Clutch pedal travels too low

[lfalzarano]

I had a hydraulic clutch failure. So far the master and slave clutch cylinders have been replaced. The clutch, pressure plate and throw out bearing were also replaced.

A road test revealed depressing the clutch pedal barely allowed me to shift into gear. The clutch pedal started to engage about an inch from the firewall.

What could be the source of the low level pedal engagement with the clutch? The re-bleeding of the clutch hydraulics provided no change in the clutch pedal engagement.

Ideas?


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[-=Jeff=-]

what brand/type Master and Slave? are you sure they are good? (even though they are new)

[lfalzarano]

89-1996 clutch master cylinder from Corvette America. It doesn?t say the maker. They listed as their brand.

On the slave cylinder GM parts bought one that was exactly like the one they removed. No idea of the brand.

I suspect either one is letting air into the system. I can?t be the thickness of the rug hindering engagement. The rugs have been around for many years.


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[Shizap]

What clutch disk did you install? If it's not the hydraulics, it could be a matter of needing to shim the pressure plate if the clutch disk is too thick. Marc Haibeck has an article that talks about Centerforce clutch disks and the recommended amount to shim them.

[lfalzarano]

What clutch disk did you install? If it's not the hydraulics, it could be a matter of needing to shim the pressure plate if the clutch disk is too thick. Marc Haibeck has an article that talks about Centerforce clutch disks and the recommended amount to shim them.



Thanks for the tip. I have forwarded the article to the service manager at the Chevy dealership.

The clutch kit and clutch slave cylinder was purchased by the the Chevy parts department. I?ve been feeding your suggestions to the service manager. He is in contact with GM support in trying to solve the pedal travel and hard shifting. I also asked Bill at ZFDoc for his thoughts.


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[Young1]

I have the best luck to reverse bleed the clutch hydraulics to get all the air out of the slave. Ask them if they did that. Simple things first.

[-=Jeff=-]

If you pump the clutch 50 times does the pedal get better?

[WARP TEN]

If you pump the clutch 50 times does the pedal get better?

No, but his leg gets worse....:cheers: --Bob

[-=Jeff=-]

My suggestion was based off of a slave cylinder issue from years ago. Bill B told me to try that. The system is self bleeding

[Matt B]

So maybe BOTH will happen [emoji3]

[Paul Workman]

I have the best luck to reverse bleed the clutch hydraulics to get all the air out of the slave. Ask them if they did that. Simple things first.

I'm not familair with the term "reverse bleed". What is that, zackly?

[Paul Workman]

I have bled the clutches on both the Zs by drawing fluid into the system via the slave cylinder -exercising and coordinating the bleeder valve and slave's pushrod to pull in fresh fluid and purge air out of the system. (It's VERY quick and IMO much more efficient than pumping the clutch pedal dozens of times (and I've done it both ways & would never return to the pedal pumping routine...unless I'm on my bicycle!))

[DRM500RUBYZR-1]

My suggestion was based off of a slave cylinder issue from years ago. Bill B told me to try that. The system is self bleeding

If 50 does not raise the pedal, do it more.
We gave up at 70 once, went back and did it again and finally got a pedal that worked.
If it is a new clutch, pressure plate, throw out bearing clutch slave and clutch master, then odds still favor an hydraulic issue.
Try 150.
I have to accept that a tech at a GM dealership installed the hardware correctly.
They don't let the lube tech do clutch installs.
Good luck and continue to keep us posted of your results.
:cheers:
Marty

[-=Jeff=-]

I'm not familair with the term "reverse bleed". What is that, zackly?

Pushing fluid up through the slave.. i have a Phoenix Injector for that task

[viper107]

revearse bleeding gets the trapped air out of the bends(thats where the air gets stuck and wont bleed out)

[Paul Workman]

Pushing fluid up through the slave.. i have a Phoenix Injector for that task

Yeah, thanx! And, in conjunction w/ the '91-95 slave (bleeder on the bottom) I see how that tool would really be nice to purge the system.

Got pix?

[lfalzarano]

Thanks Everyone! IT IS FIXED!!!!!
The solution was that when the mechanic replaced the origins clutch master cylinder, he left the original shims on the firewall. He removed the shims, installed the replacement, and bleed the system. The width of the shims were limiting the clutch master cylinder piston stroke!

Pedal feel is perfect and the shifts are smooth.

Thanks everyone for your suggestions that narrowed down the possibilities!


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