leadville1

I went to a two day event at Road America this weekend with the Northwoods Shelby group and ran my car in advanced. A little background I have over 14 years of driving on the track and am an instructor in the BMW club.

After reading the track threads I did several pre-cautionary actions to hopefully have a reliable track car. These were the things I did prior to running the car.

1. Radiator - I added Red Line Water Wetter
2. Replaced all the stock fluids with Red Line Dif/Tran, Oil 15w50 Mobil 1
3. Track Alignment - They didn't get the caster set but toe and camber
4. Replaced stock lines with Stainless Steel Spiegler lines/683 degree fluid
5. New rotors for the track/Carbotech XP20 all around Cooling rings
6. Bought Cray wheels and installed Pirelli scrubs 18/19 wheels

So I am thinking I have done everything I can, I need to watch the brakes and learn the car before going full out. First session out the Vette is easily the fastest car, the grip and turn is amazing. I am driving it in Sport with the traction control on the first time out. The torque coming out of the corners is simply amazing and the car handles extremely well, If I trusted the brakes I would be flying in this car.

I watch the temps with an ambient outside of 85 degrees the water temps stay steady at 220, never saw a rise the whole time on the track. Temps in the trans also never go above 200 with the wrap. After about three laps when I got into a braking zone I hear a sizzling sound again and again. I think it may be related to the cooling rings (safety wire did exactly have me certain on these). Then I notice the pedal getting soft and going deeper, I either have boiled the fluid or have air in my lines. The session ends I bring it in and look at my calipers...Ahh I have brake fluid coming out of all 4 bleeders and the nice new red paint is flaking off as I wipe it off.

I went and talked to a few people on what could be wrong, torque on the bleeders, fluid out gassing? Nobody has ever seen or heard of this happening before. The best I can do is re-bleed the system with new fluid and torque the bleeders. I do this and go out for a second session, but not before I decided I was confident enough in the car to put on my track rubber. I bought a staggered Cray set up with 18/19's since the configurator and seller told me no problem these fit your car. Guess what they DON'T. The fronts didn't clear the caliper, at this point I am about ready to put the car up for sale. Back on with the stock wheels and out to the track. First three laps are good excellent brakes going deeper in the corners and trusting them, then the sizzle comes back. I don't go any further I pull in the paddock and sure as heck more fluid coming out of the calipers.

I packed the car up and took it home before something catastrophic happened on the track. Here is what I will say about the car positive though.

1. Temps stayed in check with the changes I made.
2. 2 sessions didn't show any serious brake wear on the pads or rotors pretty solid transfer of material, I still will never fully trust these brakes.
3. Stock seats were excellent even with a three point belt I felt secure and didn't move around much.
4. Incredible grip and ability to pull out of the corners, would have liked to disable the TC to really learn the car.
5. Tires looked like they were wearing perfect after two sessions and the stock tires have great grip for a street tire. Most Novices or even intermediate drivers would struggle to need more tire if they weren't doing a lot of track days per year.

I went back home put the Vette in the garage and pulled out the old M3 went back to the track and had a blast, I never once worried about my brakes with a 4 wheel Stoptech kit. I want that feeling in the Vette but I am not willing to shell out another 5k just to stop.

I am pretty confident if I go back to the track with this car the fluid issue will show it's face again, until that is resolved it is a street car which is only part of what I bought this car for.

robertf97

Maybe try some new bleeder screws. They may have been over torqued at some point and the sealing surface ruined.

Greg00Coupe

Pretty crazy. I had the same experience with my brakes on one corner.......BUT it was due to me not snugging down the bleeder enough. What surprised me was how much fade there was with just one "loose" bleeder at speed. You did the right thing to take it home until you figure it out.

I hear you on the brakes. After reading some posts here I am a little gun shy with the car too. Hope to gain some confidence with more track time in the car.

travisnd

Did I read this right that the front wheels rubbed the calipers? Did they hit/damage the bleeder screws?

leadville1

I tried to fit them and they don't clear the calipers, it didn't touch the bleeders this all happened after the failure.

FormulaRedline

This is unfortunate to hear. I had no problems (boiling or even fade) in any of the cars at the Ron Fellows level 2 school on stock pads and rotors (with cool rings installed, some sort of DOT 4 fluid obviously). However, while that track was out in the desert and we probably had similar ambient temps at the time, the track configuration was much slower than Road America. More frequent braking...but from much lower top speeds.

Maybe the combination of the speeds and the more aggressive bite of the Carbotechs pushed it past the limit? But that would suggest the fluid boiling was the problem...does that match with the type of fade you were experiencing (gas in the lines)? Or more like the pads/rotors were overheating/glazing?

Also, what driving and PTM modes were you in? It's important to note that most of the stability control in this car applies the brakes. If you are an experienced driver at a track you are familiar with, it's very likely the car was going nuts applying the brakes at all 4 corners to try and control the rotation (it doesn't know that you know what you are doing lol) all the way from turn in until track out. For a novice driver this might be ok because they wouldn't be using the brakes fully anyway, but for an experienced driver hitting high top speeds and trail braking deep into the corner, this is probably too much work for the stock system one way or another.

Maybe try another weekend with the aids turned all the way off? Just be careful getting on the throttle!

leadville1

If the bleeders were letting fluid out they were letting air in. That was definitely the issue. The fluid was way too high of boiling temp to be the problem, and when have you ever seen fluid not boil out the resovoir vs. the bleeders. I have never seen a bleeder leak. this was all the bleeders.

I think it has to be an issue with the brakes themselves, perhaps the aluminum bleeders vs steel. Or they were machined incorrectly, the issue wouldn't show up on the street unless you were threshold braking.

FormulaRedline

I read your other thread, too, and think I agree with your assessment. Whatever the temp of the fluid and regardless of any problems that may be leading it to heat up, it shouldn't be coming out of the bleeders first.

W88fixer

I do NOT pretend to be an expert here and absolutely no intention to criticize anyone.

I’ve talked to GM dealer service managers who say if the brakes aren’t bled with something like the GM dealer's equipment, there’s always the possibility of problems. Could this be a factor? Don

leadville1

What special GM equipment do they use on Brembo brakes?

This is the shop that bled the brakes, I guarantee you they bleed more Brembo's than a GM shop does.

http://www.kellymossmotorsports.com/

Bleeding brakes is pretty straightforward

descartesfool

I bled my brakes myself on my Z51 to replace the fluid with Castrol SRF before my first track event with the car and I had no issues at all with brakes. I simply bled from furthest caliper to closest, with no special equipment except a bleeder bottle and a wrench, plus a bleeder club member wife! Did torque the bleeders to spec with a torque wrench too.

I have never heard of fluid leaking out the bleeders, and I have been bleeding my brakes for the track for 18 years now. Very curious.

*C7*

Bleeders seeping is nothing really new. It was not uncommon to see C6 Z06 calipers seep at the track.

I had 1 of mine on my Z51 C7 seep a little at Sebring.

leadville1

Are you really saying this is normal for Brembo calipers?

I am sorry I don't buy it. I have pounded on Stoptech's at the track and the only fluid that ever overflowed was in the reservoir.

*C7*

No, I'm not saying that at all. I don't believe the C6 Z06 calipers were Brembos anyway.

I was really surprised to see the same issue with the Brembos on the C7.

I think it just comes down to the fact the calipers are getting too hot and the seal at the bleeder is being compromised.

3 Z06ZR1

thanks!
Nice review! The stock tires are great in my book too!

turbo8765

My track car weights 2700 pounds and has stoptechs, ducting, r-comps, SRF, and titanium backing plates.

By the end of the day at VIR I was using the same braking points in my C7 (stock except XP20/SRF) as my track car with no fade.

Sounds like your bleeders may have been improperly torqued.

I've had similar seepage from a stoptech caliper and a brembo. I asked Autometrics about it and they suggested it was residual fluid in the base of the bleeder. I didn't believe them initially, but it did only happen on the first track event are fluid replacement… and not subsequent track events.

There are no special tools required to bleed the brakes, sounds like another excuse to charge your for something you can easily do yourself. Just follow the order noted by descartes… RR, LR, RF, LF.

leadville1

It definitely wasn't excess fluid, everytime I would hit the brakes I could hear it sizzle and not just a little it was a lot, then when we bled them again we again torqued the bleeders to factory specs and got the exact same results. Two laps and then sizzle on every corner under braking, followed by extreme pedal fade because there was air in the system.

I literally have done probably close to 100 events in my Stoptech's and never saw this happen.

Jay Farber

I love how OP is getting logical first hand responses from people who have experienced the same problem and his response is just "Nah, can't be me, gotta be something wrong with the car"

You've done close to 100 events? So what if there is about a 1% chance of the bleeder screws being over torqued or there being some residual fluid left? You're right on that threshold aren't you?

leadville1

When I got done with a session I pulled into the paddock parked the car, looked at the caliper and the fluid was bubbling out of the bleeder at the threads, how much more definitive can that be that it wasn't excess fluid.

If you also read my original thread you will see I wasn't pushing the car or doing excessive threshold braking since it was my first time out in the car and I was learning the car, this would be what I would expect from an Intermediate driver, earlier braking more coasting into the apex rather than trail braking.

I pounded my Stoptech brakes right after the Vette was finished for the day in my M3, I know the difference.

I also know when something isn't right in a car and this isn't right. If it is I am ripping these brakes off and using them as paperweights. Brembo wouldn't manufacture a performance brake designed to vent through the bleeders. Also when your using a torque wrench to set the bleeder torque how much more accurate can you be.

travisnd

Something is amiss... fluid squirting out of a torqued bleeder means the seat in the caliper has deformed and is no longer sealing. This would be VERY hard to do. Or you somehow got bad a calipers or the shop put the wrong bleeders in.

A tiny bit of fluid is completely normal if you don't clean up the excess that will weep out before hitting the track.

1. Fluid gets into the bleeder screw threads when bleeding and will seep out once the bleeder is torqued. This is more prominent if you use a Motiv power bleeder vs. old fashioned pumping.

2. Fluid will be in the center of the bleeder screw and will ooze out as well.

Personally, I take a paper towel and twist the corners and stick it down the bleeder screw hole to get the left over fluid. Also, I usually have my car on jack stands and 30 minutes or so after bleeding I go and wipe up any excess dribbling around the bleeder screw threads.

To be clear, if any more comes out after you've cleaned the excess or when you pump the pedal you have a problem.