Vinsanity

I checked the fluid and it was pretty black and murky. So I ran process from this thread until finally it was nice and clean. Drove it gently for a day or two, and it's dark gray again. I've now down this twice with the same results. Should I be concerned? I bought a used '07 with 7500 miles, so I don't know too much about it's history other than it's stock still.

I'm using Valvoline Synthetic DOT 3/4 because surprisingly I can only find Prestone DOT 3 not DOT4 around here. I can look harder if the problem is Valvoline sucks.

Ranger

I avoid Valvoline products for any Corvette clutch. They seem to react badly to the seals in the hydraulics. I used it once as a test. Never again.

Suggest you hunt down another good DOT4, such as the two shown in my video.

Ranger

ls3rylec6

looks like im having this done as well when my car goes in the shop haha.

Ranger

If the shop does a conventional bleed of the clutch, it will cost you about $125 and that method will not get rid of crud that's caked in the hydraulics. The inlet and outlet are right next to one another, creating a very shallow flow that leaves behind accumulated clutch dust that will go back into suspension and re-attack the seals.

This is a case where a self-help procedure is not only cheaper but also much more effective that what the dealer does.

Ranger

Vinsanity

Thanks, I'll hunt some down and do a reflush and see if it persists.

TLK

I've flushed twice now in the last few weeks. Still returns to murky, but takes less to get clear again.

The car sat for a week while I was away, and I notice a single drop of something that looks like dirty clutch fluid on the floor of the garage approx where the transmission sits when I got back. Could the flushing procedure of repeated rapid clutch movement cause some fluid to escape?

Ranger

Hey TLK,

The clutch pedal pumps articulate the clutch hydraulics (master cylinder and actuator) which are behind the engine but forward of the torque tube. A drop on the floor near the tranny would be unrelated to clutch pedal movements.

If the drop is definitely oil-like then it's tranny or diff overflow/weeping.

But if it's water-like but dirty, then it may be condensation from the exhaust system that drips from the aft connection clamp and brings along soot as it drops off the pipe.

Ranger

rjacobs

Did this on Sunday and noticed an immediate improvement in clutch pedal movement and feel. I just used some cheap DOT 3 fluid my buddy had in his garage. I am going to do it again once I get some Motul RBF600 fluid. Also looked at my brake fluid, the car had a brake job at 15k when I bought it, has 20k now, and apparently they did not bleed the brakes since the fluid is black and nasty.

ls3rylec6

im having Tom over at "wong's performance" do it for me, i think he will know this method sense he is a forum member. (TJwong)

FastEddie09C6

as far as the replacement fluid i know DOT4 but should it be synthetic? (if it is even made?) i have almost 900 miles on my 09 coupe and its a little murky....

regorih

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tkbrooks22

Ranger, I followed your instructions and did the flush....a whole pint of fluid, 30-50 pumps of the pedal, cleaned and refilled 15 times and the fluid is still light gray...not DARK..DARK gray. Will it ever be clear? How can I tell if my o-rings are bad or I have damaged seals? How do I do a visual inspection? The petal feel is a lot better. By the way...this is a car that is a road racer..full cage & 488hp @ the wheels. Thanks Tom

05C6400

Just curious if this applies to normal driving conditions... that is no fast starts or hard accelerations.

Ranger

If the label says "DOT4 brake fluid," it should be fine for your clutch. I favor the two fluids shown in my video, but Post#1 in this thread contains a link to a list of DOT4 brake fluids that are suitable.

The term "synthetic" when applied to brake fluid is just marketing. All brake fluid is synthetic.

Ranger

Ranger

Suggest when doing the pedal pumps to make certain you go from full clutch-out to full clutch-in to full clutch-out, and perhaps slow down the motion a bit.

If you continue to do the fluid swaps before and after days at the track, you will negate the accumulation of clutch dust and water that are otherwise inevitable during sessions.

You will know if clutch hydraulic seals become compromised by the pedal woes that start adversely impacting shifting at high rpm either up or down.

Ranger

djbrun

I just checked mine, with 2K on the clock, very mild driving. I shift before the cags will kick in. (Black!!) I was pretty surprised.

05C6400

I guess I better check mine out as well...

Jimmyz28

There has to a cure for this. What about replacing the slave and master cylinder with larger (read drill-out mod) truck slave and master? Why isn't GM fixing this under warranty? I spoke with a local tech (and he's a corvette tech specifically) and he's not seen anything from GM on this for a fix. All the after market tuners want to do is replace the clutch assembly. That will NOT cure this problem will it?

Mine's doing this badly now (fluid's pretty clear 4700 miles on the clock) and I've flushed it 5-6 times now.

Ranger

If it started out black and unchanged since delivery, you've still got penance to pay. Keep swapping until it stays clear after a good drive.

Then, if the pedal still acts poorly, you have a warranty claim if they overlook the mods. The only thing you'd want to do is a R&R of the master cylinder. Clutch dust, if allowed to accumulate destroys integrity of the seals. That has little to do with the orifice size (ala drill mod). Clutch dust involves shard of copper and iron.

Think of it like sawdust in your eye. The eyelid causes lacerations. Same with clutch dust if you don't deal with it. Watch the video. The story is there.

Ranger

Jimmyz28

It was never black. A little murky but that's it. I'm also using Valvoline and after doing some more reading it seems that that fluid is NOT the one to use. So you're saying the clutch master cylinder could be the culprit if the flushing doesn't work?

Thanks,
Jim