I'm having some trouble with my clutch as of late. It was not going in gear smoothly, so I checked the fluid level and it was low, added and everything was groovy...for about a week, now its back.

The problem is it dosn't seem the clutch is disengaging 100%, little stiff, and at stop liights from shifiting from nutral to 1st I get a slight forward push, only for the second I engage the gear, but with the clutch in, this should not happen.

Also in nutral with the clutch out I'm getting a bit of a howl.

My pedal is nice and firm as it should be, but I have the other problems. Slave? Air? Help?!

 

welcome to the world of ****ty clutch hydraulics... do a search, you will be astounded.

 

Oh I have, and I'm scared Bogus......I'm scared.

But I'm just wondering where to start looking.

 

slave.

 

Alright, I'll start by looking there.

I have no way of lifting the car to get to it, so I'm gonna have to take it somewhere, is there any place I can get a good slave? I've heard that tons of the seals are installed backwards on new ones.

Also, I was under the assumption if it was the slave my pedal wouldn't be firm?

 

well tomorrow I'm gonna top of the fluid again, and put down some big cardbord so I can see if there is a leak, and what area its coming from... wish me luck!

 

well I checked the fluid, it was no where near as low as before, when I checked last time it was at the bottom of the cup, this time it was at the fill mark.

I added some and went for a drive and everything felt great, any chance there was air in the lines that the fluid is now displacing?

 

sounds like there's some crud in the little hole that the fluid goes through to get to the piston cup in the clutch master cylinder, and a full reservoir adds fluid weight to allow it to flow through the obstruction. dark fluid is dark because the fluid is holding contaminants in suspension.
it's possible you also might have a worn piston cup in the master cylinder allowing it to bypass some fluid in the first 1/8th inch of movement, and or at full actuation, allowing your clutch to slowly re-engage even though your foot is still on the pedal, and it's on the floor. check out a clutch master cyl. rebuild kit
you probably have a little air in the slave cyl. or in the line also, and the extra bit of fluid in the cup helps it.
try bleeding the slave and refill the master, and see what happens.
btw, this will keep on happening until you find out what's leaking.
the reason the clutch master cylinder is small, is because there's not supposed to be any leaks, and you shouldn't add fluid to the system for years of normal driving.
even with evaporation, once a year at least.

 

thats great info! As I said in previous posts I don't have any way of lifting the car to work underneath it, so I'll call around this week and find somewhere to have the system bled correctly and see where I am after that.

The fluid in the cup was dark, and I never thought of an obstruction in that little hole, thats something that never would have clicked till you mentioned it.

Also, the symptoms you describe in the worn piston cup in the master is almost exactly what I'm experiencing. I was just automaticly thinking slave because of all the problems people have had with them in the past.

When I added fluid today I looked all around the master and saw no leaks, so when I find some place to take it in to have it bled they should be able to see if there are any leaks at the slave.

My current thoughts on it are: From the dirt level and tightness of the resivoir cap, it had never been removed or checked in my cars 10 years of service, thus the missing fluid when I first checked it (bottom of the cup)

And air had gotten into the system which the fluid I added displaced some of causing the low level I had this time (fill mark on cup)

So with my rationale, I'm thinking a good bleed may do the trick. I may be totally wrong though, so any more intel would be great.

Thanks again coupeguy!

 

You say you are having to add fluid to the master cylinder every once in a while and then the clutch appears to work fine. There is no noticable fluid leaking from the slave or master cylinders.

This is a classic case of a leaking seal around the shaft from the master cylinder that goes through the firewall. The fluid leaks out along the shaft and into the driver side compartment under the carpet unseen. That is why you have to add clutch fluid, yet see no leaks. Feel where the shaft comes through the firewall and see for yourself. You must have the master cylinder rebuilt or replaced.

Many shops recommend replacing the slave at the same time, but I say if the slave is ok, leave it alone. Too many slaves coming new from the factory with bad seals. Fix the master cylinder and refill with new fluid. Bleed the slave until it is full of new fluid and you should be good for many more years.

 

Alright, I'll check that tomorrow, where exactly should I look? Remove kick panel and pull down carpet? Or is there an easier way?

 

If you can stay outside the car with the door open and stick your arm up to where the top (pivot point) of the clutch pedal and feel the brkt, go towards the fire wall and get to the carpet. Peel the carpet back just a bit so you can touch the "insulation" under the carpet....if your fingers come back wet you have the "thru the wall leak". Sometimes if you get your head in the right position and the leak is bad enough you can see fluid on the push rod.

Good luck with this problem and be aware that there has not yet been an "official" GM soloution to this problem...or at least no announcement has been formally made about the TRW Q/C trouble and the soloution to that problem.

Bleeding the system is difficult if there are any worn parts because even thou you get all the air out you are still loosing hyd pressure due to worn seals in the M/C and or slave. Also, if you have a 91 or later OEM slave the bleeder is in the wrong spot for bleeding the system with the slave mounted on the bell housing...it must be disconned and made to hang upside down to orient the bleeder correctly. If you have a 89-90 OEM slave the bleeder was broken off at the factory because it would hit the floor pan....the bleeder was at the 11 o'clock position. Right for bleeding but not right for installing it in the car! I use a phoenix V12 injector but there are other ways to bleed the system.

You may want to go over to zfdoc.com and do some reading on the zf slave & master cylinders' problems. There is alot of useful info there on the "how to" aspects.


Tom

 

Alrighty, I havn't checked for the "thru the wall" leak as of yet, But I have a new development that might be useful to the guru's.

After filling the resivoir, and pushing the clutch, I'm getting a squeeky noise from the master, sounds like a seal, dunno if its normal, but I thought it to be usefull to add this info.

 

Usually, according to zfdoc.com, the cause is using regular brake (DOT3) fluid. It doesn't have the same "friction modifier" package that genuine GM Hydraulic clutch fluid has.

I know when I used DOT3 instead of the GM H C F when I was chasing my problems I got the squeaking.

it works either way but the GM/ HCF = no squeaks.

There is another way less likely cause for squeaking. When the M/C piston rocks in the bore, the piston hits or scrapes the bore and sometimes makes squeaking noises. One of my "bad" M/C's did that. The reason that the piston "rocks" in the bore, according to zfdoc.com, is that the OEM spacer is not the correct angle and the push rod deflects and is no longer centered on the piston.


Tom

 

I bet thats it, when I've been adding lately I've just been using DOT3...I'm glad thats easy..but I was kind of hoping it pointed to the problem hehe.

 

UPDATE:

Clutch started acting up again, checked the fluid, not 1 drop low.

It is bleeding down when I hold it in for more than about 10 seconds, I can hear the clutch engage a little, not enough to lower the RPM or move the car, but I can indeed hear it, VS. when I just mash the clutch quickly and it goes quiet.

Master cup seal? Still possibly slave?

 

Not a good sign! It might get worse, mine always did when those symptoms started out slight. I always seemed to be unlucky and they got worse.

The cause could be either part....I know that's not what you want to hear! I'm not trying to be a b breaker or trying to be funny. I could never get lucky and figure which one was at fault. Seems I'd change a slave and it would not fix it. Sometimes I'd guess it's the master and it wouldn't fix it. I got so frustrated after awhile I started to change them in matched sets!

I ended up with quite a collection of bad parts!

 

oh dear.

Alrighty, should I just say to hell with it and replace both the master and slave right now to save future heartache?

How many did you have to change total? Is it fixed now?

I'm scared Tom...

 

M, I'm not gonna tell you what to do....I'm not a Tech, just a backyard hack!

This is what I went thru. I'll try to be brief. I'm giving you this so you can make a judgement call.
Car type:90 ZR-1 same trans as any other 6spd C4 save for the input shaft collar & bellhousing, same hydraulic parts! 12/04 my new used car arrives w/8200 miles on it. 7/05 @ about 11K miles my master leaks. All hyd parts are OEM/from BG. I change out leaking master(thru the wall leak). I'm having trouble as the local dealer says the slave & hose are NLA. I take the new M/C & install same. I check myself & find old slave & hose superceeded by 91 thru 96 slave & hose. Clutch works, but not great, at this point but as per instructions @ zfdoc never just do one part of sys. Not his fault as I believe that his advice is correct! So I order new slave & hose, OEM/dealership parts. I put them in & feel great. A week later grinding, 2nd gear syncro dogs, going into 2nd. At this point I think I'm a dunce, can't even swap parts & bleed a simple hyd sys!

I buy more parts from dealer, slave & M/C & hose & six bottles of GM/HCFluid. Put them in & still same if not worse. I buy another set slave & M/C. Bench bleed M/C & slave(I have extra parts!) before install. Still same symptom. I buy pheonix V-12 bleeder & re-bleed system, still same. I buy amother set from dealer & repeat entire process, results still same or worse...one set failed asa I stepped on clutch to get reverse! I post in my regisrty & everyone thinks I just don't get it. Only Bill Boudreau says "ya got deffective parts" & explains what he has been fighting since 03!

Now: 4/06 or there abouts -=Jeff=- and others post up about basically same symptoms and problems r & r'ing clutch hydrulic system. We all compare notes & learn seal in slave is backwards & DOM/OEM style parts have other defects! Dealer says " your throw out bearing is n/g." Bill B says "tell the dealer to get a clue!" I learn from jeff about cast style M/C's & slaves. Also, by this time Bill gets some one @ chevy to listen about the parts, GM calls in TRW(the contractor for the parts) and says they will ask TRW "what's up!". Still no word on that situation. Also, by now, 5/06, parts are getting hard to come by...either OEM/dealer stock and auto parts stores. I buy a cast slave made by Fedral-Mogul sold under the PBR brand. It will not fit on my bell housing studs & leave enough threads for me to feel good about it. I install a new cast (wagner) M/C and take my best DOM/OEM style slave body and I gut the slave of it's internal parts. I gut the cast F/M slave and transplant those parts, spring + piston & seal + pushrod, into my best DOM slave body. Bleed the system & it works, at least up to now(praying) for at least a few thou miles.

Why did it work? Not sure honestly but the F/M seal is different from the DOM/OEM style seal....it has no micro-ridges to tear. If those ridges get nicked, even a bit, the slave will not hold pressure. The F/M seal looks more like a mushroom & has more smooth sealing surface and it's a bit fatter & fits tighter in the DOM style slave's bore. Bill, zfdoc, will flip the seal in a new DOM style slave for a fee, he knows how to do it without nicking the micro-ridges on the way out & going back in! All my DOM seals had varying degrees of nicks on the ridges & I'm sure I did that & that's why I couldn't get the system to work.

Sorry I wrote a novel anyway! But this isn't easy to explain by typing!


Tom

 

Well, today was the Ultimate Corvette Party (400 vettes) and last night my clutch was once again feeling chunky.

I got the GM clutch fluid and popped the cap, and it wasn't a drop low again!

I'm really starting to think its the slave, from what I've been reading on zfdoc, with the description they give for the symptoms of the improperly installed slave seal are the same things I'm experiencing.

NOW! I believe you when you say you should replace all 3 parts, it makes sence (to me..not me wallet heh) How hard is it to replace the hose? ?I have no idea where the hell it even runs!

Also, I'm experiencing some howl in nutral with the clutch let out (thats how I know mine is bleeding down and not fully disengaging heh)

I'm thinking throwout bearing, but I'd like to get your opinion.

Could that be causing my other problems? How would I replace it?

Sorry for so many questions, I'm still new to working on manual trannys.

Thanks!

Rich