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

[alwayscode390]

I have noticed my clutch lets out really high up , almost where the pedal is fully disengaged (maybe an inch from the top).

Is this typical for our systems?

The clutch on my Viper engages really low , about an inch off the floor (opposite of the ZR-1).

I wasn't sure if this may be a clue that I am about ready for a new clutch? I don't notice it slipping at all , so it may be normal ... but I was just curious enough to ask you guys.

The car has 44k miles on it , and got the LPE topend package installed at 23k miles ... so not sure if its the original still or not.

I tend to get the loud transmission sound after everything is warmed up too. I think my flywheel weights are flopping around if its even the dual mass anymore.

If it is time for a clutch and flywheel replacement, whats everyones favorite aftermarket combination to look into?

Thanks! :) ---

[GOLDCYLON]

Mines always high

[alwayscode390]

OK, that's great news, thanks Goldcylon! :) ---

[Kevin]

very high but Marc Haibeck told me that means I need to replace the clutch

[alwayscode390]

Ive never ran a clutch out until it failed before.

Whats the worst that can happen , it locks you out of shifting?

What kind of damage can happen?

Isnt there a way to test if you are slipping or not by putting it in 4th gear at a low rpm, then giving it a good amount of throttle (then watch if the RPMs rise too quickly)? ---

[Bearly Flying]

Mine is very high also and the clutch in it does not have much feel to it, it's either engaged or not...Makes stop and go driving a Royal pain in the Butt.

Previous Owner had an Aluminum flywheel and Heavy duty clutch of unknown origin installed, I'm going to try changing it out for a more Street Friendly version.

[We Gone]

My 91 is just past mid way with new clutch & PP Marc just installed it. The 93 is about the same with 26k miles.

[scottfab]

Mine is midway between all the way up and to the floor.

[FU]

Whats the worst that can happen , it locks you out of shifting?

What kind of damage can happen?


Transmission syncro's.

[alwayscode390]

That's if you try to force it into gear though, right? ---

[Z06scentair]

That's if you try to force it into gear though, right? ---

You don't want the clutch to come apart period. It could cause all kinds of concern for your underpants!

That being said, mine lets out around middle of travel.

[alwayscode390]

Usually it would be pretty obvious that there are issues though, its not something that just happens overnight ... right?

First thing to notice would be grinding gears easier? ---

[TheBlackPearl]

Mine engages at about 1/2 to 5/8 of pedal travel from the floor. I believe it used to be higher until I changed the clutch fluid.

[csavaglio]

I slipping clutch isn't engaging. You won't notice grinding. If your hydraulics are going, they won't fully disengage the clutch, so that's when you get grinding. You can test for slippage by driving about ten MPH, put it in 5th and floor it. If it builds rpm slowly, its ok. If it slips, it'll build rpm faster as though you're revving it with the clutch pedal half engaged.

The best thing to do is talk to Jim at Power Torque Systems it the ZF Doctor.

[alwayscode390]

OK, well the last few times I drove the car I noticed it was hard to get it into reverse ... almost taking two hands.

It seems to be intermittant, but I have been missing 3rd ... almost like its locking me out or notchy to go into gear , taking more force than it used to.

This is the kicker ... now my pedal seems to be engaging almost to the floor, like the complete opposite as before. I hear a slight click sound also when the pedal is let out about 1/2".

There is no clutch smell, the fluid under the hood looks good, and there is no slipping under load in a high gear.

I am thinking I have a clutch linkage adjustment necessary? Maybe a lock nut is loose?

Thanks for your suggestions! ---

[nelson007]

My 93 and 95 are both midway. My 2012 ZR1 is about the same as your Viper.

Nelson007




I have noticed my clutch lets out really high up , almost where the pedal is fully disengaged (maybe an inch from the top).

Is this typical for our systems?

The clutch on my Viper engages really low , about an inch off the floor (opposite of the ZR-1).

I wasn't sure if this may be a clue that I am about ready for a new clutch? I don't notice it slipping at all , so it may be normal ... but I was just curious enough to ask you guys.

The car has 44k miles on it , and got the LPE topend package installed at 23k miles ... so not sure if its the original still or not.

I tend to get the loud transmission sound after everything is warmed up too. I think my flywheel weights are flopping around if its even the dual mass anymore.

If it is time for a clutch and flywheel replacement, whats everyones favorite aftermarket combination to look into?

Thanks! :) ---

[mike100]

OK, well the last few times I drove the car I noticed it was hard to get it into reverse ... almost taking two hands.

I am thinking I have a clutch linkage adjustment necessary? Maybe a lock nut is loose?
---

Is your clutch hydraulic fluid topped off and bled?, outside of the throw-out bearing fork, there isn't any mechanical geometry to it outside of the clutch disc thickness. I would bleed it. a bad clutch would still release and it should never be hard to select a gear.

[alwayscode390]

Not sure if its bled or not , but its topped off and clean looking.

It may have air in it ... the guy who owned it before me posted on here that his kid drove the car one night and came home with NO fluid in the reservoir. Not sure how he fixed it or what he ended up doing in that situation though.

The thing that kills me is the car has driven fine for the past 2 years I have owned it ... its just this past month the clutch is acting funny.

Thanks for pointing out a possible issue ---

[alwayscode390]

I read up on Bill's ZFDOC site , and I am starting to think I am having clutch hydraulic master issues.

He says " The preemptive dog teeth are most susceptible to damage when the clutch hydraulic system becomes degraded. The sensation of NOTCH SHIFTING is more prevalent when the sliding collar's preemptive dogteeth become worn or badly deformed. Advanced stages of preemptive dog tooth wear may result in GEAR ENGAGEMENT DIFFICULTY due to metal burrs restricting normal movement of the sliding collar. A healthy clutch hydraulic system should provide silk-smooth gear engagement. "

I just hope I caught it in time before any kind of damage has happened.

How many hours is a clutch replacement? How about the time for the clutch master cylinder replacement?

As far as trying to bleed the system first, I have never done that before ... what is the process? THANKS!!! ---

EDIT : I just emailed Jim at PowerTorque too ---

[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/2007/01/clutch-hydraulics-on-the-1984-to-1996-corvette/ "

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

[Dynomite]

"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/2007/01/clutch-hydraulics-on-the-1984-to-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) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-4.html#post1581644913)

[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 :-D 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.

[alwayscode390]

Thanks Mike!

I cant wait to see your writeup and how noisy you think the setup is ... that's a slight concern of mine. :) ---

[5ABI VT]

Thanks Mike!

I cant wait to see your writeup and how noisy you think the setup is ... that's a slight concern of mine. :) ---

Its a totally different setup on my 93.. its a McLeod twin disk with aluminum fw and the solid roller valvetrain plus exhaust with no cats all make quite the orchestra so it drowns out the rattle. Might be able top hear the high pitched tick when you get to the drivers door here
https://www.youtube.com/watch?v=sx8ZUoPZRDc&list=UUIL5e6oRCjClqBSS3W_p1ug


personally im Very tolerant. I don't really care if the rattle is very loud. Just knowing that much weight was removed is enough to make me happy. Im trying to make my car more raw.. more response.. more power, sharper handling etc etc. To me the factory c4 is a grand touring sporty Cadillac and that give me a perfect platform to modify.:) I will definitely post videos to hear what it sounds like afterwards.

[alwayscode390]

You guys are great!

I got a chance today to check the clutch master cylinder and it was BONE DRY!!!

Filled it , pumped the clutch a few times and I could feel the pressure get back to normal.

Drove it around the block and smooth as butter again! Grabs up at the end of the pedal again instead of right at the floor.

Thank you all so much, I will be ordering the replacement master and slave tonight :) ---

[alwayscode390]

Im honestly surprised people say "just keep refilling it if its leaking".

Isnt brake fluid flammable?

Has anyone heard of a car catching fire from a leaky hydraulic setup or does most of the fluid leak on the drivers side carpet?

I guess the exhaust manifolds are a good foot from the hydraulics ... and most leaks are drips , not a spray ... right?

Just curious, thanks! ---

[LGAFF]

not that much fluid in there...usually it either is soaking your carpet pad if the master is failing or coating the inside of the bell housing.....if there is enough you might get a few drips from the inspection cover