't solve the mystery, but it sure beats pulling the trans every time to replace one item at a time.
I looked close at all of my stuff when i pulled mine down and really did not see any major defects...like cracks, or broken parts...
Now if I had a rack in the ole garage, I would do exactly that just to see which piece is failing, cause I HATE just replacing parts with no clear evidence telling me to do so.
Good luck

**Kamesense** · 02-15-2008, 01:27 PM

Amazing write up! Great info, I just had this problem on my Z28 yesterday. I was wondering if the stock clutch was saying goodnight, but it seems ill be able to hold off on the LS7 clutch kit.

Oh btw, at around how much power should i be concerned with the stock clutch: 1999 Z28, M6, slp cold air, cat back, tuned, thermo