Clutch Problems

elhombre

Hey guys,

So I was driving my car back from a trip to Rhode Island when I got a strange feeling from my clutch pedal. The pedal didn't go to the floor but the first half of the stroke didn't disengage the clutch. I pumped the pedal a few times and it came back. About a half hour later I went to shift from 6th to 5th...there was no clutch there. I pulled off and pumped the clutch and was able to get my clutch to work, although the working range was right when the pedal got about an inch from the floor.

So I have my car on my lift and am inspecting it, there are no leaks from the bell housing. The fluid in my master cylinder is clear and clean looking. I am guessing it is either air in my lines (somehow) or a faulty CMC. I am swayed this way just because my clutch still works it just engages low and I haven't lost any fluid/seen contamination of the fluid from clutch dust.

Anyways, some input into the situation would be great before. BTW the car only has 32k miles on it...

Jsolo

I agree with your diagnosis. If the level in the reservoir isn't low then it's either air or the master is failing.

Cheap immediate option is to flush the fluid out to ensure no air is present. If it's been working fine for 32K miles then all of a sudden this happens, I'd say this fix likely won't do much and a new mc will be needed. When was the last time fluid was changed?

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G37S Sedan 6MT, Eibach swaybars, Invidia Exhaust, Weaker Clutch Pedal Spring

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JARblue

You're on the right track. If the fluid is truly clean (i.e. replaced recently), then its probably your master

Luckily it's a pretty easy DIY fix and cheap if you pay someone. Options are a straight OEM replacement (~$100), a rebuild kit (~$18), or the new RJM heavy duty master (~$300).

I just recently installed the RJM master for piece of mind. I had to replace my OEM master 3 times before the RJM master was even available.

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elhombre

Goin to look into it now...

elhombre

Well it was just some air caught in the line. It took a while to bleed it out, but the clutch feels good. For now...I may just buy the RJM brake pedal though, its supposed to reduce CSC wear which is a problem on our cars.

JARblue

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nis350

Just curious how the air got in? air shouldn't get in the system if it is working/sealing properly. the seal maybe on its way out.

did you have some work done recently?

elhombre

I just bought the car 6 months ago, the clutch was completely fine until the heat came. Then this happened.

I also just had the clutch go out on me again, with no leakage and a full reservoir. I more than likely left some air in there when I bled the clutch, possibly from frothing the fluid by pumping the clutch too quickly.

After I last bled the system I let the car sit for a weekend (went on vacation) and when I came back the pedal was soft but after 2 full strokes it was hard again and had a full stroke for 504 miles exactly before I again experienced my clutch go out.

I am going to back bleed the system and see what happens, if this doesn't work then I will re-check the master cylinder. If the slave cylinder was gone it would be leaking, or at least would have produced dirty clutch fluid immediately.

ban25

Though it shouldn't be an issue for street driving, the clutch hose is uninsulated and runs straight past the exhaust, causing the fluid to boil easily with aggressive driving. It might be a good idea to flush with some high temp fluid, like Motul RBF 600.

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2017 Corvette Z06 7MT | 1LE | Stage 3 | DSCSport

elhombre

I will hopefully be able to get to it tonight. I have replaced the old fluid with RBF 600 when I flushed and bled the system last week.

elhombre

Well I back bled the system (harbor freight oil can and a syringe) and the system pressure has been restored to its former glory.

The traditional method for bleeding this clutch system is tricky to do correctly, especially when there is air caught. I would recommend back bleeding the clutch system to ensure proper function after the procedure.

ban25

IIRC, there's a T-junction in there that makes it a real pain...glad you got it sorted out!

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2017 Corvette Z06 7MT | 1LE | Stage 3 | DSCSport

Jsolo

Can you elaborate on this?

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G37S Sedan 6MT, Eibach swaybars, Invidia Exhaust, Weaker Clutch Pedal Spring

For sale links

elhombre

Well now 300 miles later and fluid reservoir is empty and inconsistent brake pedal pressure...

Spooler

CSC is done. Get a Master also since you ran it dry on fluid.