[ANSWERED] Track day brake failures and warranty
02-03-2017, 04:10 PM
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[ANSWERED] Track day brake failures and warranty
The original question is here.
RS4EVA asked:
Many customers are reporting brake fluid leaking out of the bleed screws during track events... The brake fluid appears like it's being pushed out from the outer bleed screw, which introduces air into the system causing the fluid to boil, and the brakes to go away quickly. The inner screw and caliper seem to be largely unaffected and stay clean.
Since this is only able to be reproduced under track conditions, the dealers aren't able to diagnose or fix it. Can someone from your engineering team help by investigating the issue, diagnosing the problem and coming up with a resolution.
Many customers are reporting brake fluid leaking out of the bleed screws during track events... The brake fluid appears like it's being pushed out from the outer bleed screw, which introduces air into the system causing the fluid to boil, and the brakes to go away quickly. The inner screw and caliper seem to be largely unaffected and stay clean.
Since this is only able to be reproduced under track conditions, the dealers aren't able to diagnose or fix it. Can someone from your engineering team help by investigating the issue, diagnosing the problem and coming up with a resolution.
Tadge answered:
Many of the questions I get on this forum are from track folks who exercise their Corvette to the limit of its performance. We are very happy that people are using that capability and for the most part, there are very few problems. Our service folks and Brembo engineers regularly monitor vehicles being used on track. Properly prepared, we have had minimal issues with brake fluid leaks through the bleeder screws.
Since many people read my answers to these questions, I have to answer to a larger crowd, not just you, the specific questioner, RS4EVA. So I will include vehicle prep basics for everyone and I don't want you to be insulted, like I'm assuming you don't know what you are doing.
Although it is not always a popular answer, I can only testify to the performance of stock vehicles. We do our validation on factory spec cars. There is no way to account for the performance of the infinite number of after-market components. I talk to customers every day who swear their car is stock because they don't consider the use of slicks, racing coolant, or race brake pads to be modifications. Same with new shocks, trim height changes or alignment specs outside what is recommended in the owner’s manual. Even mixing and matching factory parts can lead to issues such as putting up-level aerodynamic components on a car with standard brakes. Adding downforce or tampering with brake cooling airflow can lead to reduced performance. Both tires and alternative pads can impact brake performance substantially. Neither Brembo nor GM can be responsible for the performance of other pad materials. Racing materials can cause elevated fluid temperatures (even boil) and accelerated rotor wear and heat checking, to say nothing of the adverse impact on the ABS and stability control calibrations.
Regarding the ‘weeping’ of bleeder screws: Typically that is the result of the person servicing the caliper not evacuating the small column of fluid (maybe 0.2cc) that remains in the bleeder after tightening. In road use this is a nonissue, but if the vehicle is taken to the track and the caliper gets hot, the fluid can expand and seep out.
The bleeder screw design and caliper interface (seat/port geometry) is nearly universal in Brembo aluminum calipers (including Brembo’s racing products) so it’s likely not design issue. Calipers are 100% leak tested for low pressure, high pressure and vacuum, both before and after painting. The bleeder screws must be properly torqued and only when the caliper is cool (very important even though it may seem like a minor thing). Keep in mind torque values are different between two-piece calipers (like JL9/J55) and monoblock calipers (J56/J57 front). Proper torque of bridge bolts in six-piston calipers that use them is also important. A squirt of compressed air or brake cleaner on the bleeder is a good idea after bleeding to purge any residual fluid that might weep.
Approved brake fluid must be used, appropriate for the intended usage (meaning DOT4 for track use). Some customers use racing fluids (Castrol SRF, Motul 600, etc) which have not been tested by GM or Brembo for seal compatibility with caliper, master cylinder or ABS unit. When replacing existing brake fluid with a qualified high performance brake fluid it must come from a sealed container. Brake fluid with a dry boiling point >279 °C (534 °F) is qualified. If high performance brake fluid is used, replace it with GM approved brake fluid before driving on public roads. If high performance brake fluid is in the vehicle and the age of the brake fluid is over a month old or unknown, replace the brake fluid before track events and competitive driving. Do not use silicone or DOT-5 brake fluids.
Finally it is always a good idea after any severe usage, to inspect dust boots and replace as necessary. Very hot temperatures can cause cracking or, in extreme cases, dust boot melting.
Thank you for the question RS4EVA. We are always interested in learning more about out hardware performance in the field. Brembo is an elite brake manufacturer, and like us, we are always interested in continuous improvement.
Many of the questions I get on this forum are from track folks who exercise their Corvette to the limit of its performance. We are very happy that people are using that capability and for the most part, there are very few problems. Our service folks and Brembo engineers regularly monitor vehicles being used on track. Properly prepared, we have had minimal issues with brake fluid leaks through the bleeder screws.
Since many people read my answers to these questions, I have to answer to a larger crowd, not just you, the specific questioner, RS4EVA. So I will include vehicle prep basics for everyone and I don't want you to be insulted, like I'm assuming you don't know what you are doing.
Although it is not always a popular answer, I can only testify to the performance of stock vehicles. We do our validation on factory spec cars. There is no way to account for the performance of the infinite number of after-market components. I talk to customers every day who swear their car is stock because they don't consider the use of slicks, racing coolant, or race brake pads to be modifications. Same with new shocks, trim height changes or alignment specs outside what is recommended in the owner’s manual. Even mixing and matching factory parts can lead to issues such as putting up-level aerodynamic components on a car with standard brakes. Adding downforce or tampering with brake cooling airflow can lead to reduced performance. Both tires and alternative pads can impact brake performance substantially. Neither Brembo nor GM can be responsible for the performance of other pad materials. Racing materials can cause elevated fluid temperatures (even boil) and accelerated rotor wear and heat checking, to say nothing of the adverse impact on the ABS and stability control calibrations.
Regarding the ‘weeping’ of bleeder screws: Typically that is the result of the person servicing the caliper not evacuating the small column of fluid (maybe 0.2cc) that remains in the bleeder after tightening. In road use this is a nonissue, but if the vehicle is taken to the track and the caliper gets hot, the fluid can expand and seep out.
The bleeder screw design and caliper interface (seat/port geometry) is nearly universal in Brembo aluminum calipers (including Brembo’s racing products) so it’s likely not design issue. Calipers are 100% leak tested for low pressure, high pressure and vacuum, both before and after painting. The bleeder screws must be properly torqued and only when the caliper is cool (very important even though it may seem like a minor thing). Keep in mind torque values are different between two-piece calipers (like JL9/J55) and monoblock calipers (J56/J57 front). Proper torque of bridge bolts in six-piston calipers that use them is also important. A squirt of compressed air or brake cleaner on the bleeder is a good idea after bleeding to purge any residual fluid that might weep.
Approved brake fluid must be used, appropriate for the intended usage (meaning DOT4 for track use). Some customers use racing fluids (Castrol SRF, Motul 600, etc) which have not been tested by GM or Brembo for seal compatibility with caliper, master cylinder or ABS unit. When replacing existing brake fluid with a qualified high performance brake fluid it must come from a sealed container. Brake fluid with a dry boiling point >279 °C (534 °F) is qualified. If high performance brake fluid is used, replace it with GM approved brake fluid before driving on public roads. If high performance brake fluid is in the vehicle and the age of the brake fluid is over a month old or unknown, replace the brake fluid before track events and competitive driving. Do not use silicone or DOT-5 brake fluids.
Finally it is always a good idea after any severe usage, to inspect dust boots and replace as necessary. Very hot temperatures can cause cracking or, in extreme cases, dust boot melting.
Thank you for the question RS4EVA. We are always interested in learning more about out hardware performance in the field. Brembo is an elite brake manufacturer, and like us, we are always interested in continuous improvement.
02-04-2017, 05:12 PM
#2
Burning Brakes
The original question is here.
JVP, would you mind submitting this followup question
I experienced brake fluid loss while at the track with brand new OEM pads, rotors, and calipers, flushed with DOT4 fluid all done at the dealership by a Corvette specialist. My claim was denied because the technician and service manager could not replicate the issue on the street. But there is plenty of physical evidence to show that it in fact did happen.
Should the caliper be replaced under warranty, Yes or No?
02-04-2017, 06:59 PM
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02-04-2017, 11:50 PM
#4
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Tadge, thanks for the response. It's what I expected, but not what I was hoping for. To be clear, you are saying there is no way the fluid is coming out of the bleed screw thread, not the tip. This is the critical point of difference.
JVP, would you mind submitting this followup question
I experienced brake fluid loss while at the track with brand new OEM pads, rotors, and calipers, flushed with DOT4 fluid all done at the dealership by a Corvette specialist. My claim was denied because the technician and service manager could not replicate the issue on the street. But there is plenty of physical evidence to show that it in fact did happen.
Should the caliper be replaced under warranty, Yes or No?
JVP, would you mind submitting this followup question
I experienced brake fluid loss while at the track with brand new OEM pads, rotors, and calipers, flushed with DOT4 fluid all done at the dealership by a Corvette specialist. My claim was denied because the technician and service manager could not replicate the issue on the street. But there is plenty of physical evidence to show that it in fact did happen.
Should the caliper be replaced under warranty, Yes or No?
I've seen lots of inconsistent torque values posted as PDF and such on this forum. I've even see a supposedly official PDF with bad math, showing the value as 106 in-lbs, 12 ft-lbs!!!!! 106 in-lbs is not 12 ft-lbs in any nation I've lived! At least not up till today!
I've seen 13-14ft-lbs too. Also the values are different for Z06/GS vs Z51.
Not to mention as Tadge said these values are out the door when caliper is hot. My car is new, so haven't bled it yet, and when I asked a dealer service man this question I didn't get a very convincing response. So I'll be visiting respected race shop, and as long as Brembos are universal for their types, size or models, I'm hoping he will be able to give me an answer I can trust. So don't totally trust your dealer to know the correct torque.
02-05-2017, 09:35 AM
#5
In this case I thought Tadge's response (filtered through corporate speak) was very clear.
The brakes are perfect and tested as delivered. If you change anything you are on your own. If they fail at the track and the dealer does not believe they are defective, you are on your own. A follow up here would get no where so I fully understand why jvp declined to push the point.
The brakes are perfect and tested as delivered. If you change anything you are on your own. If they fail at the track and the dealer does not believe they are defective, you are on your own. A follow up here would get no where so I fully understand why jvp declined to push the point.
02-05-2017, 12:34 PM
#6
I experienced brake fluid loss while at the track with brand new OEM pads, rotors, and calipers, flushed with DOT4 fluid all done at the dealership by a Corvette specialist. My claim was denied because the technician and service manager could not replicate the issue on the street. But there is plenty of physical evidence to show that it in fact did happen.
Ask the service manger if the mechanics are working on the Bonus program? Here's how the Bonus program works. If the flat rate manual says a particular repair should take 2 hours and the mechanic completes the job in 90 minutes, he is paid for 2 hours. As you can imagine there is a huge incentive for the mechanic to rush through the repair, cut corners (bleed not flush, tighten by feel and not use a torque wrench, not cleaning parts, etc), and not double check their work. The last time I took my car in to the dealer was for warranty work. I found plastic covers not attached correctly, a bungee cord, oil and coolant droplets hanging off the bottom of engine parts. How did the mechanic know that these droplets where not from leak? He does not know because he is on the clock for the next repair. I am so glad that my car is no longer under warranty and I can do the work myself.
My point is that just because you took it to the dealer, don't think that work was done per the service manual, or to your expectations, or to the level that a mechanic on a race team would do to a race car, just because you're bring in $100,000+ Corvette. You're going to get the same crappie level of service that someone with a $13,000 Spark is going to get.
Last edited by grcor; 02-05-2017 at 12:50 PM.
02-05-2017, 06:19 PM
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Are you sure that DOT 4 brake fluid was used? How do you know that brake fluid was completely flushed, most likely it was just bleed. What makes you think the mechanic used a torque wrench on the bleeder value? 99.999% of the time they do it by feel. I know that my brake fluid is completely flushed with DOT 4 and the bleeder valves are torqued correctly because I do the work myself and I take my time.
Ask the service manger if the mechanics are working on the Bonus program? Here's how the Bonus program works. If the flat rate manual says a particular repair should take 2 hours and the mechanic completes the job in 90 minutes, he is paid for 2 hours. As you can imagine there is a huge incentive for the mechanic to rush through the repair, cut corners (bleed not flush, tighten by feel and not use a torque wrench, not cleaning parts, etc), and not double check their work. The last time I took my car in to the dealer was for warranty work. I found plastic covers not attached correctly, a bungee cord, oil and coolant droplets hanging off the bottom of engine parts. How did the mechanic know that these droplets where not from leak? He does not know because he is on the clock for the next repair. I am so glad that my car is no longer under warranty and I can do the work myself.
My point is that just because you took it to the dealer, don't think that work was done per the service manual, or to your expectations, or to the level that a mechanic on a race team would do to a race car, just because you're bring in $100,000+ Corvette. You're going to get the same crappie level of service that someone with a $13,000 Spark is going to get.
Ask the service manger if the mechanics are working on the Bonus program? Here's how the Bonus program works. If the flat rate manual says a particular repair should take 2 hours and the mechanic completes the job in 90 minutes, he is paid for 2 hours. As you can imagine there is a huge incentive for the mechanic to rush through the repair, cut corners (bleed not flush, tighten by feel and not use a torque wrench, not cleaning parts, etc), and not double check their work. The last time I took my car in to the dealer was for warranty work. I found plastic covers not attached correctly, a bungee cord, oil and coolant droplets hanging off the bottom of engine parts. How did the mechanic know that these droplets where not from leak? He does not know because he is on the clock for the next repair. I am so glad that my car is no longer under warranty and I can do the work myself.
My point is that just because you took it to the dealer, don't think that work was done per the service manual, or to your expectations, or to the level that a mechanic on a race team would do to a race car, just because you're bring in $100,000+ Corvette. You're going to get the same crappie level of service that someone with a $13,000 Spark is going to get.
I always recommend repair shops where the techs are paid by the hour only. The incentive is more likely then to do things right first, efficiency second. I know we have 10 of them!The answer from Tadge doesn't surprise me either although I sure hope it causes GM to help out the OP as they can in special circumstances. Good luck fellow track rat
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Thejoyofdriving (06-14-2017)
02-06-2017, 08:32 PM
#9
Burning Brakes
In this case I thought Tadge's response (filtered through corporate speak) was very clear.
The brakes are perfect and tested as delivered. If you change anything you are on your own. If they fail at the track and the dealer does not believe they are defective, you are on your own. A follow up here would get no where so I fully understand why jvp declined to push the point.
The brakes are perfect and tested as delivered. If you change anything you are on your own. If they fail at the track and the dealer does not believe they are defective, you are on your own. A follow up here would get no where so I fully understand why jvp declined to push the point.
I totally understand modifying components leaves me holding the bag. I am questioning what happens when you don't change anything from stock, and still have issues. Seems we're still out of luck if it only happens at the track, even though there is physical evidence of a problem.
Just so we are all on the same page.
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Thejoyofdriving (06-14-2017)
02-08-2017, 07:57 PM
#10
Team Owner
Pro Mechanic
The following 2 users liked this post by Tom400CFI:
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Thejoyofdriving (06-14-2017)
02-08-2017, 08:28 PM
#11
Burning Brakes