Flushing the brake fluid issues. Brake failure.

[GONMAD510]

Does the brake pedal come back if you pump the brakes? The pads could be getting pushed back away from the rotors.

[Russell James]

Take an infrared temp gun to the track next time and check rotor temps coming off track. In mode 3, active handlings is still working. Whenever AH is doing it's job... rotor temps can skyrocket fast.

I learned that on my 1LE. Whenever I did a track session with active handling still on, rear brake temps were screaming hot and way over front rotor temps.

Not telling you to go past level 3.... turning off all the nannies before you are at pro level is a good way to wreck the car. But just saying....when AH is still on... the brakes can get screaming hot very quick.

For your current situation.. you've overcooked the brakes several times. I'd consider everything done. The fluid is not the only thing damaged by a brake overheat. And it's not like all can just cool off and be back to normal. Once overcooked... the fluid is done. Any rubber part that melted is done... On a brake overheat to failure, just my opinion, but time for a complete tear down and start from fresh.

New seals and dust boots in all four calipers. Change rubber lines to racing brake lines. Add cooling ducts and hoses to front rotors. Check pads and rotors for heat damage.... Basically starting over. Not being able to bleed out one corner that one time to me may be a clue that caliper or line had an issue. And after several overtemps to failure, to me, time to just redo all. Tracking a car is not cheap or easy, tons of brake maintenance.

But...up your brake cooling... change your driving... monitor your rotor temps... and you can get to minimizing brake maintenance. As mentioned earlier SRF is the best fluid you can get. The trade off though is you need to change it every couple years. It has no ability to absorb moisture... so it's more of a racing fluid. It can't just be left in there for 10 years. It's meant more for racing and regular brake maintenance.

That's my thoughts. Start over with a complete rebuild of the system, fresh caliper seals, lines, pads, fluid... add cooling... watch temps... modify driving. And keep in mind that it is not a full race brake system.

To get a full race brake system that will last all day at a track session after session... get ready to spend $15K plus. Your car has a street performance system that certainly has it's limits.

Do some hots laps, then some cool down laps... then pit check temps. If you ever take it to failure on track and take it straight to the pits with everything smoking red hot... all is cooked.

[Thor142]

Originally Posted by himmy33

Sorry I haven't posted in a while. Not much new to report.

The system was bleed with a GM Tech tool so there should only be Motul 600 in there.

As far as running the car to hard I honestly feel I was not very hard on it in the last video. I use PTM 3 and it hardly steps in. I just don't push her that hard. There are a few times when the ABS will kick in very quickly but that may only happen twice a lap.

I'm not entirely sure what is happening so I will describe it the best I can:

After a few laps of warming the tires up I will start to run the car harder and that is when I start using the brakes hard. They worked for a couple laps but they started to fade. At this point I was a bit reluctant so I slowed down a bit especially on the straight. They seemed to come back a bit but still not 100%.

At this point I want to start setting some good laps so I get back in it. After one or two laps there is some pretty good fade going on so I decide to pull off the track. The pedal is extremely spongy now so I take the car for a bit of a cool down lap around the paddock. In the video at 15:14 I am pressing the brake pedal all the way to the floor and it brakes the car like a stiff breeze is blowing at me. The brake pedal feels as though I am pushing the fluid through a small opening.

I'm no mechanic or expert racing guru but I just don't feel I am over using the brakes. I have been proven wrong in the past though. To give an example there is a guy out there in a red 2013 GT500 that pushes his car far harder than mine. He gave me a ride and some pointers (It was a blast!) and he uses the shit out of his brakes and he does not suffer any problems. Other people at the track feel the same too.

Hopefully the car will go into the shop this week and we come up with a solution to the problem.

OK I don't have a ZL1 but I can help some with track brake issues. Maybe some of this applies to you maybe not.
1) Run dedicated track pads for your track days. They'll give you better bite and help you brake right at the limits of your tires so that you're not on the pedal so long.
2) Run FRESH DOT4 fluid for each track event.
3) The issue may not be the brakes as much as your driving. Please don't take this wrong I'm not pro driver and I'm just guessing here. You could be overheating from the nannies working overtime. If you aren't being smooth through your corners the traction and stability controls could be doing a lot of correction for you. This will really heat up your brakes. Work on your braking zones. If you are light braking early then adjusting pedal pressure and trail braking all the way into the apex your generating a ton of heat, then if you're not smooth coming out of the corner with the throttle the brakes are still working to keep you straight. Get most of your braking done in a straight line. Get it done quickly. If you need a little trail brake after to set the balance on the front corner of the car it's ok but make sure you aren't riding the brake into the apex. Track out as wide as you can.Get the car straight before applying too much throttle. I've had the nannies correcting me plenty of times on track out because of too much throttle too early and I have way less HP than you do. It makes heat.
Hope this helps. Again, I'm not at all trying to be a know it all. I've never had any brake fade even after a 30-35 min session and I'm running stock except for pads and DOT4 Motul 600 fluid.

[Aliveguy5]

Originally Posted by himmy33

What do you mean by the brake pads themselves? There was one guy on the track that mentioned he has had his brake pads over heat before. Totally different car than mine but I thought it was worth a shot. I haven't heard of brake pads overheating. Can anyone shed some light on this?

Brake pads can get too hot and become very "greasy" and you will lose braking power due to the metal losing it's composition. I also think two things are going on here as I diagnose this over the internet. I think either you are getting your brake lines really warm and the pedal is getting spongy and you are losing your confidence in the brakes or, your nannies are stepping in much more than you think they are and heating up your brakes way too much. The car is completely different from PTM3 to PTM5 or off. As I said I run Motul 600 and I get a spongy brake but never a complete failure. I think your PTM may be stepping in a lot. You have a lot of good suggestions here and I think you should take an infrared gun with you. I also would check to see if you have a caliper sticking.

[Thor142]

Originally Posted by Aliveguy5

Brake pads can get too hot and become very "greasy" and you will lose braking power due to the metal losing it's composition. I also think two things are going on here as I diagnose this over the internet. I think either you are getting your brake lines really warm and the pedal is getting spongy and you are losing your confidence in the brakes or, your nannies are stepping in much more than you think they are and heating up your brakes way too much. The car is completely different from PTM3 to PTM5 or off. As I said I run Motul 600 and I get a spongy brake but never a complete failure. I think your PTM may be stepping in a lot. You have a lot of good suggestions here and I think you should take an infrared gun with you. I also would check to see if you have a caliper sticking.

Not trying to argue here but I've never heard of brake pads getting "greasy" unless they weren't bedded and you get a layer of hot gasses between the pad and the rotor. How do pads get greasy? I'm willing to learn.

[Russell James]

Originally Posted by Aliveguy5

Brake pads can get too hot and become very "greasy" and you will lose braking power due to the metal losing it's composition. I also think two things are going on here as I diagnose this over the internet. I think either you are getting your brake lines really warm and the pedal is getting spongy and you are losing your confidence in the brakes or, your nannies are stepping in much more than you think they are and heating up your brakes way too much. The car is completely different from PTM3 to PTM5 or off. As I said I run Motul 600 and I get a spongy brake but never a complete failure. I think your PTM may be stepping in a lot. You have a lot of good suggestions here and I think you should take an infrared gun with you. I also would check to see if you have a caliper sticking.

That's what I was talking about too with the PTM mode 3 the OP is using.

When I track a car, I tend to trail brake... throw the car into the apex hard braking a bit slideways... and rotate the ass end around... then hammer down on corner exit letting it run out to the exit cone. This drives the nannies crazy sliding the car around like that. If I drive my 1LE on a track like that with AH still active ... the rear brakes are screaming hot after a 20 min session. With AH turned off driving like that.... when coming off track, rears are cooler than the fronts.

If the nannies are on and trying to fight your cornering or driving style... those rear brakes will get screaming hot fast.

Next time at the track, take a temp gun and watch the brake temps using various modes and driving styles. If AH is working overtime, you'll be amazed how hot your rear brakes are. You're trying to slide a car around a track, and the computer is trying to keep it straight using the brakes. You might think you're being relatively easy on the brakes... but the AH computer is hammering them in the corners.

But...don't turn the nannies off on a ZL1. Until you are at that pro level of driving. Very easy car to wreck with the AH off. Just know that with it on... it can cook your brakes.

[ZMEnow]

Originally Posted by ZMEnow

So in an earlier post you stated the GM tech couldn't get the RR to bleed fluid, but in a later post you noted the tech worked with a GM specialist to complete the bleed and clutch. Just curious what did he do to get the RR to pull fluid, change the bleeder valve?

Also watching your video is that after the GM bleed? just asking because if you ran that hard that long I don't think there is a air in the system. Also if the end of that video is a brake failure I will send you a video of when I boiled my DOT 3 fluid and the only thing between me and the wall all the way back to the paddock is the hand brake.

Even after 20 mins I still hand nothing. It took about an hour to get enough pressure to safely drive home and from your video things look pretty good the last couple of turns. Did you provide them the DOT 4 fluid to put in?

So you never answered the question on how the mechanic fixed the RR not pulling fluid through the bleeder valve. Also have you noticed any fluid around the MC cap at the end of your runs? This is starting to maybe sound like a vacuum leak.

I wouldn't say its the booster because they will start out with hard peddle pressure but as the air progresses in the line the spongy-ness appears. The booster will some times throw codes, so not sure that's it but you have tried everything else so I would starting looking at vacuum leaks.

[Russell James]

Well, his brakes failed from a severe overheat. And then couldn't bleed a rear?

My guess would be the rubber parts melted in that caliper. Crud/melted crap... could have been blocking the bleeder. One could have a helper pump up the brakes, and pull the bleeder all the way out see what comes out.

Which is why, after an overheat to failure... I consider the brake system done. Rebuild all four calipers with new seals, new fluid, check pads and rotors for damage. I've never seen a sever brake overheat that didn't kill the caliper rubber parts or fluid.

Some think they can just let it cool down and go at it again. Nope. It's like burning the cookies in the oven. Throw out that batch, start over.

[frankwjr]

Originally Posted by Russell James

Well, his brakes failed from a severe overheat. And then couldn't bleed a rear?

My guess would be the rubber parts melted in that caliper. Crud/melted crap... could have been blocking the bleeder. One could have a helper pump up the brakes, and pull the bleeder all the way out see what comes out.

Which is why, after an overheat to failure... I consider the brake system done. Rebuild all four calipers with new seals, new fluid, check pads and rotors for damage. I've never seen a sever brake overheat that didn't kill the caliper rubber parts or fluid.

Some think they can just let it cool down and go at it again. Nope. It's like burning the cookies in the oven. Throw out that batch, start over.

Yup...

[ZMEnow]

Originally Posted by Russell James

Well, his brakes failed from a severe overheat. And then couldn't bleed a rear?

My guess would be the rubber parts melted in that caliper. Crud/melted crap... could have been blocking the bleeder. One could have a helper pump up the brakes, and pull the bleeder all the way out see what comes out.

Which is why, after an overheat to failure... I consider the brake system done. Rebuild all four calipers with new seals, new fluid, check pads and rotors for damage. I've never seen a sever brake overheat that didn't kill the caliper rubber parts or fluid.

Some think they can just let it cool down and go at it again. Nope. It's like burning the cookies in the oven. Throw out that batch, start over.

We don't know what the out come of the RR bleed was at the Dealership with the GM Tech support assist because he has never answered how they got it to bleed other than they did. I personally ran my Dot 3 fluid 5 20 min track session before I boiled with complete loss of brakes, hand break only.. i blead the next day with Dot 4 and they continue to work great. I have watched several other Zl1's and 1Le's do the same with no problem.

I had the pleasure this summer of spending sometime on Woodward talking with one of the Brembo designers on the ZL1 system regarding Brembo Pads vs. Hawks. He was telling me they were out West testing Hawk Pads on that system and were literally melting the pads on the cars, and there was no damage to the caliper. So while its certainly possible to damage a boot seal, it would be my last plan of action on this particular setup.

[cdb95z28]

Originally Posted by ZMEnow

So you never answered the question on how the mechanic fixed the RR not pulling fluid through the bleeder valve. Also have you noticed any fluid around the MC cap at the end of your runs? This is starting to maybe sound like a vacuum leak.

I wouldn't say its the booster because they will start out with hard peddle pressure but as the air progresses in the line the spongy-ness appears. The booster will some times throw codes, so not sure that's it but you have tried everything else so I would starting looking at vacuum leaks.

Fluid at the reservoir and cap is from fluid leaking out of the vented cap/diaphram due to a pressure increase (from an increase in fluid temperature). Keep the fluid level a tiny bit lower than the "max" line or just accept that the wetness is normal

[JusticePete]

Originally Posted by Thor142

Not trying to argue here but I've never heard of brake pads getting "greasy" unless they weren't bedded and you get a layer of hot gasses between the pad and the rotor. How do pads get greasy? I'm willing to learn.

Brake pads are like tire tread compounds. They get ssoft when they get hot. Get them too hot and they get greasey jusst like an overheated tire.

Originally Posted by Russell James

Well, his brakes failed from a severe overheat. And then couldn't bleed a rear?

My guess would be the rubber parts melted in that caliper. Crud/melted crap... could have been blocking the bleeder. One could have a helper pump up the brakes, and pull the bleeder all the way out see what comes out.

Which is why, after an overheat to failure... I consider the brake system done. Rebuild all four calipers with new seals, new fluid, check pads and rotors for damage. I've never seen a sever brake overheat that didn't kill the caliper rubber parts or fluid.

Some think they can just let it cool down and go at it again. Nope. It's like burning the cookies in the oven. Throw out that batch, start over.

If the internal piston seals melted or deformed from heat, the piston would show at minimum some fluid dampness or leak on every pump. There were no signs of leaking so the internals should be good to go.

Originally Posted by ZMEnow

We don't know what the out come of the RR bleed was at the Dealership with the GM Tech support assist because he has never answered how they got it to bleed other than they did. I personally ran my Dot 3 fluid 5 20 min track session before I boiled with complete loss of brakes, hand break only.. i blead the next day with Dot 4 and they continue to work great. I have watched several other Zl1's and 1Le's do the same with no problem.

I had the pleasure this summer of spending sometime on Woodward talking with one of the Brembo designers on the ZL1 system regarding Brembo Pads vs. Hawks. He was telling me they were out West testing Hawk Pads on that system and were literally melting the pads on the cars, and there was no damage to the caliper. So while its certainly possible to damage a boot seal, it would be my last plan of action on this particular setup.

All they had to do is run the 2010 Corvette bleed off the USB plug in to do a complete bleed and cycle the ABS pump. If they don't have that or you are at an independent with a high end SnapOn or similar tool with a full subscription service, they can do it as well.

I have been telling people for years that the OEM pads are the best combination street light duty track pad I have seen on a production car. Unless you are moving to a dedicated hard core track pad, the OEM Brembo pads are very good.

[Aliveguy5]

Originally Posted by Thor142

Not trying to argue here but I've never heard of brake pads getting "greasy" unless they weren't bedded and you get a layer of hot gasses between the pad and the rotor. How do pads get greasy? I'm willing to learn.

By "greasy" I basically meant you lose some braking power as if the pads feel like they could be a little wet.

[Thor142]

Originally Posted by Aliveguy5

By "greasy" I basically meant you lose some braking power as if the pads feel like they could be a little wet.

I was only asking cause I've never actually felt a soft brake pedal on the track. I've only tracked Watkins Glen though and I'm assuming it's because the track is fast and long and the brakes can adequately cool between heavy use. I have a heat gun and see temps of about 900 degrees on the rotors when I pit in. I'm stock except for the motul 600 and true track pads.
I always thought spongy pedals were from boiling fluid. I didn't know a good race pad could actually get "soft" from heat.