thebishman

It's nothing like that; there is no dripping of fluid whilst stationary or applying the brakes even on the street. It's just on the track at an HPDE, the outer brake bleed adapters are 'seeping' fluid at all four calipers. This 'seepage' is enough to coat the outer portion of the calipers, and to coat the wheels with a sheen of brake fluid. On a couple of occasions I've had traces of brake fluid running along the bodywork behind the wheel arches in the front. At my last event I had to check the brake master cylinder after every run session, and top up as necessary.

What's frustrating is that while I am in no way considered a slow HPDE driver, I'm more of a momentum driver, not a point and shoot type; hence I'm not even really hard on my brakes!

Bish

AzDave47

Bish,

Have you tried tightening the outer bleed screws with the brake calipers hot? You should be able to do that with wheels on thru the spokes right after the car comes in from hot lapping. There could be differential expansion between the aluminum calipers and the steel bleed screws.

Differential expansion was why the C6 Z06 pad retaining bolts would loosen and back out with track use even if torqued to spec cold.

thebishman

That's a damn good idea, but I haven't done that. In fact, one of the reasons GM Exec gave me was that the leaks were being caused by me tightening everything down when the brakes were hot. When I told them I've never done that, they stopped using that reason as an excuse. Also, I would be afraid of shearing off the top of the brake bleeder by over tightening, which is a real cluster when that happens.

I absolutely agree that the reason the bleed adapters are leaking/seeping fluid when really hot on the CCM brakes is what you stated: there is a different expansion/contraction coefficient between the differing metals used, and the fluid is seeping around the threads somehow.

Why GM isn't taking this seriously is beyond me as it really could be a safety issue on a road course if someone gets air in the system because of this. The bloody brake fluid could also destroy the finish on the bodywork, caliper, wheel, etc. Luckily I have the whole front end covered in Xpel Ultimate so that is helping in that regard.

Interestingly enough I was told by GM Exec two days ago that they, the Corvette 'team' had "never heard of a Corvette doing this before". My response to that was, then if my car is an outlier, wouldn't that be a great reason to exchange parts and see if the calipers on my car were in fact manufactured incorrectly? Apparently using logic doesn't work! lol

Lastly, total cost of the calipers at all four wheels is about $5K MSRP; GM's cost would be of course much lower. It would take my tech at the dealership who is a highly skilled Corvette specialist, what, two hours to replace everything and send the old parts back to GM? I can't imagine that a total cost to GM of <$4,000 is going to put them back into bankruptcy.

IF this was Porsche I can guarantee that those calipers would have been off the car immediately, although on second thought, they actually wouldn't have leaked in the first place!! lol

Bish

dvandentop

wow what a horrible outift surprised by lack or care by anyone in management.

spearfish25

I'd buy some AP Racing brakes and be done but I have steel brakes now.

thebishman

I have dealt with Jeff at Essex before with my '09 GT-R, and he is a true enthusiast and stand up guy. I can't recommend him and Essex enough.

I may in fact do that very thing if I decide to keep the car; I just wish AP racing had a kit to replace the rear CCMs also.

Bish

spearfish25

The OEM steel rear brake kit is probably not very expensive.

thebishman

I really wish that AP Racing made replacement calipers for the CCM rotors front and rear. I love the rotors, and I'm **** about checking pad depth to make sure I don't screw them up.

Batman 357

Did the fluid damage your rotors.

thebishman

No as the fluid seemed to exit away from the caliper luckily

dvandentop

They will have one by spring I am guessing Jeff said he has several people running iron up front and CCM in rear

jagamajajaran

Here's some additional feedback that I received today...

schaibaa

Have you considered buying just one rear caliper to see if that fixes it? Even if there was a bad casting, it seems odd that you would get bad fronts and rears.

I I know you've changed the bleeders too but maybe the run of bleeders was bad and the threads caused the taps in the calipers to be damaged.

Based upon everything ive read it certainly has to do with differential expansion rates - so something must be off with the threads in some way.

Best of luck!!

thebishman

Appreciate the follow-up. As I've mentioned I've only ever torqued the bleeders when the brakes were at ambient temps, and the amount of fluid lost is orders of magnitude greater than that which remains within the barrel of the bleeder after a flush/bleed.

Bish

X25

Are you sure you lost the fluid from bleeders? The only time I saw a car losing too much fluid was from the pistons, not from the bleeders.

thebishman

I am almost 100% convinced that it is an issue of the bleeders. BUT, my dealership wouldn't even touch the brakes to check Pistons, etc. since GM refused to pay for any warranty work on the brakes.

AzDave47

My C6 Z06 lost fluid from the bleeders at track events when they got very hot. I had to tighten them so much, but not as tight as GM does the flair nuts on the hard brake lines. Those get factory tightened enough to distort the flair nut threads and make changing to SS braided lines more difficult.

thebishman

Good to know. Thanks.
Bish

descartesfool

From the Brembo 2016 catalog:

"The M 10x1 bleed screws tightening must be carried out with a
torque of 12 - 16 Nm."

That is 8 to 12 ft-lbs, which is more than you might think when tightening with a small hand wrench. I often check with a torque wrench when doing a bleed at home, but you need one that is made to read small torque values.

As for Speed Bleeders, I have been using Russell ones for almost 20 years on about 5 different track cars, and I have only ever had one leak at the threads when it was loosened to bleed the brakes, and I called them and they sent me a free replacement. Other than that, they are fantastic in my long experience of bleeding brakes on multiple different calipers, including Brembos. I have never had one leak after it was tightened. They certainly make brake bleeding really easy, and all you need is one or two brake bleeder bottles, like the ones made by Genesis.

spearfish25

Does two pints get you through a full flush?