Here is the story, a couple of years ago, I replaced the clutch with a new along with a aluminum flywheel. Hydraulics were fine at the time. but I noticed the clutch grabbed different after the install, I thought it might have been a difference between the lighter flywheel and the heavier one it replaced. The car seemed to shift fine.

Last year I noticed difficulty shifting into reverse, so I replaced the Slave cylinder (changed to 91 style).. it did not help, but the slave I got was bad and leaking.. I swapped the slave again, followed ZFDOC's instructions to bleed it, drove it a couple of weeks then put it away. at this point I also knew I needed a clutch (smoked it at the track).

Now I have a new clutch, put the car back together but noticed the clutch was grabbing close to the floor (1-2" off) and it was hard to go into 1st and reverse. I swapped out the Master since the slave was fairly new, First Master was bad, the current Master seems fine, no leaks and working the way it should. I Bled it ZFDOC's way and it did not get any better.. then I followed the GM Manual and bled it again. Seemed fine..

Drove it to test it ( maybe 2 miles) seems to shift into reverse and 1st a bit easier but the clutch still grabs quite low (2" from floor).

Now I have searched the site and found that the Fork could be bent or bad, but is there a way to check? I also have ordered an 89 Slave to try to get working better then the 91, I am tired of throwing money at the car. I am suppose to go Drag Racing ont he 13th with my local club ( I am running the event so I have to go) but it looks like my vette will not which sucks unless I can get the issue worked out.

So, How do I check the fork? Any other things I can try? and what is the typical grabbing point from the floor? This is grabbing lower then I think it should.. I am out of ideas..

 

I wish I had an answer for you! I'm a rookie C4 owner & I'm kind of going thru the same with my 90 ZR-1. OE master leaked thru into foot well. I noticed loss of fluid & grinding noise sometimes when I stepped on clutch &/or moved gear shift. No trouble going into reverse though, just 1st & 3rd sometimes. Dealer said just do master...I said do hose, master & slave please...they said not necessary. I put in all three, no diff on grinding, still intermittant. I changed three sets of master and slave & have not got a good set yet, two sets from chevy dealer and one set from auto parts store. Last two times after install & bleed w/phoenix injector I get rubber particles in fluid in master after test drive. I had been told that there is a run of bad bores in either slaves or masters or both?? I initially contacted zfdoc & he said to also check the pivot stud for the fork, it might be loose. After latest install I got very low clutch grab also??? Very strange but it came up eventually when I shut down and re-blead the system? Very strange indeed. You might want to check the clutch pedel arm. At the ZR1Registry site there is a report of that getting bent and the result is reduced travel on the pedel. Looks like you tried everything else, it might be worth a look.

Good luck!

Tom

 

Hi Jeff!

Something is definitely wrong if it's grabbing that low. I've been through 3 Master/Slave cylinders in as many years and the only time the clutch grabs that low is when there is air in the line. It should engage near the top 1/3 of the pedal travel and you should feel the resistance as soon as you touch the pedal.

Never had a problem with the fork...sorry that I can't help you there.

Joe

 

Well then I still have air in it. I am going to follow the GM Service manual to bleed it, I also have an 89 Slave on Order (one source claims to have it). I don't get the resistance like I should though. I was using a Mity Vac to bleed it, but I don't think that works the best. So i will get my Father in law to operate the pedal while I bleed it.. That way you are pushing fluid out instead of trying to suck it out.

 

Do a reverse bleed & get her a*s*s up as high as you can so the air will travel uphill to the tube & out the clutch master.

 

Been there done that 4 times.. Found out tonight that it looks like the master I got is bad..

Oh well

 

How did you diagnose that?

 

Pedal travel was not the full amount it was when the system was good.

 

Sorry about jumping into your thread Jeff. I apologize for sounding like a lunitic.:o

Is the fluid dark with rubber or black particles? Reason I ask is that after the last two slave cylinders I replaced the fluid turned black. I took them apart last night and found metal shards or small jagged chunks and some slivers behind the piston seal. One seal was chewed up bad at the ridges. The next slave cylinder I took apart had a fairly large chunk of jagged metal & no slivers behind the piston ( at the end of the cylinder where the spring is) and the seal had just one big nick in it. Both slaves I bought from a chevy dealer. I also took apart both of the masters that went into the car with those new slaves and only found rubber particles. Also I noticed that the bores on those slaves were fairly marked up parallel to the direction the piston travels, one slave also had dark spots on the bore and both had a few fine scratches that are perpendicular to the piston's travel direction but way at the pushrod end of the bore. I also noticed that the spring for the piston had jagged ends to it and that the mfg grinds the ends so they are flat instead of round. The grinding leaves the flat ends' finish very coarse like 60 grit paper and the end of the spring very thin.

Again I apologize for ranting in your thread! I'm usually not like that but this has been going on with my clutch hyd sys thru three sets of masters and slaves plus two hoses. I'm just baffled by all this bad luck I've had. I'm ordering another set and I'm taking them apart before they go in the car to look for foreign material. Also, the last slave I bought was from Raybestos, and the slave looks exactly like the ones I bought thru the chevy dealer. The master was from Wagoner and looks different from the OEM part. I'm guessing that one of those companies make them for GM.
Good luck with your problem!

Tom

 

Tom,

there were no particles and the fluid was not black.

I too had a Wagner part (1st replacement) it would not allow fluid out of the Reservior back into the line. this second one looks just like the OEM GM (CARQUEST) and is the same mfg. I am going to try to returnt he one to Carquest, bought it last Friday. I also have another new slave on Order from Advance Auto (PArtsamerica.com) As for the Master, I htink I decided last night that I am going to buy the Mcleod aftermarket piece. I found some guys on here using it with there twin disc and I think one with a regular clutch. I am at the point where I would like a quality part that WORKS!! this is crazy that I have to get 2 or 3 or more Masters or Slaves to get the clutch right. ame thing with my Brakes, I had my Master internally leaking, Bought a NEW one to find it was the SAME problem. Bought a F-body Master from a 98 car USED for $20 and it works PERFECT.. all I needed was a 3/16" spacer for the f-body master.

The Mcleod piece I ordered from Summit, it will not be here for another week, but I don't need the aggravation of not knowing if that master will work. the Mcleod is pricy but it is rebuildable.. hopefully it will work form me.

 

Thanks Jeff for being tolerant of me!

One of the senior members of the ZR1 net just told me about Mcleod. I am gonna go see what they sell. For my part I'm at the point that I've given too much cash to GM's suppliers and have not received any value in return. Whatever Mcleod's parts cost it has to be less than the cost of a rebuild by Mr. B! I will go check out summit and see what they have because the slave and masters for all the zf6 vettes are the same. Onlt difference was the early slaves had the bleeder at 11 o'clock and those bleeders hit the floor. The later, 91 & up, slaves had the bleeder re-positioned to 6 o'clock so as not to hit the floor.

Thanks for the heads up!


Tom

 

Do a search on this forum for the Mcleod PN from Summit..

I don't have the Pn but the unit is $336.xx

I am returning the Unit i got from Carquest last week tonight

 

Don't know much about the '89 so if may question is stupid bare with me. You mentioned you changed to an aluminum flywheel. Could this have something to with your problem. I switched from the Dual Mass to single mass on my '96 and that switch required me to either shave my disk or buy the shorter pivot ball that I believe TPIS was selling. I bought the pivot ball which makes everything line up. Could your problem be similar?

zzzasy
'96 lt4

 

I don't think it sohould be an issue. When I did the Manual swap into my car, I used the Centerforce SMF and it is the same thickness as the Aluminum one. One thing I noticed last night is that the Pedal was not going bakc to the proper resting location, this would be caused by the Master, Once disconnected the pedal traveled correctly.

If I have some time, I might try my Old Master in the car to see what happens for pedal travel

 

Dumb question, but I was wondering if you guys that used 2 and 3 different sets return them for refunds?

Jeff, I understood the 89's slave was discontinued, let us know if your source has some on a shelf somewhere.

I had to use the newer slave(why the heck did GM put the bleeder there?) and the newer hose(the steel braided covered one).
So far it's all OK.

 

Yes, I returned the first one back to Advance where I got it, received a refund.
Tried to return the second one to Carquest, unable to since it was installed but can exchange it. I am getting a new one from them tomorrow (no cost) I will probably cancelt he order for the Mcleod next week.

As for the slave I will know tomorrow if it is a true 89 style slave, then I will let you guys know ( I will reply in this thread)

the Car Quest one has a Lifetime warranty so I may as well try to get that one to work.

 

The best info I have been able to find out is that the 91-96 slave super ceeded the early slaves due to the fact that the bleeder had to be broken off or it would hit the floor. That's what I learned over at thr ZR-1 netRegistry, and as all the 6spds were zf6's they all use the same hydraulics according to GM parts listings.

As to the refund Q, I used/installed all the sets so I was out of luck, or so I was told. It seemed a bit unfair but since I'm just a backyard hack I could see the logic from the seller's point of view. I'm not a professional mechanic and who knows what I could have done to the stuff to cause the failures...but after three sets I'm gonna pull apart my next slave to look for the metal shards I found in the other two. I've yet to pull out the set I just put in last week but I'm sure I will find metal in the slave. How else would the fluid turn black after cycling the pedel? If my new one has a bad bore I will call rockauto.com & see what they might do...I'm not expecting much though.


Tom

 

Tom,

I bought a slave and Master from Carquest.. they will not allow my return the Master, but it is warrantied so i am getting a new one in exchange today. As for the Slave, I never installed it, I got a refund.

I bought a Master from Advance Auto (actually partsamerica.com) installed it, found it was defective, Returned it and got a refund.

I ordered my new slave (89 design) which has a different Part # from the 91-96 slave from the place I ordered it. I should have it today and see if it is the correct design. if so, I will post the source. I cancelled my order for the Mcleod piece yesterday after finding out that CARQUEST would not refund me for the master, just exchange it. If I have to get a new master every few days to get it right I will, Although I am now thining that it is my slave that is bad. Will hopefully know this weekend

 

Hey Jeff did your OEM slave have the bleeder at the 11 o'clock position? The 90 ZR-1's used that type of slave and on the line the bleeder screw had to be broken off flush or the end of it would hit the fiberglass floor, that's why GM had them changed for the 91 mod yr. They moved the bleeder to the 5-6 o'clock position which made it a PIA to bleed unless you had an injection bleeder.

I'd be all ears to see what you find in the box because I found at RockAuto a listing for a 90 slave that has a different P/N but I've no faith that it actually is a 90 slave. GM changed them and they only apply to C4's with zf6's so why would anyone bother to make anything but the 91-96 style slave. That's my logic for what it's worth. I bought a Phoenix injector so I could bleed my system so I don't much care where the bleeder is. I just want a slave without the optional metal shavings!


Tom

Disregard my dumb OEM slave Q. I see that you did an auto to zf6 conversion. More power to ya! You are more advanced than I. I would never attempt that.

 

YEs OEM Bleeder was ta the 11 O'Clock position. it is what I had in my car when I swapped..

I will let you know what I find, either way I will use the new slave.. BUT if it is the same as the 91, then I will complain cause it is more $$ then the 91 slave..

I will know tonight when I get home, Assuming it is at my door sometime today