Ice Mode
10-26-2017, 08:28 PM
#21
Burning Brakes
I don't get all these posts. I have raced two different C5 since 2004. One of them I have well over 40,000 miles on track racing, not on the street, not commuting the the track, etc. It has 40,000 miles of race practice, qualifying and racing. I have run 315 square setups mostly on Hoosier A tires and in the more recent years 335s on the rear and 315 on the front. Once in a while Kumho V710s, R888s, NT01 and recently Pirelli DH slicks for TA3.
Never once have I had ice mode. I have had ABS fail a few times and that prompted me to install an ABS cutoff switch on my control panel as it is better to manually turn it off when it acts up than to have it acting erratically. When it fails it always turns out to be a wiring or connection issue.
In closing, on the 2002 and later C5 platforms I can say I have never had ice mode and to my knowledge my racing buddies on the same platform have never complained about ice mode, not while I have been within ear shot. Only one guy around 2010 claimed he got ice mode when he completely blew a brake zone and severely hit another car in the process. But I was right next to him when he threw caution to the wind and tried to overtake me in the brake zone. It was poor judgement coupled with complete failure of execution. He called ice mode to dampen criticism, but I know that was not the case.
If you have getting ice mode I proffer you either have a tire size mismatch issue or you are running a C6. It is my understanding that the C6 ABS electronics can and need to be reflashed because that platform has the pre-disposition. Phoenix Performance can do that reflash from what I am told.
Never once have I had ice mode. I have had ABS fail a few times and that prompted me to install an ABS cutoff switch on my control panel as it is better to manually turn it off when it acts up than to have it acting erratically. When it fails it always turns out to be a wiring or connection issue.
In closing, on the 2002 and later C5 platforms I can say I have never had ice mode and to my knowledge my racing buddies on the same platform have never complained about ice mode, not while I have been within ear shot. Only one guy around 2010 claimed he got ice mode when he completely blew a brake zone and severely hit another car in the process. But I was right next to him when he threw caution to the wind and tried to overtake me in the brake zone. It was poor judgement coupled with complete failure of execution. He called ice mode to dampen criticism, but I know that was not the case.
If you have getting ice mode I proffer you either have a tire size mismatch issue or you are running a C6. It is my understanding that the C6 ABS electronics can and need to be reflashed because that platform has the pre-disposition. Phoenix Performance can do that reflash from what I am told.
Botom line.....ABS can be a tool or a crutch depending on how the driver uses or abuses it.
10-27-2017, 09:08 AM
#22
Le Mans Master
"Ice Mode" is a thing, even though it's obviously not an actual planned "mode" per GM's design. It's obviously a function of the calibrations GM programs into the stock ABS system, reacting to certain combinations of input from driver and wheel speed sensors (and maybe the accelerometer?). It's not just Corvettes, either: Camaros at least in 5th-gen version are also notorious for this. Too many autocrossers encounter it for it not to be real, including national championship contenders that I know. And it doesn't seem to afflict cars from other manufacturers nearly as much, so it seems peculiar to GM's ABS calibration strategy. It may not occur on road courses, though, since braking inputs tend to be less impulsive and more planned/gradual. It seems to be worst during autocrosses.
I would never advocate disabling ABS, though. Even on C4s, the system is too helpful to go without, and disabling leaves one with a ton of front brake bias. Earlier advice was to make sure brake inputs are as smooth as possible, and I agree with that. I'd add that less aggressive pads can help with that.
I would never advocate disabling ABS, though. Even on C4s, the system is too helpful to go without, and disabling leaves one with a ton of front brake bias. Earlier advice was to make sure brake inputs are as smooth as possible, and I agree with that. I'd add that less aggressive pads can help with that.
10-27-2017, 03:58 PM
#23
Burning Brakes
C6 Ice Mode Data Logs
Here is what a C6 does in Ice Mode as recorded by an Aim Solo DL. It starts when three or four wheels lock up simultaneously. All the brake bias goes to the rear and you get a hard pedal.
10-27-2017, 08:24 PM
#24
I think the fact that more auto-x guys complain about this is telling. I agree with Oli and race with Oli. However, it happened to me once on the bumps of BRP and it cost me a new set of A6 hoo hoo's that flatspotted. IN is a known issue. All ABS systems have it to some degree. Google porsche caymen gt4...even thier trackcar is having issues. The work arounds have been posted above. Once I experienced IM I know how to avoid it. No problem at all and I can brake deeper now that I could years ago when I experienced IM. Using ABS is just part of racing like learning to heel/toe.
I'm running a T2 C5Z square
I'm running a T2 C5Z square
10-28-2017, 09:20 AM
#25
Burning Brakes
The Bosch Racing ABS system will cost you around $9800 but, it is programmable. The C4s are notorious for "Ice Mode". In order to effectively brake a C4 you either have to make sure that the car is flat and/or not spike the brake system, otherwise you just **** off the ABS system.
10-28-2017, 10:21 PM
#26
Melting Slicks
The term "ice mode" came from the guys at the GM Proving Ground. That's what they called it when we started encountering it in the late 80's when we were running the C4's with the then new aggressive Goodrich tires. We were finding that we could get a "dead" pedal, braking pressure and of course force was limited until you got off the brakes and "recycled" the system.
Investigations by some of the guys at the proving ground found that the abs system was programmed that if the rate of deceleration was very high that the system assumed that the coefficient of friction was low as could only be found on ice or on wet grass and the system assumed that since you weren't on a surface that had much friction, that brake pressure should be limited to that lower value. While the program doesn't call it "ice mode", that's what the guys at the proving ground called it. The name has stuck.
I've never encountered it on my C5, but it was very common on C4's, not as bad on the early 3 channel cars, but if you got only one wheel of the 4 channel cars on the marbles or gravel you'd get into it. As is obvious, if you brake hard with a wheel in the air it's going to stop so fast that it invokes that programming loop and bad things can happen. Also, if you have one wheel in dirt or on a surface with a bunch of marbles on it, then it was very common to get into ice mode.
Smoother braking helps, late and hard is fine, but stabbing isn't. I've found that it was very predictable in that if I would get ice mode it happened in the same place and time on each lap, and if after it happened enough, you caught on pretty quick and learned to recycle the brakes really fast and you didn't get off the track, but you did lose some time.
Only once did we find that we had to do something about it, in 1989 in Cincinnati at a Pro Solo, there was a hump in the track and if you were braking on it you'd get ice mode and end up going into a curb. On that particular day every Corvette had a blow ABS fuse... The Company line was that this particular track "overworked" the ABS and blew the fuses.. Funny how you could overheat a fuse by taking it out of a car and jumping it across a battery.....
Not long after that the SCCA came up with a rule change that all systems on the car had to be "operative" and you couldn't disable things like the ABS...
As I said I haven't found it to be as bad on C5's, but it is a line of code that really shouldn't be there in a serious track car since the reality is that after the wheel starts spinning again full braking should be permitted.
Investigations by some of the guys at the proving ground found that the abs system was programmed that if the rate of deceleration was very high that the system assumed that the coefficient of friction was low as could only be found on ice or on wet grass and the system assumed that since you weren't on a surface that had much friction, that brake pressure should be limited to that lower value. While the program doesn't call it "ice mode", that's what the guys at the proving ground called it. The name has stuck.
I've never encountered it on my C5, but it was very common on C4's, not as bad on the early 3 channel cars, but if you got only one wheel of the 4 channel cars on the marbles or gravel you'd get into it. As is obvious, if you brake hard with a wheel in the air it's going to stop so fast that it invokes that programming loop and bad things can happen. Also, if you have one wheel in dirt or on a surface with a bunch of marbles on it, then it was very common to get into ice mode.
Smoother braking helps, late and hard is fine, but stabbing isn't. I've found that it was very predictable in that if I would get ice mode it happened in the same place and time on each lap, and if after it happened enough, you caught on pretty quick and learned to recycle the brakes really fast and you didn't get off the track, but you did lose some time.
Only once did we find that we had to do something about it, in 1989 in Cincinnati at a Pro Solo, there was a hump in the track and if you were braking on it you'd get ice mode and end up going into a curb. On that particular day every Corvette had a blow ABS fuse... The Company line was that this particular track "overworked" the ABS and blew the fuses.. Funny how you could overheat a fuse by taking it out of a car and jumping it across a battery.....
Not long after that the SCCA came up with a rule change that all systems on the car had to be "operative" and you couldn't disable things like the ABS...
As I said I haven't found it to be as bad on C5's, but it is a line of code that really shouldn't be there in a serious track car since the reality is that after the wheel starts spinning again full braking should be permitted.
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Kelly.s (10-29-2017)
10-29-2017, 02:42 PM
#27
The term "ice mode" came from the guys at the GM Proving Ground. That's what they called it when we started encountering it in the late 80's when we were running the C4's with the then new aggressive Goodrich tires. We were finding that we could get a "dead" pedal, braking pressure and of course force was limited until you got off the brakes and "recycled" the system.
Investigations by some of the guys at the proving ground found that the abs system was programmed that if the rate of deceleration was very high that the system assumed that the coefficient of friction was low as could only be found on ice or on wet grass and the system assumed that since you weren't on a surface that had much friction, that brake pressure should be limited to that lower value. While the program doesn't call it "ice mode", that's what the guys at the proving ground called it. The name has stuck.
I've never encountered it on my C5, but it was very common on C4's, not as bad on the early 3 channel cars, but if you got only one wheel of the 4 channel cars on the marbles or gravel you'd get into it. As is obvious, if you brake hard with a wheel in the air it's going to stop so fast that it invokes that programming loop and bad things can happen. Also, if you have one wheel in dirt or on a surface with a bunch of marbles on it, then it was very common to get into ice mode.
Smoother braking helps, late and hard is fine, but stabbing isn't. I've found that it was very predictable in that if I would get ice mode it happened in the same place and time on each lap, and if after it happened enough, you caught on pretty quick and learned to recycle the brakes really fast and you didn't get off the track, but you did lose some time.
Only once did we find that we had to do something about it, in 1989 in Cincinnati at a Pro Solo, there was a hump in the track and if you were braking on it you'd get ice mode and end up going into a curb. On that particular day every Corvette had a blow ABS fuse... The Company line was that this particular track "overworked" the ABS and blew the fuses.. Funny how you could overheat a fuse by taking it out of a car and jumping it across a battery.....
Not long after that the SCCA came up with a rule change that all systems on the car had to be "operative" and you couldn't disable things like the ABS...
As I said I haven't found it to be as bad on C5's, but it is a line of code that really shouldn't be there in a serious track car since the reality is that after the wheel starts spinning again full braking should be permitted.
Investigations by some of the guys at the proving ground found that the abs system was programmed that if the rate of deceleration was very high that the system assumed that the coefficient of friction was low as could only be found on ice or on wet grass and the system assumed that since you weren't on a surface that had much friction, that brake pressure should be limited to that lower value. While the program doesn't call it "ice mode", that's what the guys at the proving ground called it. The name has stuck.
I've never encountered it on my C5, but it was very common on C4's, not as bad on the early 3 channel cars, but if you got only one wheel of the 4 channel cars on the marbles or gravel you'd get into it. As is obvious, if you brake hard with a wheel in the air it's going to stop so fast that it invokes that programming loop and bad things can happen. Also, if you have one wheel in dirt or on a surface with a bunch of marbles on it, then it was very common to get into ice mode.
Smoother braking helps, late and hard is fine, but stabbing isn't. I've found that it was very predictable in that if I would get ice mode it happened in the same place and time on each lap, and if after it happened enough, you caught on pretty quick and learned to recycle the brakes really fast and you didn't get off the track, but you did lose some time.
Only once did we find that we had to do something about it, in 1989 in Cincinnati at a Pro Solo, there was a hump in the track and if you were braking on it you'd get ice mode and end up going into a curb. On that particular day every Corvette had a blow ABS fuse... The Company line was that this particular track "overworked" the ABS and blew the fuses.. Funny how you could overheat a fuse by taking it out of a car and jumping it across a battery.....
Not long after that the SCCA came up with a rule change that all systems on the car had to be "operative" and you couldn't disable things like the ABS...
As I said I haven't found it to be as bad on C5's, but it is a line of code that really shouldn't be there in a serious track car since the reality is that after the wheel starts spinning again full braking should be permitted.
Thanks for the great explanation. Always something to learn.
Kelly
10-29-2017, 04:34 PM
#28
Melting Slicks
Driving Autocross in a C5Z06 I would experience "ice mode" a few times. To help cure this problem, I would run front brake pads with less initial bite, brake earlier, and have less front compression in the shocks. 
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Tomswheels (10-29-2017)
11-04-2017, 09:58 PM
#29
Wow I learned a ton just now
Can the ABS programming be modified?
I drive many tracks with bumpy sections and have gotten ""Ice mode"" in those spots. mostly in C7Z06's but Im sure my C6 isnt far from it in these spots.
Is there a less costly option for a good ABS than the BMW one?
Can the ABS programming be modified?
I drive many tracks with bumpy sections and have gotten ""Ice mode"" in those spots. mostly in C7Z06's but Im sure my C6 isnt far from it in these spots.
Is there a less costly option for a good ABS than the BMW one?
11-04-2017, 10:04 PM
#30
11-04-2017, 10:35 PM
#31
Burning Brakes
11-17-2017, 11:51 AM
#32
Race Director
Member Since: Oct 2000
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I have only experienced once that I can recall. I suppose I have been lucky in my '03 considering I run R6's/R7's but I do have very stiff front and rear springs so, perhaps, that helps keep everything planted nicely at all four corners.
11-18-2017, 07:22 AM
#33
This is where I ended up as well. After multiple IM occurrences I switched from Ferrodo front brake pads to a G-Loc pad with less initial bite. IM mostly affected me at the Championships in Lincoln due to the seams between the concrete sections. The base C5s run such a narrow front tire... it's easy to overpower it.
11-19-2017, 10:34 AM
#34
Race Director
GM did themselves a disservice if they indeed came up with the term "ice mode". It's a failure, not a mode, simple. In 25 years racing corvettes, I've had it 1 time, in a c6 at VIR, in a very awkward off-line entry on poor, wrinkled asphalt.
All systems have their limits, and if you have a healthy brake system with properly matched friction components (pads, tires and surface), you should rarely if ever reach the limits of the ABS system in a modern Corvette.
If you are seeing this often, you have a mechanical problem or you are doing it wrong.
All systems have their limits, and if you have a healthy brake system with properly matched friction components (pads, tires and surface), you should rarely if ever reach the limits of the ABS system in a modern Corvette.
If you are seeing this often, you have a mechanical problem or you are doing it wrong.
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Olitho (11-19-2017)
11-19-2017, 11:33 AM
#35
Drifting
I don't believe I ever had the issue come up in C6 2008 coupe with R888/NT01s or C5 FRC 1999 racecar. I did remove the ABS system entirely and run SL6 Wilwood (not narrow or wide style) front six pot calipers and stock rear equipment with HH pads and I have zero regrets. I do strongly suggest hooking up a mity vac or similar style system that uses an compressor to suck (not blow) pressure at each caliper. I had probably bled a dozen times and used power pressured systems at the reservoir twice. The mity vac pulled nasty stuff left in the rear calipers that no other system/method worked. So I think you can have air/water/crap stuck in rear calipers that may cause issues. 2 cents.