Ranger

GM has published a document that specifies GM Super DOT4 fluid, or equivalent, for the clutch of all Corvettes. That's the fluid shown in the video, along with the Prestone DOT4, which is equivalent. There a lot of DOT4 fluids that can be used. Those two I've personally tested extensively with excellent results. DOT4 is the way to go.

Just keep in mind, there is no magic fluid. All will absorb water over time and become infused with clutch dust if you drive aggressively. It's the clutch dust that kills the seals in the hydraulics. Frequent swap are needed, no matter which fluid is used.

Ranger

ptindall

Indeed. But the wet boiling point of SRF is 518 degrees. The wet boiling point of Prestone is 311 degrees. So I would hope that in the case of partially comprimised fluid, the symptoms would be less likely and/or less severe with the SRF. Clearly the Prestone works great when everything is functioning properly and the fluid is clean throughout the system. But in cases like mine, I think the higher wet boiling point of the SRF is likely to help. It certianly can't hurt. It just costs more.

sothpaw2

Amen. Where do you get a good price on SRF? I just might try upgrading from Motul.

ptindall

If you find out, let me know. I buy it from DRM (Doug Rippie) for $69.95 per liter.

Ranger

There are a lot of high quality brake fluids that will do very well in the clutch hydraulics. SRF and Motul are two of them.

But keep in mind that water in the fluid from heat-cool cycles is just one issue, and it doesn't adversely affect the seals. The more serious issue is the infusion of clutch dust which does damage the seals and leads to their eventual failure.

So the key thing is not allowing the fluid to remain dirty for long. That means frequent changes in cars driven aggressively.

Ranger

PlanoLeMans

Just went out and purchased all the necessary stuff to do the Ranger method. It worked like a charm. The car had only 4k miles on it and I did 2 cycle of the clutch cleaning. I will drive it for a bit and see if the fluid changes color.

It looks good now and had some brake fluid left so I also exchange the brake fluid. Not sure if it matters but I decided that it could not hurt.

Thanks for the info Ranger. Took less than 15 min and less than 10 dollars of supplies with Prestone DOT4.

Great thread,

A

sothpaw2

Me too, best price I could find. Would like to see if it can cure my occasional issues that crop up instead of trying the Master cylinder. Master would be next, then slave & clutch next year. Fluid is always clean but gets nasty in a hurry sometime if I drive hard.

Ranger

Hey sothpaw2,

That sudden cloudiness during aggressive launch and shift is the uptake of clutch dust. That's why you've seen me swapping the clutch fluid between passes at the drag strip. That practice eliminates the chance of pedal issues for me during quarter-mile runs.

Expensive fluids may help reduce the effect of water in the fluid but they do nothing to mitigate the impact of clutch dust, which is the greater problem.

Ranger

TheRedGoat

Ranger,
I just actually bought my Z this past Monday. Its a 2004 with 47,600 miles that already had cam, headers, intake and exhaust. I check the clutch fluid and it was like a black hole. I have no idea if it was ever changed. Last night I followed your method. The bottom of the reservoir was really dirty to. I cleaned all that out good. Then I flushed it 3 times. The clutch pedal still feels a bit crappy after high rpm shifts when I tried this morning. The pedal just doesn't come off the floor like it should. You think its the master cylinder?

-Adam

andrewjhaley

Adam,,,
Don't give up on the procedure. What brand of fluid are you using? You can't fix what is assumed to be 47k miles of no clutch fluid care in one evening, do it everytime you drive the car. I am sure if you check the fluid now, its black again. So go out there and drive it!

sothpaw2

I find that I have to drive the car to really see if the fluid is going to change. If I just pump the pedal in the garage, it always comes up clear as a whistle.

Do the change every night after you drive (let it cool down) for a week or 2. Don't drive hard or get into the high rpm range.

sothpaw2

Hi Ranger,

I certainly wouldn't advocate neglecting the fluid because it's better. But whereas you're have success w/keeping the pedal working perfectly by changing after each pass, changing after each pass did not work for me last year; the pedal still had issues even w/ Modul 600 RBF. And it the fluid each time looked perfect, no color change or dust in it; felt like a waste of good fluid. The only thing that made the pedal waaaay better was to let it cool down. The car is incapable at this point of doing even 3-4 consecutive passes; the fluid needs to cool between.

Once I do a clutch, slave, & master, I'll be doing a lot more passes, believe me. Right now I only do 5 per year.

TheRedGoat

I used the Prestone Syn DOT 4. I will check it again when I get home. Man... I'm gonna have to buy out all the bottles of the Prestone stuff at Walmart....lol. I also have to get the brake fluid flushed too. That stuff is blacker then black. Thanks guys.

sothpaw2

Good go buy up the Prestone. If that doesn't clear up your issue, you can try something more expensive. Prestone is a decent bang for the buck.

Iowa_Z06

Is the C5 Z06 not made to be more of a road track car, vs. a drag strip car? Drag racing is brutal on many parts. When road tracking, your throttle modulation is more gentle (i.e. you are not "romping" on the throttle).

crAzy

I need to do this when i get home today. Also is the procedure the same on the brake master cylinder? As in suck out all the dirty fluid and replace with new fluid, pump the brakes, and drive around for a bit. Then repeat if needed?

froggy47

No, use a standard brake bleed procedure, add a tech II bleed if you want to include the abs (I usually don't include the tech II, but I bleed about 4x a year or more, & activate abs - with my foot - often)

crAzy

Yea i was going to use my brake pump for cleaning the master cylinder for the clutch. So bleeding the brakes I would jack the car up on all 4's, start with the furthest wheel from abs and work towards. Use the brake pump to suck out the fluid and keep an eye on the resivoir so that it wont suck in air, correct? But im assuming i would remove the fluid from the resivoir 1st. Then clean it and add new fluid and then do the bleeding procedure right>?

froggy47

Yep.

crAzy

Thanks...