Where does your clutch engage on the pedal? High or low? ---

[Dynomite]

Originally Posted by alwayscode390

"Try to put it into reverse when it first gets started.
If you have difficulty getting into reverse there’s a very good chance that the clutch master cylinder is not at 100%."

This was a good page too : " http://tech.corvettecentral.com/2007...1996-corvette/ "

It says to replace the slave and master at the same time. Looks like that is where I will be starting ! ---

See item #3 Low Mileage ZR-1 Restoration (Audio, Injectors, Starter, Clutch Hydraulics)

[mike100]

I think the failure rate of the slave cylinder is many times higher than the master. I slapped on a $50 parts store slave (the ugly cast iron body type replacement) and it has been working fine for the last 3 years.

On one of the polls about 'What has failed on your ZR-1', the slave cylinder was right up there with injectors as the most common problem.

[alwayscode390]

Thanks Mike, I found a cast iron replacement made from a company called Sachs that I was going to try for around $80.

Dynomite, awesome info.

" The Clutch Pedal was SOFT indicating low Clutch Fluid and it was difficult to shift the ZF 6-40 Transmission into various gears including reverse.

Typically the Clutch Fluid Reservoir Fluid Level is not maintaned on low mileage ZR-1s simply because the Clutch Fluid Reservoir cannot be found. The Clutch Fluid Reservoir is located under the ECM (disconnect the two 10mm nuts and swing the ECM upside down to locate the Clutch Fluid Reservoir. Clean the Reservoir of old Brake Fluid and fill full indication with DOT 4 Brake Fluid. Pump the Clutch Pedal many times slowly self bleading the air from the Clutch lines. The Clutch Pedal will become a bit harder to push from the initial depression all the way down indicating the Clutch is being fully released. This will allow easy shifting of the ZF 6 -40 Transmission in all gears including reverse. "

As you mentioned, I never realized this so it may be low! Can it be seen without disconnecting the ECM? I cant get to the car right now or I would just try to find it.

Thanks! ---

[mike100]

you should be able to get at it with a long funnel. You could also loosen the two 10mm nuts on the ecm bracket to flop the ecm to the side without unplugging anything if it would make it easier.

i have a dedicated garage turkey baster that i just use for brake fluid. Use one to suck out any remaining old fluid, then top off with new brake fluid and have a helper pump the pedal while the person underneath attempts to open the bleeder screw. If the system is still partially primed, you can easily bleed new fluid and purge any air bubble. putting on a new unit is another story.

you may be able to revive the function of the old unit, but it will leak out in a short time and the problem will come back...but that can get you back on the road for the short term.

[alwayscode390]

WOW, this is embarrassing , but atleast I am learning!

Mike I thought one of the brake master cylinder reservoirs was for the clutch like it has been on my T-56 equipped cars! DOH!

I didn't realize one was for the rear brakes, and one for the front brakes!

I bet we just pinpointed my problem. Thank you all so much! I will see if I can fix/mend the issue like you mentioned , but will order new hydraulic units for a real fix in the near future. ---


EDIT: I just searched the old owners posts on here and 3 years ago he said the Master was dry one day ... and he was going to replace both units , but someone (on here) talked him into just refilling it. I'm sure its just low again. ---

[alwayscode390]

When you pump the pedal to "self bleed" its safe to leave the cap off the clutch master? It wont squirt fluid everywhere like if you do that on a brake master?

Synthetic DOT 3 brake fluid is fine for the refill on the old unit until I get the new stuff installed , then use the GM hydraulic fluid ... right?



Thanks! ---

[mike100]

I used regular a $4 can of regular DOT3 brake fluid for mine. To be honest I never even looked up the spec. You just want clean, moisture free fluid to move the rod back and forth. I'm not even sure it gets as hot as brake fluid, although it is in close proximity to exhaust pipes. No problems for the last 3 years.

I did put the cap back on. had a helper push clutch pedal to half way point and hold while the bleeder screw was cracked. It won't take but a few bleed cycles- the air, if any, comes out mostly on the first cycle.

[mike100]

Putting a new, dry cylinder on is a bear. My best method was to attach a hose to the open bleeder nipple, push the actuator rod all the way in, then put the hose in the bottle of fluid and let it suck in fluid as the spring pressure on the rod expanded the cylinder back to fully extended. then it is 95% full of fluid. you can gravity bleed the master and feed line. quickly connect the dripping feed line to the new slave cylinder and it will stroke well enough to bleed normally. Don't go putting it on full of air, you'll never get enough action on it to get any pressure build up on the pedal.

[alwayscode390]

OK , sounds like a plan!

The bleeder screw is on the slave cylinder, right?

I got a response from Jim at PowerTorque and hes sure its the hydraulics too. He also let me know the clutch pedal is NOT adjustable ---

[5ABI VT]

I have never done any clutch work on any cars.. but I just picked up a trans jack today.. and Im ready to go on my clutch/flywheel at home. Ill be making a thread and posting pictures along the way very soon. My clutch engages very high.. but it holds and grips perfectly. When I pull it out Ill know how much life is left. My gut feeling tells me there will be lots of it. I feel bad pulling a good working system with a perfectly silent dual mass isn't good but the idea of dropping 25+ lbs off the flywheel is making me drool Having said that.. it definitely sounds hydraulic to me. I have a twin disk in my 93 and the first 4 masters they sent all had leaking masters. I got caught out a few times as the fluid almost completely leaked out and the symptoms were similar to yours.