ice mode and autocrossing ?'s
10-13-2006, 08:14 AM
#1
Drifting
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ice mode and autocrossing ?'s
I tried the search but not much in the way of answers.
I have an '04 Z06 and I seem to get the non-braking feeling 'ice mode' alot.
Mostly noticed it after changing my driving style but at the same time I did switch to Hawk HP+ pads.
For instance this past weekend there were 2 spots that every run I thought
I was never gonna slow down and one of the spots really required it... long straight into a 36' spaced 3 cone slalom just before the exit.
Do the more agressive pads cause this to happen more? Or is it something I just notice more because I now hard brake before every sharp turn?
Is there something else I need to add/modify to my braking procedure to reduce the occurrence?
I have an '04 Z06 and I seem to get the non-braking feeling 'ice mode' alot.
Mostly noticed it after changing my driving style but at the same time I did switch to Hawk HP+ pads.
For instance this past weekend there were 2 spots that every run I thought
I was never gonna slow down and one of the spots really required it... long straight into a 36' spaced 3 cone slalom just before the exit.Do the more agressive pads cause this to happen more? Or is it something I just notice more because I now hard brake before every sharp turn?
Is there something else I need to add/modify to my braking procedure to reduce the occurrence?
10-13-2006, 08:27 AM
#2
Le Mans Master
I've never experienced it (not that I remember), but I've learned that hammering the brakes can lead to the ABS engaging, probably only on one wheel, but it makes stopping a much harder press on the pedal.
Now I've started braking 1 second earlier, starting lighter and progressively getting harder into the ABS, and my brake effort is lower, and my times have been getting more competitive. (just need better tires, more power, some shocks, suspension bits,....)
HTH, and have a good one,
Mike
Now I've started braking 1 second earlier, starting lighter and progressively getting harder into the ABS, and my brake effort is lower, and my times have been getting more competitive. (just need better tires, more power, some shocks, suspension bits,....)
HTH, and have a good one,
Mike
10-13-2006, 08:44 AM
#3
Melting Slicks
On a tight course you might be on the brakes to long and are running out of boost. With more agressive break pads you can go a little deaper into the corner but you focus on not dragging the brakes, especially if you left foot brake. Also, HP+ pads have a good initial bite while stock pads are more linear, you might be too used of the linear brake pads and should either adjust your driving style or change pads.
10-13-2006, 09:30 AM
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Originally Posted by xilr8n
I tried the search but not much in the way of answers.
I have an '04 Z06 and I seem to get the non-braking feeling 'ice mode' alot.
Mostly noticed it after changing my driving style but at the same time I did switch to Hawk HP+ pads.
For instance this past weekend there were 2 spots that every run I thought I was never gonna slow down and one of the spots really required it... long straight into a 36' spaced 3 cone slalom just before the exit.
Do the more agressive pads cause this to happen more? Or is it something I just notice more because I now hard brake before every sharp turn?
Is there something else I need to add/modify to my braking procedure to reduce the occurrence?
I have an '04 Z06 and I seem to get the non-braking feeling 'ice mode' alot.
Mostly noticed it after changing my driving style but at the same time I did switch to Hawk HP+ pads.
For instance this past weekend there were 2 spots that every run I thought
I was never gonna slow down and one of the spots really required it... long straight into a 36' spaced 3 cone slalom just before the exit.Do the more agressive pads cause this to happen more? Or is it something I just notice more because I now hard brake before every sharp turn?
Is there something else I need to add/modify to my braking procedure to reduce the occurrence?
Not sure how to avoid it but I do know a local SCCA father and son that have experienced ice mode. It was explained as light ABS usage but with each wheel showing a different speed to the EBCM and it just relieve a percentage of brake fluid press thinking the driver has spun the car. Kudos to your smooth driving!
Norm
10-13-2006, 09:56 AM
#5
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I got it once this past summer and took out all the cones in a chicago box. I know why it is called ice mode, feels just like it! I think I induced it by slamming the brakes before letting the car transition some weight to the front. If the brakes go full force before the weight is transferred to the front wheels, the tires have no chance to maintain grip. Worn tires, aggressive pads, slamming the brakes can all add to phenomenon. And as mentioned above , I was beginning to make a turn that also added to the differentiation of the gripping force between the two front tires and confused the puter. In my case, I need to be consistent with 'squeezing' the brake pedal instead of slamming. YMMV...
10-13-2006, 10:53 AM
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Hi Gary!
A couple of thoughts. Are you really experiencing "ice mode" or something else. Is it ABS, which you'll activate earlier with the HP+'s and 710s because they work sooo much better than the stock pads, or do you need to bleed your brake fluid a little because you've overheated it a little over the year and are experiencing brake fade?
Haven driven your car and seeing how it needed the better pads back in the summer, I suspect you're getting into the ABS much quicker than before and need to learn better brake modulation with the grippier pads. Remember that once ABS kicks in you only have about 80% of the braking capacity. Learning to get near 100%, without going over and activating the ABS, is a skill you'll need to learn to go faster.
I've been told that true "ice mode" usually kicks in when the car is going sideways and you stomp on the brakes. The computer assumes, since you are travelling sideways and are applying the brakes that you must be on ice and shuts the brakes off so the wheels can spin and you can regain steering control. With the brakes locked on ice you have no chance to regain steering.
I've had "ice mode" kick in in two types of autox activities. A spin with me going two feet in and ending up going backwards, and a tank slapper where I gave up early and went two feet in. In both cases the brakes totally disappeared and I had to pump the brake to get the computer system to reactivate and apply the brakes. It's definately not ABS or brake fade (which is diagnosed by the pedal going all the way to the floor with out brakes).
True "ice mode" is a scary experience because you are travelling at high speed, usually somewhat out of control, and have no brakes at all. Recognizing it is crucial to survival and accident avoidence and you must pump the brakes to get the computer to reactivate. Also down shifting and letting the clutch out to slow the car can be useful too.
Good luck.
A couple of thoughts. Are you really experiencing "ice mode" or something else. Is it ABS, which you'll activate earlier with the HP+'s and 710s because they work sooo much better than the stock pads, or do you need to bleed your brake fluid a little because you've overheated it a little over the year and are experiencing brake fade?
Haven driven your car and seeing how it needed the better pads back in the summer, I suspect you're getting into the ABS much quicker than before and need to learn better brake modulation with the grippier pads. Remember that once ABS kicks in you only have about 80% of the braking capacity. Learning to get near 100%, without going over and activating the ABS, is a skill you'll need to learn to go faster.
I've been told that true "ice mode" usually kicks in when the car is going sideways and you stomp on the brakes. The computer assumes, since you are travelling sideways and are applying the brakes that you must be on ice and shuts the brakes off so the wheels can spin and you can regain steering control. With the brakes locked on ice you have no chance to regain steering.
I've had "ice mode" kick in in two types of autox activities. A spin with me going two feet in and ending up going backwards, and a tank slapper where I gave up early and went two feet in. In both cases the brakes totally disappeared and I had to pump the brake to get the computer system to reactivate and apply the brakes. It's definately not ABS or brake fade (which is diagnosed by the pedal going all the way to the floor with out brakes).
True "ice mode" is a scary experience because you are travelling at high speed, usually somewhat out of control, and have no brakes at all. Recognizing it is crucial to survival and accident avoidence and you must pump the brakes to get the computer to reactivate. Also down shifting and letting the clutch out to slow the car can be useful too.
Good luck.
10-13-2006, 09:05 PM
#7
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The commonly called "ice mode" does not necessarily have anything to with ice. There are two situations I have experienced that cause a "hard" brake pedal. The pedal does not go to the floor, but feels like you are standing on a brick while you have no brakes whatsoever. This is different from an ABS stop.
The most common is "confusion of the reference" in the ABS system. The reference is what the ABS system believes is the true speed of the vehicle relative to the ground. It really never knows this. It makes assumptions from the 4 wheel speeds, but those vary even during normal driving when you turn. In autocross the common way to trigger it is to have a hard acceleration segment where the rear wheels are spinning and then immediately stand on the brakes. It is worse for left-foot brakers because it happens faster. What happens is that all of a sudden the ABS system sees the brakes applied while the front wheels are going much slower than the rear wheels. Guess what, front wheels must be locking up, so it decides to isolate the pedal while the car blows through a wall of cones with no brakes. ABS is too stupid to know that the rear tires were just spinning and the front tires are at the real vehicle speed.
The second seems to pertain to the vehicle stability control which seems to continue to function even when the traction control is turned off. The EBCM has a lateral accelerometer and yaw rate sensor which gives it some sense of direction/spin. I have had it happen to me where I started to get into a throttle oversteer situation, and upon applying the brakes to try to slow/settle the car, the ABS system decided it knew better and gave me zero brakes (hard pedal). Actually first it gave me just one front brake which helped the car pivot around and spin. Very bad situation. Vehicle spinning helplessly out of control with no brakes.
With some mental training you can learn to drive around the first scenario, but it takes some effort. The second is more difficult since it quickly turns into a panic situation especially if there are solid obstacles near you.
Making any changes to the brake system, rotating masses, etc. starts to confuse the ABS system. It makes TONS of assumptions because it has no idea what surface you are actually on. Is it pavement, dirt, ice, what? It lacks the proper sensors to detect what it needs to know so the calibration is based on accel/decel rates and other factors which are calibrated for the exact brake components that come on the car. Sure it can tolerate some changes, but the more changes you make the harder time it has to figure out what is really happening. OEM's are too cheap to put proper sensors on it, and they probably do not have autocross on the list of calibration scenarios to test. Different cars, and even different model years of Corvettes may behave differently as the calibrations and control strategies evolve.
What amazes me is that for how often I have experienced this hard pedal situation in autocross, it does not happen to people the street (or maybe it does and they don't know it). I can just see the lawyers lined up drooling, if only they knew that the accident could have been caused by the ABS system... Makes me want to accelerate in traffic with wheel spin, stand on the brakes and slam into the guy in front of me. Nobody will ever believe it. Of course I could instrument the car and prove it... maybe then they'll do something about it and fix this big pain in the rear for us.
The most common is "confusion of the reference" in the ABS system. The reference is what the ABS system believes is the true speed of the vehicle relative to the ground. It really never knows this. It makes assumptions from the 4 wheel speeds, but those vary even during normal driving when you turn. In autocross the common way to trigger it is to have a hard acceleration segment where the rear wheels are spinning and then immediately stand on the brakes. It is worse for left-foot brakers because it happens faster. What happens is that all of a sudden the ABS system sees the brakes applied while the front wheels are going much slower than the rear wheels. Guess what, front wheels must be locking up, so it decides to isolate the pedal while the car blows through a wall of cones with no brakes. ABS is too stupid to know that the rear tires were just spinning and the front tires are at the real vehicle speed.
The second seems to pertain to the vehicle stability control which seems to continue to function even when the traction control is turned off. The EBCM has a lateral accelerometer and yaw rate sensor which gives it some sense of direction/spin. I have had it happen to me where I started to get into a throttle oversteer situation, and upon applying the brakes to try to slow/settle the car, the ABS system decided it knew better and gave me zero brakes (hard pedal). Actually first it gave me just one front brake which helped the car pivot around and spin. Very bad situation. Vehicle spinning helplessly out of control with no brakes.
With some mental training you can learn to drive around the first scenario, but it takes some effort. The second is more difficult since it quickly turns into a panic situation especially if there are solid obstacles near you.
Making any changes to the brake system, rotating masses, etc. starts to confuse the ABS system. It makes TONS of assumptions because it has no idea what surface you are actually on. Is it pavement, dirt, ice, what? It lacks the proper sensors to detect what it needs to know so the calibration is based on accel/decel rates and other factors which are calibrated for the exact brake components that come on the car. Sure it can tolerate some changes, but the more changes you make the harder time it has to figure out what is really happening. OEM's are too cheap to put proper sensors on it, and they probably do not have autocross on the list of calibration scenarios to test. Different cars, and even different model years of Corvettes may behave differently as the calibrations and control strategies evolve.
What amazes me is that for how often I have experienced this hard pedal situation in autocross, it does not happen to people the street (or maybe it does and they don't know it). I can just see the lawyers lined up drooling, if only they knew that the accident could have been caused by the ABS system... Makes me want to accelerate in traffic with wheel spin, stand on the brakes and slam into the guy in front of me. Nobody will ever believe it. Of course I could instrument the car and prove it... maybe then they'll do something about it and fix this big pain in the rear for us.
Last edited by ATI Performance; 10-13-2006 at 09:11 PM.
10-13-2006, 09:22 PM
#8
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Bob, good point about the electronics swithed off. I remember reading in the service manual that for the airbags to deploy the C5 has 30 degree yaw off center for the airbags to deploy.
Where you within 30 degrees? Probably most that experienced this situation were.
Good discussion!
Norm
Where you within 30 degrees? Probably most that experienced this situation were.
Good discussion!
Norm
Originally Posted by ATI Performance
The commonly called "ice mode" does not necessarily have anything to with ice. There are two situations I have experienced that cause a "hard" brake pedal. The pedal does not go to the floor, but feels like you are standing on a brick while you have no brakes whatsoever. This is different from an ABS stop.
The most common is "confusion of the reference" in the ABS system. The reference is what the ABS system believes is the true speed of the vehicle relative to the ground. It really never knows this. It makes assumptions from the 4 wheel speeds, but those vary even during normal driving when you turn. In autocross the common way to trigger it is to have a hard acceleration segment where the rear wheels are spinning and then immediately stand on the brakes. It is worse for left-foot brakers because it happens faster. What happens is that all of a sudden the ABS system sees the brakes applied while the front wheels are going much slower than the rear wheels. Guess what, front wheels must be locking up, so it decides to isolate the pedal while the car blows through a wall of cones with no brakes. ABS is too stupid to know that the rear tires were just spinning and the front tires are at the real vehicle speed.
The second seems to pertain to the vehicle stability control which seems to continue to function even when the traction control is turned off. The EBCM has a lateral accelerometer and yaw rate sensor which gives it some sense of direction/spin. I have had it happen to me where I started to get into a throttle oversteer situation, and upon applying the brakes to try to slow/settle the car, the ABS system decided it knew better and gave me zero brakes (hard pedal). Actually first it gave me just one front brake which helped the car pivot around and spin. Very bad situation. Vehicle spinning helplessly out of control with no brakes.
With some mental training you can learn to drive around the first scenario, but it takes some effort. The second is more difficult since it quickly turns into a panic situation especially if there are solid obstacles near you.
Making any changes to the brake system, rotating masses, etc. starts to confuse the ABS system. It makes TONS of assumptions because it has no idea what surface you are actually on. Is it pavement, dirt, ice, what? It lacks the proper sensors to detect what it needs to know so the calibration is based on accel/decel rates and other factors which are calibrated for the exact brake components that come on the car. Sure it can tolerate some changes, but the more changes you make the harder time it has to figure out what is really happening. OEM's are too cheap to put proper sensors on it, and they probably do not have autocross on the list of calibration scenarios to test. Different cars, and even different model years of Corvettes may behave differently as the calibrations and control strategies evolve.
What amazes me is that for how often I have experienced this hard pedal situation in autocross, it does not happen to people the street (or maybe it does and they don't know it). I can just see the lawyers lined up drooling, if only they knew that the accident could have been caused by the ABS system... Makes me want to accelerate in traffic with wheel spin, stand on the brakes and slam into the guy in front of me. Nobody will ever believe it. Of course I could instrument the car and prove it... maybe then they'll do something about it and fix this big pain in the rear for us.
The most common is "confusion of the reference" in the ABS system. The reference is what the ABS system believes is the true speed of the vehicle relative to the ground. It really never knows this. It makes assumptions from the 4 wheel speeds, but those vary even during normal driving when you turn. In autocross the common way to trigger it is to have a hard acceleration segment where the rear wheels are spinning and then immediately stand on the brakes. It is worse for left-foot brakers because it happens faster. What happens is that all of a sudden the ABS system sees the brakes applied while the front wheels are going much slower than the rear wheels. Guess what, front wheels must be locking up, so it decides to isolate the pedal while the car blows through a wall of cones with no brakes. ABS is too stupid to know that the rear tires were just spinning and the front tires are at the real vehicle speed.
The second seems to pertain to the vehicle stability control which seems to continue to function even when the traction control is turned off. The EBCM has a lateral accelerometer and yaw rate sensor which gives it some sense of direction/spin. I have had it happen to me where I started to get into a throttle oversteer situation, and upon applying the brakes to try to slow/settle the car, the ABS system decided it knew better and gave me zero brakes (hard pedal). Actually first it gave me just one front brake which helped the car pivot around and spin. Very bad situation. Vehicle spinning helplessly out of control with no brakes.
With some mental training you can learn to drive around the first scenario, but it takes some effort. The second is more difficult since it quickly turns into a panic situation especially if there are solid obstacles near you.
Making any changes to the brake system, rotating masses, etc. starts to confuse the ABS system. It makes TONS of assumptions because it has no idea what surface you are actually on. Is it pavement, dirt, ice, what? It lacks the proper sensors to detect what it needs to know so the calibration is based on accel/decel rates and other factors which are calibrated for the exact brake components that come on the car. Sure it can tolerate some changes, but the more changes you make the harder time it has to figure out what is really happening. OEM's are too cheap to put proper sensors on it, and they probably do not have autocross on the list of calibration scenarios to test. Different cars, and even different model years of Corvettes may behave differently as the calibrations and control strategies evolve.
What amazes me is that for how often I have experienced this hard pedal situation in autocross, it does not happen to people the street (or maybe it does and they don't know it). I can just see the lawyers lined up drooling, if only they knew that the accident could have been caused by the ABS system... Makes me want to accelerate in traffic with wheel spin, stand on the brakes and slam into the guy in front of me. Nobody will ever believe it. Of course I could instrument the car and prove it... maybe then they'll do something about it and fix this big pain in the rear for us.
10-13-2006, 11:37 PM
#9
Drifting
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Originally Posted by ATI Performance
The most common is "confusion of the reference" in the ABS system. The reference is what the ABS system believes is the true speed of the vehicle relative to the ground. It really never knows this. It makes assumptions from the 4 wheel speeds, but those vary even during normal driving when you turn. In autocross the common way to trigger it is to have a hard acceleration segment where the rear wheels are spinning and then immediately stand on the brakes. It is worse for left-foot brakers because it happens faster. What happens is that all of a sudden the ABS system sees the brakes applied while the front wheels are going much slower than the rear wheels. Guess what, front wheels must be locking up, so it decides to isolate the pedal while the car blows through a wall of cones with no brakes. ABS is too stupid to know that the rear tires were just spinning and the front tires are at the real vehicle speed.
I've had ABS activation before and it never really seemed like this. To me this acts like tons of brake and then all of a sudden 40% braking.
Brakes have been bled. I've never taken (had) the time to look down and see if it says ABS Active on the DIC though.
