et1199

Just went and checked and you are right. I am on the way out the door to buy the necessary stuff for the protocol. Hope it works...and thank you.

u4ick

Another question.
Most of us here reporting sounds like these issues are during Drag/Street racing type conditions.........ie: hard strait line acceleration.
Question is, are those that do the road course type racing, with lots of shifting and high RPM use, are they experiencing this issue as well?

Ranger

Serious racers supported by crews preempt the issue altogether by changing the clutch fluid along with the brake fluid, so I was told by the SSCA race team crew chief.

Ranger

Warp Factor

Did Ranger's routine a few days ago.
Five passes today at Norwalk, 500 rwhp on a stock LS1 clutch. Pedal was slightly low after one pass, but that's as bad as it got.
Regular street tires though, couldn't use full throttle till third gear, probably made things easier on the clutch.

u4ick

Yes, but I'm refering to the weekend warriors................those that go out once in a while.

ptindall

Yes, while on the track was the only time I had the pedal stick. And it always feels lower and softer while I am racing. Frequent fluid changes and better heel and toeing have kept my pedal from sticking, but it is still low and soft. My car has 116,000 miles on the original clutch and the fluid looked like ink when I got the car. I change it whenever I think of it, not as often as I should, and it never stays perfectly clear, but a lot better than it use to. I am only making 350rwhp/ 350rwtq.

BobbyG

Ranger,

It's because of knowledgeable folks like you that Corvette owners like me have few problems with their cars. I've read, and even printed out, your instructions and performed these services on my Z06. They've become part of my routine maintenance plan thus eliminating some of the problems that others have...

I'd like to personally thank you for spending the time sharing your knowledge and experience with the members of the Corvette Forum.

Ranger

Thanks for your kind words, BobbyG.

Sometimes it takes a lot of posts on a practicular approach to a problem before the validity of the solution is generally accepted. And often it initially meets fierce resistance. Inevitably though, correct approaches become standard as more and more owners verify them through their own experience. Clean clutch fluid is a good example of this.

What motivates me on this issue is a hope of sparing others the month-long misery I had with the clutch in my 01 Z06.
(1) sticking pedal
(2) then clutch replacement under warranty to cure it
(3) botched install first clutch, fierce vibration
(4) botched install of immediate replacement, fierce vibration
(5) botched install of 2d replacement, fierce vibration
(6) rebalance of motor by Chevy field engineers
(7) pedal began sticking again soon thereafter
(8) I bled the slave fully and repeatedly with DOT4 fluid. Yielded normal pedal thereafter.
(9) kept the clutch fluid clean from that point on through six year and many passes. Normal pedal.

So my approach, clean clutch fluid, is a bitterly learned lesson. And one I am particularly committed to sharing. It works and can spare others my bitter experience.

Ranger

mqqn

Hi Ranger -

I have been able to mitigate my mushy clutch syndrome by keeping the fluid clean and clear as per your suggestion.

I might suggest that if someone has not been able to relieve the issue using the fluid-fresh method that you prescribe, then they either are not follwing the directions properly, or they have a more serious issue with the clutch.

best regards -

mqqn

Tech

Do Corvettes not have the fluid restrictor in the hose coming off the master? F-cars have the same problem and opening up that restrictor with a drill bit fixes the problem.

Ranger

No one has reported clutch behavior improvement by the "drill mod" in a C5/C6.

In 2002/2003 several vendor released modded hydraulic lines that had been drilled. They were purchased and installed by various CF members with no reduction in the incidence of pedal woes.

Ranger

Z06ufgrad2002

Ranger,
I'm definately in your camp on this issue and I also have supported and recc. to others changing the fluid before doing anything farther on clutch issues. But, I do not think this is a cure. As I religiously change my clutch fluid every month and if I drive the car hard the clutch will act up some. It helps for sure but, it's not a CURE. All it takes is a couple hard runs through the gears and the fluid is black once again and the clutch starts getting spongy.

Ranger

Thanks, Z06ufgrad2002.

The fundamental causes of the issue are heat degradation and water absorption. Those forces are inevitable; and degradation cannot be cured so long as the clutch actuator remains inside the caldron know as the bell housing. Water absorption is literally inevitable.

The cure I advocate and is widely followed, I have now learned, by pro race teams, keeps the fluid fresher than the downward progression of provoked by heat/water.

My sense is that your clutch fluid is getting too far down that the degradation slope. That's indicated by it turning black, which doesn't happen in a few runs through the gears.

Just a thought.

Ranger

Robert56@RNS

My opinion is the degradation of the fluid is only a contributor to the real problem, a weak pressure plate. Once the fluid gets comprimised, the plate issue rears it's ugly head.

Here's my story, clutch sticking to floor at about 10k mileage, while drag racing. Also, I found out real quick that it will not hold additional hp/tq. So, I decided to upgrade. Choose the Textralia when they first cam out. Guess what, Textralia supplied a new ls6 flywheel, a ls6 slave and stated to stick with the stock master. Well, after over 200 sprayed passes, and rw torque reaching a high of 665 lbs ft, and rwhp at 575, the clutch has never stuck to the floor again (except one time when I did 8 back to back hot passes on the spray). So, my contention is, it's not the hydraulics as the primary issue but rather the pressure plate.

Now am I saying that Ranger's trick does not work, not not at all. But, think it's more of a bandaid fix covering the real culprit. I follow Ranger's rec, somewhat, I may change out fluid every 20 or so passes, or when I feel like it. In conclusion, if you guys really want to be rid of the sticking pedal, or at least for those that Ranger's idea dosen't work, then get a new aftermarket clutch disc/pressure plate.
Robert

Ranger

^^^ Hi Robert.

Aftermarket performance clutch features much higher clamping power. That means they will produce less slip (we all know that). The reduced slip means less heat generated. That in turn is less likely to boil the fluid in the clutch actuator (slave).

There are four threads going on the subject, all with some good info and perspective.

Ranger

80shilling

I had the problem with the clutch sticking/on the floor. I read the advice from Ranger about changing out the fluid, so I had my mechanic change my fluid out.. He complained when I asked him to do it, telling me that I had to drop the transmission or something, so I told him to use the Turkey baster method and repeat as many times as necessary. I also had him put in the Motul 600 fluid. Problem solved, I did a two day weekend at Sears Point/Infineon raceway, here in the Bay Area and didn't have an issue the whole weekend. It had been that if I was driving on the street and gave it three or 4 hard pulls in a row, the clutch would go soft and then stick to the floor. When my mechanic changed the fluid out, it was black and almost sticky like Treacle...

I am going to have the remote clutch bleeder installed to make this easier to do regularly and to allow for a COMPLETE flush... My mechanic is also going to re-route the lines so they are further away from the heat sources in the engine bay, also he is going to wrap them and put some heat shield between the lines and the headers (about 6" gap from lines to shield..)

Hope that helps.

Robert56@RNS

Very true. So it still may be heat and thus a degradation of fluid? But, not really the hydraulics in and of themselves?
Robert

Ranger

Exactly. The fluid is so dirty and degraded from heat and moisture that it's boiling point is easily reached when heat is generated during aggessive clutch action involving launch or repetitive high-rpm shifts.

Clean fluid, at its nominal boiling points, accommodates the heat. And because of it's minimal water content, the relevant number is the dry boiling point.

The color is the tell of degradation.

Ranger

Z06ufgrad2002

If that is in fact the case. Why does the problem exist even though the fluid is reaplaced monthly, far above any standard in the automotive industry. And the issue is very reproducable with hard shifts when running through the gears.

[quote] That's indicated by it turning black, which doesn't happen in a few runs through the gears. [quote]

Actually, IT DOES. Especially with engines that have been modified. Probably due to the increased HP/Torque and increased slippage on the OE clutch.

There should not be enough moitsture accumulated in the system in a one month period of time to account for anything malfunctioning.

Ranger

^^^Black fluid is seriously degraded and offers much less than nominal protection from boiling. The clutch actuator (slave, containing crucial fluid to make it work) are inside the bell housing. That environment is at 230 degrees under normal conditions.

Launches and repetitive high-rpm shift raise that temp because the clutch mating surfaces produces friction when they slip. Friction produces heat.

These are powerful cars, with clutch fluid located in a very hot place. Not surprising that it degrades quickly. And again, that's why pro race teams bleed the clutch hydraulics daily.

Running with discolored fluid is an open invitation to pedal issues. And pedal issues lead to tranny damage. I am determined to avoid both. The path is simple.

In aggregate, annually, I spend about the same amount of time changing my oil as I do changing the clutch fluid. The clutch reservoir is much quicker and I do it more often. But I don't find either job demeaning. Just part of the deal in owning a powerful car and giving it some aggressive driving.

Ranger