ICE MOde ! ... off track event :( is there a fix ?
06-08-2011, 01:00 AM
#21
Race Director
Brake pad bite and shock rebound stiffness can have an influence on whether or not you get into ice mode.
Ice mode isn't hard to understand. If a wheel stops faster than a specific rate, the computer invokes ice mode. The rate is based on how fast the wheel will stop if it has weight on it and traction. If there isn't any weight on the wheel, or the traction is really low, the wheel will stop very fast. If any one wheel stops too fast ice mode is invoked. When it is invoked, the brake line pressure is limited to all four wheels to correspond to a deceleration rate of (I think it was but I'm not positive and it really doesn't matter) 0.1 g's. The mode is latched in until the brakes are released then the brakes can be applied again and you have another chance at stopping at a higher rate.
Most of the times that I have gotten into ice mode it has been the front tires that did it in, because of the higher amount of braking done on the front wheels and one or both of those wheels was light or on dirt.
I don't know if changing the bias will help. It might if you are finding that you are getting into it frequently because you are hammering on the brakes and have a real aggressive setup, then a change in rear pads could possibly help.
But most of the time that I've gotten into ice mode it has been the result of the front tires being light or on a patch of sand. If a front wheel is light and you hammer the brakes, you ARE going into ice mode, giving the rear more bias isn't going to do anything to prevent it.
I also don't understand the last statement
Changing the brake bias doesn't effect weight transfer. The amount of weight transferred is based on the height of the CG, the wheelbase and the deceleration rate. It is a common misconception that the bias effects how much weight is transferred, but it simply doesn't. If the thought is that changing the brake bias changes the weight is on the wheels at that end of the car and that will effect getting into ice mode, the answer is, well, no...
Ice mode isn't hard to understand. If a wheel stops faster than a specific rate, the computer invokes ice mode. The rate is based on how fast the wheel will stop if it has weight on it and traction. If there isn't any weight on the wheel, or the traction is really low, the wheel will stop very fast. If any one wheel stops too fast ice mode is invoked. When it is invoked, the brake line pressure is limited to all four wheels to correspond to a deceleration rate of (I think it was but I'm not positive and it really doesn't matter) 0.1 g's. The mode is latched in until the brakes are released then the brakes can be applied again and you have another chance at stopping at a higher rate.
Most of the times that I have gotten into ice mode it has been the front tires that did it in, because of the higher amount of braking done on the front wheels and one or both of those wheels was light or on dirt.
I don't know if changing the bias will help. It might if you are finding that you are getting into it frequently because you are hammering on the brakes and have a real aggressive setup, then a change in rear pads could possibly help.
But most of the time that I've gotten into ice mode it has been the result of the front tires being light or on a patch of sand. If a front wheel is light and you hammer the brakes, you ARE going into ice mode, giving the rear more bias isn't going to do anything to prevent it.
I also don't understand the last statement
Changing the brake bias doesn't effect weight transfer. The amount of weight transferred is based on the height of the CG, the wheelbase and the deceleration rate. It is a common misconception that the bias effects how much weight is transferred, but it simply doesn't. If the thought is that changing the brake bias changes the weight is on the wheels at that end of the car and that will effect getting into ice mode, the answer is, well, no...
Well described, and I think it's a pretty dumb f#$%ing system myself. I can probably come up with a dozen scenarios where the car driven both "regular" and high performance mode could decelerate one or more wheels faster than "some specific rate" and still benefit from full braking power. How about when you get in the marbles or sand on the side of a road? And none of those would be driving on ice.
Who the hell drives a Vette on ice? Yeah, I know someone will post about black ice in TX.
GM designed the system for a one in a million occurance and screwed all the guys that drive the car at 8/9/10 tenths.
ICE MODE SHOULD GO OFF WHEN ALL THE NANNIES ARE TURNED OFF. Would that have been so hard for a brake engineer to figure out?
Last edited by froggy47; 06-08-2011 at 12:06 PM.
06-08-2011, 01:42 AM
#22
Le Mans Master
Thread Starter
Brake pad bite and shock rebound stiffness can have an influence on whether or not you get into ice mode.
Ice mode isn't hard to understand. If a wheel stops faster than a specific rate, the computer invokes ice mode. The rate is based on how fast the wheel will stop if it has weight on it and traction. If there isn't any weight on the wheel, or the traction is really low, the wheel will stop very fast. If any one wheel stops too fast ice mode is invoked. When it is invoked, the brake line pressure is limited to all four wheels to correspond to a deceleration rate of (I think it was but I'm not positive and it really doesn't matter) 0.1 g's. The mode is latched in until the brakes are released then the brakes can be applied again and you have another chance at stopping at a higher rate.
Most of the times that I have gotten into ice mode it has been the front tires that did it in, because of the higher amount of braking done on the front wheels and one or both of those wheels was light or on dirt.
I don't know if changing the bias will help. It might if you are finding that you are getting into it frequently because you are hammering on the brakes and have a real aggressive setup, then a change in rear pads could possibly help.
But most of the time that I've gotten into ice mode it has been the result of the front tires being light or on a patch of sand. If a front wheel is light and you hammer the brakes, you ARE going into ice mode, giving the rear more bias isn't going to do anything to prevent it.
I also don't understand the last statement
Changing the brake bias doesn't effect weight transfer. The amount of weight transferred is based on the height of the CG, the wheelbase and the deceleration rate. It is a common misconception that the bias effects how much weight is transferred, but it simply doesn't. If the thought is that changing the brake bias changes the weight is on the wheels at that end of the car and that will effect getting into ice mode, the answer is, well, no...
Ice mode isn't hard to understand. If a wheel stops faster than a specific rate, the computer invokes ice mode. The rate is based on how fast the wheel will stop if it has weight on it and traction. If there isn't any weight on the wheel, or the traction is really low, the wheel will stop very fast. If any one wheel stops too fast ice mode is invoked. When it is invoked, the brake line pressure is limited to all four wheels to correspond to a deceleration rate of (I think it was but I'm not positive and it really doesn't matter) 0.1 g's. The mode is latched in until the brakes are released then the brakes can be applied again and you have another chance at stopping at a higher rate.
Most of the times that I have gotten into ice mode it has been the front tires that did it in, because of the higher amount of braking done on the front wheels and one or both of those wheels was light or on dirt.
I don't know if changing the bias will help. It might if you are finding that you are getting into it frequently because you are hammering on the brakes and have a real aggressive setup, then a change in rear pads could possibly help.
But most of the time that I've gotten into ice mode it has been the result of the front tires being light or on a patch of sand. If a front wheel is light and you hammer the brakes, you ARE going into ice mode, giving the rear more bias isn't going to do anything to prevent it.
I also don't understand the last statement
Changing the brake bias doesn't effect weight transfer. The amount of weight transferred is based on the height of the CG, the wheelbase and the deceleration rate. It is a common misconception that the bias effects how much weight is transferred, but it simply doesn't. If the thought is that changing the brake bias changes the weight is on the wheels at that end of the car and that will effect getting into ice mode, the answer is, well, no...
only thing i can think of is this might get the rear wheels to stop spinning before the front ones? but it seems running the same friction rated pad on all four calipers does seem to help. 
ONE TIME i ran HT10's on the front and HP plus on the rears and had a really bad booboo with ice mode a few years back. I had no idea what it was back then, Boy Howdy....I know now!
06-08-2011, 01:44 AM
#23
Le Mans Master
Thread Starter
Well described, and I think it's a pretty dumb f#$%ing system myself. I can probably come up with a dozen scenarios where the car driven both "regular" and high performance mode could decelerate one or more wheels faster than "some specific rate" and still benefit from full braking power. How about when you get in the marbles or sand on the side of a road? And none of those would be driving on ice.
Who the hell drives a Vette on ice? Yeah, I know someone will post about black ice in TX.
GM designed the system for a one in a million occurance and screwed all the guys that drive the car at 8/9/10 tenths.
Who the hell drives a Vette on ice? Yeah, I know someone will post about black ice in TX.
GM designed the system for a one in a million occurance and screwed all the guys that drive the car at 8/9/10 tenths.
06-08-2011, 01:45 AM
#24
Le Mans Master
Thread Starter
06-08-2011, 02:00 AM
#25
Drifting
06-08-2011, 02:27 AM
#26
Le Mans Master
Thread Starter
06-08-2011, 10:48 PM
#27
rustyguns, are you suggesting the flat spots and longer stopping distances are bias involved or otherwise? Reason I ask is because not a single race car I have driven, as well as my shifter kart, has had abs. Furthermore, most have had dual master cylinders and manual brakes. I am confident I can stop better with a properly setup brake system minus abs vs. a factory abs system. If we were talking about an ultra high end, race only system, motec, etc., then I would probably agree. I simply prefer to do my own modulation rather than just jam on the brakes and let the computers do the rest.
06-09-2011, 12:19 AM
#28
Le Mans Master
rustyguns, are you suggesting the flat spots and longer stopping distances are bias involved or otherwise? Reason I ask is because not a single race car I have driven, as well as my shifter kart, has had abs. Furthermore, most have had dual master cylinders and manual brakes. I am confident I can stop better with a properly setup brake system minus abs vs. a factory abs system. If we were talking about an ultra high end, race only system, motec, etc., then I would probably agree. I simply prefer to do my own modulation rather than just jam on the brakes and let the computers do the rest.
Oli
06-09-2011, 02:00 AM
#29
No put down of the OP or any others who have experienced Icemode but since few of us have telemetry for things like brake application pressure vs. time it is hard to know what really happened in the heat of battle. Most of us have upset the oem design too running on race rubber and race pads. Add system changes and aberant driver inputs and tarmac conditions and ice mode is not so way out there. I really don't think icemode is any different than one's last mistake that caused one to spin off the track. If we had brake telemetry I would not be surprised at all if most of the ice mode were caused by us compounded by other factors like pads etc.. and not a GM gremlin deciding right now to bite you in the a$$. I mean that respectfully by the way.
06-09-2011, 02:23 AM
#31
Le Mans Master
Thread Starter
rustyguns, are you suggesting the flat spots and longer stopping distances are bias involved or otherwise? Reason I ask is because not a single race car I have driven, as well as my shifter kart, has had abs. Furthermore, most have had dual master cylinders and manual brakes. I am confident I can stop better with a properly setup brake system minus abs vs. a factory abs system. If we were talking about an ultra high end, race only system, motec, etc., then I would probably agree. I simply prefer to do my own modulation rather than just jam on the brakes and let the computers do the rest.
because i can stop faster than 95% of the other non abs cars on the track 
its the only way i can catch those 500 hp non abs guys 
06-09-2011, 02:24 AM
#32
Le Mans Master
Thread Starter
No put down of the OP or any others who have experienced Icemode but since few of us have telemetry for things like brake application pressure vs. time it is hard to know what really happened in the heat of battle. Most of us have upset the oem design too running on race rubber and race pads. Add system changes and aberant driver inputs and tarmac conditions and ice mode is not so way out there. I really don't think icemode is any different than one's last mistake that caused one to spin off the track. If we had brake telemetry I would not be surprised at all if most of the ice mode were caused by us compounded by other factors like pads etc.. and not a GM gremlin deciding right now to bite you in the a$$. I mean that respectfully by the way.
06-09-2011, 07:10 AM
#33
Team Owner
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I don't think with a Corvette Z06 brake system that you can out-brake the ABS on that car, especially in tricky brake zones involving uneven surfaces and declining radiuses, etc. I have come to this conclusion racing on some tracks I know really really well, with ABS functioning, ABS malfunctioning and the ABS fuse pulled. The best and most effective overall braking is with the ABS in my opinion. COrvette ABS, while not a Borg Warner system is running at 10x the sampling rate of regular passenger car ABS systems. It seems pretty effective to me.
Oli
Oli
06-10-2011, 12:22 AM
#34
My car is a '99 FRC. The brakes are not bad I just think the abs is a little intrusive and I hate the fact that ice mode is possible. Like I mentioned above, I nearly lost my street car because of it yet of the dozens of actual races in true race cars, much more intense environment, I have never had such an issue. However, my street car is not so inspiring in some situations on the track. Brakes or otherwise. Maybe I'm just old school, but I prefer to be in complete control. Anyway, do the later cars have different programing, etc. (if so what) than my '99?
06-10-2011, 12:43 AM
#35
Race Director
My car is a '99 FRC. The brakes are not bad I just think the abs is a little intrusive and I hate the fact that ice mode is possible. Like I mentioned above, I nearly lost my street car because of it yet of the dozens of actual races in true race cars, much more intense environment, I have never had such an issue. However, my street car is not so inspiring in some situations on the track. Brakes or otherwise. Maybe I'm just old school, but I prefer to be in complete control. Anyway, do the later cars have different programing, etc. (if so what) than my '99?
06-10-2011, 09:16 AM
#36
Melting Slicks
Fatbillybob is right, for most of the world the system works just fine, and there isn't much of an issue with it.... But,,,,, the system could be a lot better and it wouldn't take more than a few hours of programming to make it a whole lot smarter.
The system could be greatly improved since for the last 15 years or so we have had a fully functional 4 wheel system (the early C4's combined the rear braking ABS). What they need to do is compare all 4 wheels for and if three of them didn't show high rates of deceleration activate normal ABS. The original ice mode logic came out of the three channel system and our present day systems are a lot smarter.
Another thing they could very easily do is cut out the ice mode algorithm if the car is in performance or competitive mode. You gotta figure that we probably aren't going to encounter ice on the race track.
Lastly, I am surprised that GM hasn't been sued over this feature by now. I suspect that there have been some accidents that were caused by this feature. If there have I'd bet there was a quick settlement and the plantiff signed a gag order so that he couldn't ever talk about it. What may have happened is that the poor sap who got "iced" was saying "I had my foot on the brake and the car wouldn't stop", was just ignored by anybody he complained to. Even in the Corvette community there isn't a lot of knowledge about this feature, even less so in the general public. When I was working for GM my friends at the proving ground and in the Vehicle Dynamics group were fairly blasé about the subject, which did surprise me.
The system could be greatly improved since for the last 15 years or so we have had a fully functional 4 wheel system (the early C4's combined the rear braking ABS). What they need to do is compare all 4 wheels for and if three of them didn't show high rates of deceleration activate normal ABS. The original ice mode logic came out of the three channel system and our present day systems are a lot smarter.
Another thing they could very easily do is cut out the ice mode algorithm if the car is in performance or competitive mode. You gotta figure that we probably aren't going to encounter ice on the race track.
Lastly, I am surprised that GM hasn't been sued over this feature by now. I suspect that there have been some accidents that were caused by this feature. If there have I'd bet there was a quick settlement and the plantiff signed a gag order so that he couldn't ever talk about it. What may have happened is that the poor sap who got "iced" was saying "I had my foot on the brake and the car wouldn't stop", was just ignored by anybody he complained to. Even in the Corvette community there isn't a lot of knowledge about this feature, even less so in the general public. When I was working for GM my friends at the proving ground and in the Vehicle Dynamics group were fairly blasé about the subject, which did surprise me.
06-10-2011, 12:35 PM
#37
Race Director
Fatbillybob is right, for most of the world the system works just fine, and there isn't much of an issue with it.... But,,,,, the system could be a lot better and it wouldn't take more than a few hours of programming to make it a whole lot smarter.
The system could be greatly improved since for the last 15 years or so we have had a fully functional 4 wheel system (the early C4's combined the rear braking ABS). What they need to do is compare all 4 wheels for and if three of them didn't show high rates of deceleration activate normal ABS. The original ice mode logic came out of the three channel system and our present day systems are a lot smarter.
Another thing they could very easily do is cut out the ice mode algorithm if the car is in performance or competitive mode. You gotta figure that we probably aren't going to encounter ice on the race track.
Lastly, I am surprised that GM hasn't been sued over this feature by now. I suspect that there have been some accidents that were caused by this feature. If there have I'd bet there was a quick settlement and the plantiff signed a gag order so that he couldn't ever talk about it. What may have happened is that the poor sap who got "iced" was saying "I had my foot on the brake and the car wouldn't stop", was just ignored by anybody he complained to. Even in the Corvette community there isn't a lot of knowledge about this feature, even less so in the general public. When I was working for GM my friends at the proving ground and in the Vehicle Dynamics group were fairly blasé about the subject, which did surprise me.
The system could be greatly improved since for the last 15 years or so we have had a fully functional 4 wheel system (the early C4's combined the rear braking ABS). What they need to do is compare all 4 wheels for and if three of them didn't show high rates of deceleration activate normal ABS. The original ice mode logic came out of the three channel system and our present day systems are a lot smarter.
Another thing they could very easily do is cut out the ice mode algorithm if the car is in performance or competitive mode. You gotta figure that we probably aren't going to encounter ice on the race track.
Lastly, I am surprised that GM hasn't been sued over this feature by now. I suspect that there have been some accidents that were caused by this feature. If there have I'd bet there was a quick settlement and the plantiff signed a gag order so that he couldn't ever talk about it. What may have happened is that the poor sap who got "iced" was saying "I had my foot on the brake and the car wouldn't stop", was just ignored by anybody he complained to. Even in the Corvette community there isn't a lot of knowledge about this feature, even less so in the general public. When I was working for GM my friends at the proving ground and in the Vehicle Dynamics group were fairly blasé about the subject, which did surprise me.
06-10-2011, 01:28 PM
#38
Melting Slicks
My C4 was very sensitive over a series of bumps, if I was braking into a corner. Pocono North had such a set of bumps, before the final turn.
It was like the pedal was pushing back up at you.
It was like the pedal was pushing back up at you.
06-10-2011, 09:01 PM
#39
Racer
Member Since: Sep 2008
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I had ABS issues. Actually my EBCM just got repaired by ABS fixer and its in the process of getting shipped back.
Anyway, with the pads I was running and no ABS I had too much rear bias and with no ABS (and no dynamic bias) I would lock up the RR tire every single time if I tried to brake more than 50% and the back end would or course start to come around. Not very confidence inspiring.
I'm sure one could mechanically balance buy using a better match front to rear friction level but its nice to have the system dynamically take care of bias.
I never even realized there was an ice mode before this post. Something to look out for when I get a more agressive setup and driving I suppose.
Anyway, with the pads I was running and no ABS I had too much rear bias and with no ABS (and no dynamic bias) I would lock up the RR tire every single time if I tried to brake more than 50% and the back end would or course start to come around. Not very confidence inspiring.
I'm sure one could mechanically balance buy using a better match front to rear friction level but its nice to have the system dynamically take care of bias.
I never even realized there was an ice mode before this post. Something to look out for when I get a more agressive setup and driving I suppose.
10-05-2017, 04:03 PM
#40
Intermediate
I experienced ice mode once at the end of Putnam's straightaway at over 120 mph. I think I stabbed the brakes especially hard, and the pedal pushed back against my foot. For a moment it felt like there was no braking.
I think I instinctively lifted to reduce pedal force and pushed again (like I was pumping) and the brake force came back (thankfully).
After that I consciously avoided "stabbing" the pedal, and I had no further problems.
tq
I think I instinctively lifted to reduce pedal force and pushed again (like I was pumping) and the brake force came back (thankfully).
After that I consciously avoided "stabbing" the pedal, and I had no further problems.
tq