Braking failure at track today
Race Director
Joined: Aug 1999
Posts: 13,300
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From: Bluffton SC via Canton Oh
Dumb ? on my part... not to hijack the thread. Why would I not run Dot 4 all the time..... and if so why does gm not put in Dot4?
I'm about ready to start track season in Ohio and this is an eye opener.
Glad you all and the car seems OK!!
I'm about ready to start track season in Ohio and this is an eye opener.
Glad you all and the car seems OK!!
Race Director
Joined: Jan 2000
Posts: 12,375
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From: Florida
Last edited by TTRotary; May 8, 2014 at 02:09 PM.
Team Owner
Joined: May 2005
Posts: 20,209
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From: NY
St. Jude Donor '26
What brake fluid is in the car?
It sounds like the fluid boiled, especially since "pumping" the brakes brought them back somewhat. Bear in mind, under braking pressure, fluid often doesn't boil...it's when you're off the brakes and the pressure is lower that it boils in the caliper.
Some tracks you can get away with a stock temp fluid, some tracks you can't. I ran stock fluid at Daytona, but wouldn't consider running stock fluid at Sebring, Homestead or RA. This could have happened in a few laps because the fluid, because it's hygroscopic, had a decreased boiling point.
S.
It sounds like the fluid boiled, especially since "pumping" the brakes brought them back somewhat. Bear in mind, under braking pressure, fluid often doesn't boil...it's when you're off the brakes and the pressure is lower that it boils in the caliper.
Some tracks you can get away with a stock temp fluid, some tracks you can't. I ran stock fluid at Daytona, but wouldn't consider running stock fluid at Sebring, Homestead or RA. This could have happened in a few laps because the fluid, because it's hygroscopic, had a decreased boiling point.
S.
Thread Starter
Pro
Joined: Jan 2000
Posts: 745
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From: Anaheim Hills, Calif.
The car is Stock. My buddy the driver, has over 500+ laps on this track, he has been involved in racing since the mid 80s. He is one of the very few people I would ever allow to drive my car on a track.
I honestly think there was some kind of electronic issue going on. The brake was rock solid when he pushed on the brake and shifted from 4th to third. The brake felt like when the car is off. There was also no rev match when shifting from 4th to 3rd. He held the clutch in and once we hit the dirt began to pump the brakes and they came back. The where not mush, or faded. It was as if the rev match and brakes thought the car was off.
I honestly think there was some kind of electronic issue going on. The brake was rock solid when he pushed on the brake and shifted from 4th to third. The brake felt like when the car is off. There was also no rev match when shifting from 4th to 3rd. He held the clutch in and once we hit the dirt began to pump the brakes and they came back. The where not mush, or faded. It was as if the rev match and brakes thought the car was off.
Drifting
Joined: Mar 2011
Posts: 1,519
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From: Indy
I understand that the brakes might have malfunctions, but he didn't even try to make the turn... He went strait? Did the electronic steering go out as well? To his defense he started screaming the brakes went out the moment he didn't make the turn
Melting Slicks
Joined: May 2001
Posts: 2,596
Likes: 120
From: East Tennessee
Its possible vacuum reservoir for the power brakes was exhausted and the auxiliary vacuum pump failed to turn on or didnt work and there was no power brakes. Or he just found the right combination of throttle/downshift to mess up the system.
There is no real on or off with the power brakes, the power assist uses engine vacuum and when accelerating there is no engine vacuum, decelerating there is plenty. These cars have an auxiliary pump (silver cylinder on the LH side by the brake master cyl) to supply vacuum if there isnt enough from the engine, pretty common these days.
Its possible, but with no assist there still is some braking if you really push the pedal hard, but going that fast its easy to think the brakes are out if the power assist is gone.
The way the ABS is set up there is no way the the ABS can completely shut down braking on all four wheels, well thats how its designed anyhow..
There is no real on or off with the power brakes, the power assist uses engine vacuum and when accelerating there is no engine vacuum, decelerating there is plenty. These cars have an auxiliary pump (silver cylinder on the LH side by the brake master cyl) to supply vacuum if there isnt enough from the engine, pretty common these days.
Its possible, but with no assist there still is some braking if you really push the pedal hard, but going that fast its easy to think the brakes are out if the power assist is gone.
The way the ABS is set up there is no way the the ABS can completely shut down braking on all four wheels, well thats how its designed anyhow..
Racer
Joined: Oct 2012
Posts: 372
Likes: 0
First off glad you and your driver is alright... Glad to here the stingray is in good working order that could of been real bad real bad... As far as making a turn at 90+MPH without brakes I would think that if you tried to turn you could of made the off track experience even worse. ... Hope you get to the bottom of this.
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Intermediate
Joined: May 2012
Posts: 33
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From: San Francisco CA
Ice mode? I've almost gone off at Thunderhill and Buttonwillow in a C6 Z06 because the pedal goes completely hard for no apparent reason. It's a very helpless feeling. I have Castrol SRF and XP12/10 pads...
Race Director
Joined: Aug 2000
Posts: 17,992
Likes: 280
I'm sorry to hear about your car. i havent watched the video yet, but my suggestion may raise an eyebrow. Go back out and reproduce the issue.
we get nowhere fast taking a car to the stealer with a problem we cant replicate and a problem that requires a racetrack. what is the tech going to do to diagnose something like this? GM does not provide stealers what they need to fix issues like this.
once your buddy nails the steps to reproduce the problem, you can try it as well as the stealer. Doing this removes any question about the drivers skills and abilities handling a car of that caliber. further, you will be able to verify if the brakes are fixed when the stealer says its fixed.
we get nowhere fast taking a car to the stealer with a problem we cant replicate and a problem that requires a racetrack. what is the tech going to do to diagnose something like this? GM does not provide stealers what they need to fix issues like this.
once your buddy nails the steps to reproduce the problem, you can try it as well as the stealer. Doing this removes any question about the drivers skills and abilities handling a car of that caliber. further, you will be able to verify if the brakes are fixed when the stealer says its fixed.
Last edited by C5 Hardtop; May 10, 2014 at 01:56 PM.
Race Director
Joined: Aug 2000
Posts: 17,992
Likes: 280
I'm sorry to hear about your car. i havent watched the video yet, but my suggestion may raise an eyebrow. Go back out and reproduce the issue.
we get nowhere fast taking a car to the stealer with a problem we cant replicate and a problem that requires a racetrack. what is the tech going to do to diagnose something like this? GM does not provide stealers what they need to fix issues like this.
once your buddy nails the steps to reproduce the problem, you can try it as well as the stealer. Doing this removes any question about the drivers skills and abilities handling a car of that caliber. further, you will be able to verify if the brakes are fixed when the stealer says its fixed.
we get nowhere fast taking a car to the stealer with a problem we cant replicate and a problem that requires a racetrack. what is the tech going to do to diagnose something like this? GM does not provide stealers what they need to fix issues like this.
once your buddy nails the steps to reproduce the problem, you can try it as well as the stealer. Doing this removes any question about the drivers skills and abilities handling a car of that caliber. further, you will be able to verify if the brakes are fixed when the stealer says its fixed.
I have a history of tracking corvettes and when I was at my peak experience level I tracked 2-4 events per month in my vettes until the seasons ended. I can listen to a coach and WILL do what he says if I think he knows his ****. I've also paid for coaching by racing professionals, one of which became my mentor (and he held a trans am track record at SIR).
After watching the video there were a few factors that push me away from the car having a braking failure to wanting to know more about his driving history. How many times has he driven off the track prior too turn in?
He sped up significantly after passing the camaro. That was quite entertaining and for a moment it looked so fun! However, after passing that camaro he may have felt obligated to maintain that *huge* incremental jump in pace so he doesn't slow down the camaro right after passing it. He is in a new car that he doesn't know and it isn't his. Could these factors put him well out of his comfort zone? Could he have mitigated risk (got cold feet) by driving off instead of completing turn-in? It did look like the vette slowed down quite a bit before following the skid marks off the track. I've never been on that track. Was he going slow enough to complete turn in when he flinched the wheel?
Thread Starter
Pro
Joined: Jan 2000
Posts: 745
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From: Anaheim Hills, Calif.
Hearing the drivers experience and the lousy quality control Chevy has had gave me confidence the car had a problem.
I have a history of tracking corvettes and when I was at my peak experience level I tracked 2-4 events per month in my vettes until the seasons ended. I can listen to a coach and WILL do what he says if I think he knows his ****. I've also paid for coaching by racing professionals, one of which became my mentor (and he held a trans am track record at SIR).
After watching the video there were a few factors that push me away from the car having a braking failure to wanting to know more about his driving history. How many times has he driven off the track prior too turn in?
He sped up significantly after passing the camaro. That was quite entertaining and for a moment it looked so fun! However, after passing that camaro he may have felt obligated to maintain that *huge* incremental jump in pace so he doesn't slow down the camaro right after passing it. He is in a new car that he doesn't know and it isn't his. Could these factors put him well out of his comfort zone? Could he have mitigated risk (got cold feet) by driving off instead of completing turn-in? It did look like the vette slowed down quite a bit before following the skid marks off the track. I've never been on that track. Was he going slow enough to complete turn in when he flinched the wheel?
I have a history of tracking corvettes and when I was at my peak experience level I tracked 2-4 events per month in my vettes until the seasons ended. I can listen to a coach and WILL do what he says if I think he knows his ****. I've also paid for coaching by racing professionals, one of which became my mentor (and he held a trans am track record at SIR).
After watching the video there were a few factors that push me away from the car having a braking failure to wanting to know more about his driving history. How many times has he driven off the track prior too turn in?
He sped up significantly after passing the camaro. That was quite entertaining and for a moment it looked so fun! However, after passing that camaro he may have felt obligated to maintain that *huge* incremental jump in pace so he doesn't slow down the camaro right after passing it. He is in a new car that he doesn't know and it isn't his. Could these factors put him well out of his comfort zone? Could he have mitigated risk (got cold feet) by driving off instead of completing turn-in? It did look like the vette slowed down quite a bit before following the skid marks off the track. I've never been on that track. Was he going slow enough to complete turn in when he flinched the wheel?
Bottom line is the cars braking system failed. I want to know why. I have been in contact with my dealer since the incident, and have made an appointment to bring the car to my dealer this Monday.
Last edited by VRMMMM; May 10, 2014 at 05:20 PM.
Race Director
Joined: Aug 2000
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The driver, my friend Robert has had many race cars, currenty has a 2008 race prepped Z06. He was going 95mph in a spot I had just driven my C7 in the same spot at 104mph. Roberts skill level is much higher than mine.
Bottom line is the cars braking system failed. I want to know why. I have been in contact with my dealer since the incident, and have made an appointment to bring the car to my dealer this Monday.
Bottom line is the cars braking system failed. I want to know why. I have been in contact with my dealer since the incident, and have made an appointment to bring the car to my dealer this Monday.
Will you post what the dealer says? With luck, there might be a known issue with the brakes and they know how to handle it. The local stealer here said they didn't have any C7's (a couple months ago) because there were quality issues holding up delivery.
Scraping the splitter.
Joined: Jun 2005
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St. Jude Donor '13-'14-'15
I'm still betting the fluid was boiling in the calipers. You don't see it boiling in the reservoir, so there is no way to state it "was not boiling". I doubt the dealer is going to find anything and I would suggest bleeding and filling with DOT4, RBF660, etc..
Good luck.
S.
Good luck.
S.
Race Director
Joined: Aug 2000
Posts: 17,992
Likes: 280
I'm still betting the fluid was boiling in the calipers. You don't see it boiling in the reservoir, so there is no way to state it "was not boiling". I doubt the dealer is going to find anything and I would suggest bleeding and filling with DOT4, RBF660, etc..
Good luck.
S.
Good luck.
S.
I haven't boiled fluid before (Motul baby!) so I don't know first hand what it is like. To repeat 'pit talk', I heard when brake fluid boils the pedal gets mushy after the fluid has cooled off and to fix it, the brake fluid needs to be bled out.
Safety Car
Joined: Aug 2012
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I'm still betting the fluid was boiling in the calipers. You don't see it boiling in the reservoir, so there is no way to state it "was not boiling". I doubt the dealer is going to find anything and I would suggest bleeding and filling with DOT4, RBF660, etc..
Good luck.
S.
Good luck.
S.
I guess if you want to play back yard scientist you can pull a sample of your fluid and actually test the boiling point, I bet you will be surprised at how low it is. Just a little moisture (which happens readily with time) greatly reduces the boiling point and stock fluid has a fairly low boiling point even when fresh.
4th Gear
Joined: May 2014
Posts: 4
Likes: 0
Gotta be the fluid
I took my car to Willow springs today for the first time. I have been to this track several times with other cars, and really enjoy the track. I first went out in my run session, and was amazed at the C7s ability, simply amazing track car! I was in Track mode/Sport.
My friend was there with his 2014 AMG C63, I had noticed he pulled in after 3 laps, I took my car around one more time then came into the pits to see why my buddy came in early. Said the C63 overheated and went into limp mode, this is a car with 2500 miles on a 68 degree day WTF!!
I tell him we still have 10 mins in our run group and to try out the C7, so we take the car out with my friend driving. He does the first lat at about 6/10th to get a feel for everything, 2nd lap he starts pushing a bit harder about 8/10s. Everything is good, no fade, no smells, just running perfect.
On turn 8 which is a long sweeper, we are going about 95mph, we reach the braking zone, my friend hits the brake, and NOTHING! We go straight off the track, not turning, in the dirt. Without taking his foot of the brake he starts to pump the brake pedal, and the brakes come back. He gets the car stopped, we took the car directly to the pits to check it out. Fluid is fine, not boiling, nothing seems wrong.
We talked to other Corvette guys at the track, mechanics at the track, nobody can figure out how this happened. The pedal was firm, so sign of fade. Just no braking zero. We had a GOPro in the car, we are going to review it tonight.
The car is fine, just got dirty. I contacted my dealer, and will bring it in for a full check up, but this seems very bizarre to us. Any thoughts or advice?
My friend was there with his 2014 AMG C63, I had noticed he pulled in after 3 laps, I took my car around one more time then came into the pits to see why my buddy came in early. Said the C63 overheated and went into limp mode, this is a car with 2500 miles on a 68 degree day WTF!!
I tell him we still have 10 mins in our run group and to try out the C7, so we take the car out with my friend driving. He does the first lat at about 6/10th to get a feel for everything, 2nd lap he starts pushing a bit harder about 8/10s. Everything is good, no fade, no smells, just running perfect.
On turn 8 which is a long sweeper, we are going about 95mph, we reach the braking zone, my friend hits the brake, and NOTHING! We go straight off the track, not turning, in the dirt. Without taking his foot of the brake he starts to pump the brake pedal, and the brakes come back. He gets the car stopped, we took the car directly to the pits to check it out. Fluid is fine, not boiling, nothing seems wrong.
We talked to other Corvette guys at the track, mechanics at the track, nobody can figure out how this happened. The pedal was firm, so sign of fade. Just no braking zero. We had a GOPro in the car, we are going to review it tonight.
The car is fine, just got dirty. I contacted my dealer, and will bring it in for a full check up, but this seems very bizarre to us. Any thoughts or advice?
Scraping the splitter.
Joined: Jun 2005
Posts: 8,111
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St. Jude Donor '13-'14-'15
And he reported pumping the brakes caused them to function again which is typical of what happens when fluid boils in the caliper pistons. Without DOT4 or similar high temperature fluid this is what happens under these conditions which is why GM states you must use it for competitive driving. You won't see the fluid boiling in the reservoir, the heat doesn't transfer readily through the fluid. When fluid boils the system is now compressing the gas which was liberated from the fluid instead of applying high force to the pistons.
I guess if you want to play back yard scientist you can pull a sample of your fluid and actually test the boiling point, I bet you will be surprised at how low it is. Just a little moisture (which happens readily with time) greatly reduces the boiling point and stock fluid has a fairly low boiling point even when fresh.
I guess if you want to play back yard scientist you can pull a sample of your fluid and actually test the boiling point, I bet you will be surprised at how low it is. Just a little moisture (which happens readily with time) greatly reduces the boiling point and stock fluid has a fairly low boiling point even when fresh.
The boiling point of ANY brake fluid is severely compromised by the absorption of water, and as we know, brake fluid is highly hygroscopic.
Three weeks ago, I ran my track car at Sebring two weeks after running at Daytona with fresh everything. Brakes were solid all day Saturday with the increased cooling that we installed prior to the Daytona event. Sunday, I was 25 minutes into a session and on T7 I noticed them fade slightly as I was hitting my turn-in. Aware of this, I ran through T8-T9, and lifted early into T10, hitting the brakes at the #4 marker instead of the usual #3 (105 mph vs. usual ~117 mph). I had no brakes...just two easy turns and ~1300' later. I pumped them a few times with no luck and turned the car in hard in an attempt to put it sideways, which worked. I slid across the right side rumble strip, through the grass, across the track and off the other side, keeping the car sideways. No damage, just lots of dirt and dust. It can happen quickly, and it usually happens when off the brakes then on them again.
S.
Melting Slicks
Joined: Nov 2000
Posts: 2,333
Likes: 32
From: USA
At the 5:40 mark in the video Robert says the pedal was like pushing on concrete.
It's been several years since I did any similar events but I have seen or experienced about every type of brake problem at a track event.
I don't think a firm pedal is a sign of boiled brake fluid. More like new brake pads that are outgassing, also called green fade.
Bedding-in new pads usually takes care of the problem.
I'm betting it was not driver error.
It's been several years since I did any similar events but I have seen or experienced about every type of brake problem at a track event.
I don't think a firm pedal is a sign of boiled brake fluid. More like new brake pads that are outgassing, also called green fade.
Bedding-in new pads usually takes care of the problem.
I'm betting it was not driver error.