C7 Brakes Issues at the Track
07-01-2014, 07:48 AM
#1
Burning Brakes
Thread Starter
C7 Brakes Issues at the Track
I posted on the C7 Forum which doesn't seem to be full of racers, an issue I am having with my car's brakes. Seeing if anybody here can help, it is going into the dealer tomorrow to be looked at.
I finally got the chance to drive my Corvette on the track, prior to going I did all of the logical things to prepare the stock system.
1. I replaced the stock fluids with high temp Dot 4 brake fluid 683 rated from MTI racing.
2. I put in my cooling rings
3. Changed out the pads to Carbotech XP20 all around.
4. Installed Spiegler Stainless lines
I was at Road America and did 2 laps and started hearing a sizzling sound from the brakes, and then noticed the pedal getting soft. I pulled in and looked at my brakes and I had brake fluid coming out of all 4 calipers bleeder valves, of course it wrecked the paint on the calipers.
I was really puzzled so we bled the brakes and used new brake flud, and torqued the bleeders to the factory spec. I went out again and 2 laps later I can hear the sizzling again. I pulled and the same thing was happening the fluid was coming out of the bleeders.
Let me first say I have been driving on a track for 15 years and know how to use my brakes, this was my first time out and I wanted to get to know the car so I was taking it fairly easy. This was at Road America and it is extremely fast but without a doubt this was the craziest thing I have ever seen and extremely disappointing.
I can't figure out how the fluid would come out the bleeders, and how it possibly got hot enough to boil that high of temp fluid.
I finally got the chance to drive my Corvette on the track, prior to going I did all of the logical things to prepare the stock system.
1. I replaced the stock fluids with high temp Dot 4 brake fluid 683 rated from MTI racing.
2. I put in my cooling rings
3. Changed out the pads to Carbotech XP20 all around.
4. Installed Spiegler Stainless lines
I was at Road America and did 2 laps and started hearing a sizzling sound from the brakes, and then noticed the pedal getting soft. I pulled in and looked at my brakes and I had brake fluid coming out of all 4 calipers bleeder valves, of course it wrecked the paint on the calipers.
I was really puzzled so we bled the brakes and used new brake flud, and torqued the bleeders to the factory spec. I went out again and 2 laps later I can hear the sizzling again. I pulled and the same thing was happening the fluid was coming out of the bleeders.
Let me first say I have been driving on a track for 15 years and know how to use my brakes, this was my first time out and I wanted to get to know the car so I was taking it fairly easy. This was at Road America and it is extremely fast but without a doubt this was the craziest thing I have ever seen and extremely disappointing.
I can't figure out how the fluid would come out the bleeders, and how it possibly got hot enough to boil that high of temp fluid.
07-01-2014, 08:21 AM
#2
Instructor
sorry about your mishap.
What about your rotors ? are they purple and blue?
may I ask the obvious question, was the pad dragging the rotor?
did you take the pads out and inpsect the boot around the caliper pistons after the failure?
What about your rotors ? are they purple and blue?
may I ask the obvious question, was the pad dragging the rotor?
did you take the pads out and inpsect the boot around the caliper pistons after the failure?
07-01-2014, 08:26 AM
#3
Burning Brakes
Thread Starter
Rotors looked completely normal, the dust boots also looked good. I literally did two circuits at Road America and was probably only driving 7/10's. Certainly not the way I want to drive this car on the track. Three high speed straights though where I see 150 plus mph.
07-01-2014, 08:45 AM
#4
Sounds like another GM recall for defective bleed screws. No way fluid should be coming out of them, even if you did get them hot enough to boil the fluid. Did the bleeders feel normal when you opened and closed them? Solid pedal before going out on track?
07-01-2014, 08:50 AM
#5
Drifting
not sure you boiled anything. if the bleeders are leaking, they are sucking air in when you let off the brake pedal. when you press the pedal, you are pushing fluid and air back out. problem is the bleeders not the fluid.
07-01-2014, 10:26 AM
#7
Burning Brakes
Thread Starter
http://forums.corvetteforum.com/c6-c...er-screws.html
Maybe get a set of speed bleeder to eliminate the potential defected GM's bleeder screws
Maybe get a set of speed bleeder to eliminate the potential defected GM's bleeder screws
07-01-2014, 11:02 AM
#9
Burning Brakes
Thread Starter
07-01-2014, 02:41 PM
#10
Supporting Vendor
I've dealt with a whole bunch of customers on C7 brakes, and this issue is a new one to me. Out of curiosity, what is the OEM torque spec on the bleed screws (we already sold our C7, so I can't check myself)?
A stupid question, and I'm not trying to question your technical ability, but did you bleed both screws on all four calipers (8 total...four inboard, four outboard on each caliper). I've had customers that weren't even aware there were bleed screws on the inboard caliper half.
Did you completely remove any of the bleed screws and look into the area where they are seating? If a bleed screw isn't seating properly it leaks. For example, if there was any kind of debris in there, etc. it could prevent a proper seal. Obviously if you never removed them, it's unlikely they were contaminated by you, and more likely that these particular calipers weren't manufactured properly.
With proper torquing of the bleed screws, we've never seen the need for any type of sealant. That's at the top levels of professional racing.
As for boiling, the fluid would not have had to boil to come out of the bleed screws if they weren't sealed properly. If they are leaking, any moderate amount of pressure can force fluid out of them...even sitting idle. Your discs and calipers were certainly hot enough after two easy laps that even pouring a little cool liquid onto them would make the liquid sizzle instantly.
I'd say the issue is one of these:
One other little tip...when you are done bleeding your brakes, blow the little bit of residual brake fluid in the tip of the bleed screw out with some brake clean. That way it won't trickle out and mangle your calipers when you heat them up...which does happen.
Hopefully that is helpful.
07-01-2014, 03:14 PM
#11
Burning Brakes
Thread Starter
That is complete nonsense! Definitely don't let them try to pull that one on you. As you said, the brake lines have nothing to do with the bleed screws!
I've dealt with a whole bunch of customers on C7 brakes, and this issue is a new one to me. Out of curiosity, what is the OEM torque spec on the bleed screws (we already sold our C7, so I can't check myself)?
A stupid question, and I'm not trying to question your technical ability, but did you bleed both screws on all four calipers (8 total...four inboard, four outboard on each caliper). I've had customers that weren't even aware there were bleed screws on the inboard caliper half.
Did you completely remove any of the bleed screws and look into the area where they are seating? If a bleed screw isn't seating properly it leaks. For example, if there was any kind of debris in there, etc. it could prevent a proper seal. Obviously if you never removed them, it's unlikely they were contaminated by you, and more likely that these particular calipers weren't manufactured properly.
With proper torquing of the bleed screws, we've never seen the need for any type of sealant. That's at the top levels of professional racing.
As for boiling, the fluid would not have had to boil to come out of the bleed screws if they weren't sealed properly. If they are leaking, any moderate amount of pressure can force fluid out of them...even sitting idle. Your discs and calipers were certainly hot enough after two easy laps that even pouring a little cool liquid onto them would make the liquid sizzle instantly.
I'd say the issue is one of these:
One other little tip...when you are done bleeding your brakes, blow the little bit of residual brake fluid in the tip of the bleed screw out with some brake clean. That way it won't trickle out and mangle your calipers when you heat them up...which does happen.
Hopefully that is helpful.
I've dealt with a whole bunch of customers on C7 brakes, and this issue is a new one to me. Out of curiosity, what is the OEM torque spec on the bleed screws (we already sold our C7, so I can't check myself)?
A stupid question, and I'm not trying to question your technical ability, but did you bleed both screws on all four calipers (8 total...four inboard, four outboard on each caliper). I've had customers that weren't even aware there were bleed screws on the inboard caliper half.
Did you completely remove any of the bleed screws and look into the area where they are seating? If a bleed screw isn't seating properly it leaks. For example, if there was any kind of debris in there, etc. it could prevent a proper seal. Obviously if you never removed them, it's unlikely they were contaminated by you, and more likely that these particular calipers weren't manufactured properly.
With proper torquing of the bleed screws, we've never seen the need for any type of sealant. That's at the top levels of professional racing.
As for boiling, the fluid would not have had to boil to come out of the bleed screws if they weren't sealed properly. If they are leaking, any moderate amount of pressure can force fluid out of them...even sitting idle. Your discs and calipers were certainly hot enough after two easy laps that even pouring a little cool liquid onto them would make the liquid sizzle instantly.
I'd say the issue is one of these:
One other little tip...when you are done bleeding your brakes, blow the little bit of residual brake fluid in the tip of the bleed screw out with some brake clean. That way it won't trickle out and mangle your calipers when you heat them up...which does happen.
Hopefully that is helpful.
to answer your questions
1. Yes all bleeders were bled on the original bleed, the car's brakes were n't done by me they were done by Kelly Moss Motorsports in Madison a very highly respected professional race shop. George the Service Manager did the bleed who is an SCCA racer. Brembo brakes are not foriegn to him in any way. So incompetence is not the issue.
2. The second bleed was done at the track by another Corvette racing team who also used factory torque spec's 116 In/lbs of torque. Again all 8 bleeders were bled in the proper order. The problem happened again.
Literally every corner at the track you would brake and hear the sizzle of brake fluid coming out, It happened on all four Calipers.
07-01-2014, 04:29 PM
#13
Supporting Vendor
Thanks for the insight, my stainless lines came from Essex actually.
to answer your questions
1. Yes all bleeders were bled on the original bleed, the car's brakes were n't done by me they were done by Kelly Moss Motorsports in Madison a very highly respected professional race shop. George the Service Manager did the bleed who is an SCCA racer. Brembo brakes are not foriegn to him in any way. So incompetence is not the issue.
2. The second bleed was done at the track by another Corvette racing team who also used factory torque spec's 116 In/lbs of torque. Again all 8 bleeders were bled in the proper order. The problem happened again.
Literally every corner at the track you would brake and hear the sizzle of brake fluid coming out, It happened on all four Calipers.
to answer your questions
1. Yes all bleeders were bled on the original bleed, the car's brakes were n't done by me they were done by Kelly Moss Motorsports in Madison a very highly respected professional race shop. George the Service Manager did the bleed who is an SCCA racer. Brembo brakes are not foriegn to him in any way. So incompetence is not the issue.
2. The second bleed was done at the track by another Corvette racing team who also used factory torque spec's 116 In/lbs of torque. Again all 8 bleeders were bled in the proper order. The problem happened again.
Literally every corner at the track you would brake and hear the sizzle of brake fluid coming out, It happened on all four Calipers.
Please understand that I'm in no way accusing anyone of incompetence...just trying to clearly understand what exactly happened. I've been asked some amazing questions over the years that you'd hardly believe. My personal favorite..."Which stops better, the red or the black calipers?"
Back to the topic at hand...There are not a lot of possibilities with this situation. The bleed screws are a rather isolated piece of the brake system. Either the screws themselves are not functioning properly, or the area of the caliper where they seat/seal has a problem that won't allow them to seat properly. The fact that the same thing happened on all of your bleed screws at all four corners is basically unheard of. The odds of a random failure on all of those parts at the same time are astronomical. That points to either A) Improper install/torque (which is why I asked the above questions, which you've ruled out), or B) A defect in either the bleed screws themselves, or the calipers on your car. There's really not much else it could be.
As the car sits now parked...can you stand on the brake pedal without any fluid coming out of the bleed screws?
I'd recommending trying some new OEM bleed screws (not aftermarket...you don't want to introduce any additional variables). If possible, you may want to buy a few and try this on your own. Based on the dealership's comments about the relationship of the brake lines to the bleed screws, they either A) Don't know anything about brakes, or B) Are looking for a good reason not to cover your damages.
I'd also remove a couple of the bleed screws and get a peek (and take some pictures) of the seats where the bleed screws sit inside the calipers. Some pics of the bottoms of the bleed screws themselves would also be good. Sometimes you can actually see from witness marks on the bleed screws themselves how they are seating inside the caliper, and if they are sealing properly or not. It only takes very small problems with bleed screws to prevent them from sealing properly.
I'll see if I can dig up some pics to show you what I'm talking about. Again, I'd recommend getting pics of the bleed screws and the area where they sit inside the caliper.
Last edited by JRitt@essex; 07-01-2014 at 04:38 PM. Reason: added info
07-01-2014, 08:10 PM
#14
Burning Brakes
Thread Starter
Understood. We are the exclusive distributor for Spiegler lines, so I knew the lines came from us.
Please understand that I'm in no way accusing anyone of incompetence...just trying to clearly understand what exactly happened. I've been asked some amazing questions over the years that you'd hardly believe. My personal favorite..."Which stops better, the red or the black calipers?"
Back to the topic at hand...There are not a lot of possibilities with this situation. The bleed screws are a rather isolated piece of the brake system. Either the screws themselves are not functioning properly, or the area of the caliper where they seat/seal has a problem that won't allow them to seat properly. The fact that the same thing happened on all of your bleed screws at all four corners is basically unheard of. The odds of a random failure on all of those parts at the same time are astronomical. That points to either A) Improper install/torque (which is why I asked the above questions, which you've ruled out), or B) A defect in either the bleed screws themselves, or the calipers on your car. There's really not much else it could be.
As the car sits now parked...can you stand on the brake pedal without any fluid coming out of the bleed screws?
I'd recommending trying some new OEM bleed screws (not aftermarket...you don't want to introduce any additional variables). If possible, you may want to buy a few and try this on your own. Based on the dealership's comments about the relationship of the brake lines to the bleed screws, they either A) Don't know anything about brakes, or B) Are looking for a good reason not to cover your damages.
I'd also remove a couple of the bleed screws and get a peek (and take some pictures) of the seats where the bleed screws sit inside the calipers. Some pics of the bottoms of the bleed screws themselves would also be good. Sometimes you can actually see from witness marks on the bleed screws themselves how they are seating inside the caliper, and if they are sealing properly or not. It only takes very small problems with bleed screws to prevent them from sealing properly.
I'll see if I can dig up some pics to show you what I'm talking about. Again, I'd recommend getting pics of the bleed screws and the area where they sit inside the caliper.
Please understand that I'm in no way accusing anyone of incompetence...just trying to clearly understand what exactly happened. I've been asked some amazing questions over the years that you'd hardly believe. My personal favorite..."Which stops better, the red or the black calipers?"
Back to the topic at hand...There are not a lot of possibilities with this situation. The bleed screws are a rather isolated piece of the brake system. Either the screws themselves are not functioning properly, or the area of the caliper where they seat/seal has a problem that won't allow them to seat properly. The fact that the same thing happened on all of your bleed screws at all four corners is basically unheard of. The odds of a random failure on all of those parts at the same time are astronomical. That points to either A) Improper install/torque (which is why I asked the above questions, which you've ruled out), or B) A defect in either the bleed screws themselves, or the calipers on your car. There's really not much else it could be.
As the car sits now parked...can you stand on the brake pedal without any fluid coming out of the bleed screws?
I'd recommending trying some new OEM bleed screws (not aftermarket...you don't want to introduce any additional variables). If possible, you may want to buy a few and try this on your own. Based on the dealership's comments about the relationship of the brake lines to the bleed screws, they either A) Don't know anything about brakes, or B) Are looking for a good reason not to cover your damages.
I'd also remove a couple of the bleed screws and get a peek (and take some pictures) of the seats where the bleed screws sit inside the calipers. Some pics of the bottoms of the bleed screws themselves would also be good. Sometimes you can actually see from witness marks on the bleed screws themselves how they are seating inside the caliper, and if they are sealing properly or not. It only takes very small problems with bleed screws to prevent them from sealing properly.
I'll see if I can dig up some pics to show you what I'm talking about. Again, I'd recommend getting pics of the bleed screws and the area where they sit inside the caliper.
Either way my new calipers are ruined, they should be replaced.
07-02-2014, 07:00 AM
#17
C7
In my first race with the C7 it has a simple yet rained.,
Brake, etc. everything has worked perfectly.
Second race, it was 25 ° down dry and slick.
After about 20 minutes I had to stop.
Brakes complete failure due to heat and water cooling motor ...
We are at work for the future to solve the problem
Cölestin
Brake, etc. everything has worked perfectly.
Second race, it was 25 ° down dry and slick.
After about 20 minutes I had to stop.
Brakes complete failure due to heat and water cooling motor ...
We are at work for the future to solve the problem
Cölestin
07-02-2014, 08:36 AM
#18
Supporting Vendor
The car has 1500 miles on it, and the only driving done on the car has been light driving up until the track event, under normal conditions the bleeders and not leaking. Hard for me to imagine that a brand new car has debris in the bleeders on all four wheels, unless it was painted or something inside the bleeder holes and that is dislodging.
Either way my new calipers are ruined, they should be replaced.
Either way my new calipers are ruined, they should be replaced.
I'm not sure if I missed your answer... Can you make the bleeders leak if the car is sitting idle and you stand on the brake pedal? Also, how much fluid actually leaked out? Was it an amount that required you to top off your reservoir with brake fluid, or just a small trickle? Thanks.
07-02-2014, 11:24 AM
#19
Burning Brakes
Thread Starter
Dealer want to replace bleeders to start, not sure how to test other than on the track though.
They are talking about replacing the calipers, but unsure how to prove the failure other than the missing paint on the caliper.
They are talking about replacing the calipers, but unsure how to prove the failure other than the missing paint on the caliper.
07-02-2014, 11:27 AM
#20
Burning Brakes
Thread Starter
That was exactly my point. It wouldn't be outside debris in the bleeders, but it could be paint, etc. dislodging and mucking things up.
I'm not sure if I missed your answer... Can you make the bleeders leak if the car is sitting idle and you stand on the brake pedal? Also, how much fluid actually leaked out? Was it an amount that required you to top off your reservoir with brake fluid, or just a small trickle? Thanks.
I'm not sure if I missed your answer... Can you make the bleeders leak if the car is sitting idle and you stand on the brake pedal? Also, how much fluid actually leaked out? Was it an amount that required you to top off your reservoir with brake fluid, or just a small trickle? Thanks.
I suspected paint as well when I spoke with the dealer today. If you were to paint the caliper and get some in the chases I would think that could have some adverse effects if it started to come off.
The leak was enough to remove some dime shaped areas of paint after doing a full lap with it leaking out it did lower the brake fluid levels slightly.
