Ice Mode...who has experienced it ?????
11-23-2018, 10:27 PM
#101
Instructor
PoorSha, no pedal position or brake pressure. I only use a traqmate without any of the A/D inputs. The ramp rate of the deceleration on lap 10 was one of the lower slopes. The top deceleration braking G's was right in the middle of the pack. When I'm starting to cross track under braking, the G's are lowest of all but two laps. I think a result of the maximum braking force the ABS decided to allow while in this FUBAR mode. Top speed was middle of the pack as well. This lap of course had the higher top speed deeper into the turn with the lower g's due to the brake controller's pre-determined brake pressure...
11-23-2018, 10:42 PM
#102
Instructor
Great emergency execution. The driving or braking is an issue. I definitely do not agree with the software decision that is made. I think there is a physical deceleration limit and sample time limit that causes the control to make a decision and induce 'ice mode'. The Stoptech brakes (from what I can gather) are good enough brakes for the speeds/accelerations I'm driving. I think the AP setup is better but Stoptech is very good. What I really need is the Bosch Motorsports ABS controller. Without that, I have to start breaking a little earlier, a little less aggressive. Could change pads to 'soften' the initial bite...
11-24-2018, 05:05 PM
#104
Instructor
Dave,
I'd rather not have the surprise of no brakes 'ice mode' as it's referred to. That simple. If it's >50F and the car is going 150MPH provide normal ABS functionality, not the hard pedal 'ice mode'. That would be my ask for a conclusion.
I'd rather not have the surprise of no brakes 'ice mode' as it's referred to. That simple. If it's >50F and the car is going 150MPH provide normal ABS functionality, not the hard pedal 'ice mode'. That would be my ask for a conclusion.
02-19-2019, 09:21 PM
#105
Safety Car
Found this "explanation" or idea for an explanation on another forum:
Hard weight transfer over the front at high speed (due to hard braking) can lift enough weight off the rear wheels that the rotational force of the wheel/tire overcomes the friction of the rear brake pads and they over rotate slightly. It isn’t any kind of an issue for the driver other than the (undefeatable even if full Race PTM or all traction off modes) traction system freaks the hell out over math and thinks the fronts are starting to lock up on ice since they’re rotating slower now “than they should”. Braking power is instantly hugely reduced in an attempt to correct the “traction imbalance” and you sail past your braking zone carrying waaaaay too much speed until you get the nuts to lift off the pedal completely and get back on the brakes again, which is the only way to regain full braking power.
Hard weight transfer over the front at high speed (due to hard braking) can lift enough weight off the rear wheels that the rotational force of the wheel/tire overcomes the friction of the rear brake pads and they over rotate slightly. It isn’t any kind of an issue for the driver other than the (undefeatable even if full Race PTM or all traction off modes) traction system freaks the hell out over math and thinks the fronts are starting to lock up on ice since they’re rotating slower now “than they should”. Braking power is instantly hugely reduced in an attempt to correct the “traction imbalance” and you sail past your braking zone carrying waaaaay too much speed until you get the nuts to lift off the pedal completely and get back on the brakes again, which is the only way to regain full braking power.
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Mikec7z (02-20-2019)
02-20-2019, 02:22 AM
#106
Found this "explanation" or idea for an explanation on another forum:
Hard weight transfer over the front at high speed (due to hard braking) can lift enough weight off the rear wheels that the rotational force of the wheel/tire overcomes the friction of the rear brake pads and they over rotate slightly. It isn’t any kind of an issue for the driver other than the (undefeatable even if full Race PTM or all traction off modes) traction system freaks the hell out over math and thinks the fronts are starting to lock up on ice since they’re rotating slower now “than they should”. Braking power is instantly hugely reduced in an attempt to correct the “traction imbalance” and you sail past your braking zone carrying waaaaay too much speed until you get the nuts to lift off the pedal completely and get back on the brakes again, which is the only way to regain full braking power.
Hard weight transfer over the front at high speed (due to hard braking) can lift enough weight off the rear wheels that the rotational force of the wheel/tire overcomes the friction of the rear brake pads and they over rotate slightly. It isn’t any kind of an issue for the driver other than the (undefeatable even if full Race PTM or all traction off modes) traction system freaks the hell out over math and thinks the fronts are starting to lock up on ice since they’re rotating slower now “than they should”. Braking power is instantly hugely reduced in an attempt to correct the “traction imbalance” and you sail past your braking zone carrying waaaaay too much speed until you get the nuts to lift off the pedal completely and get back on the brakes again, which is the only way to regain full braking power.
A good test would be for someone to beef up the back brakes more than they would normally, and then see if the car still enters into ice mode when a person locks up the brakes.
I still believe it is simply time from brake pressed to time of lockup, and if thats too short of a time, it determines ice mode. However, I would prefer you be correct that it is the front wheels relative to the back wheels, as that is a problem we can then solve.
Last edited by Mikec7z; 02-20-2019 at 02:51 AM.
02-20-2019, 08:33 AM
#107
Advanced
I’ve been autocrossing a few years now and I’ve experienced Ice mode in a few different cars. In my experience it happens more on my first lap when the tires are cold, when I’m asking too much of the tires or it is a bumpy section of the lot.
In my Lotus Elise, it has tiny front tires with a big front sway bar and it is very easy to lock up one of the front tires. A couple things I have done to “fix” the ice mode on my Lotus, I put Orielly’s crappy pads on the front with Hawk HPS pads on the rear and I stopped left foot braking. It still happens but not nearly as much.
With my 2015 Z06 I’ve noticed a delay from the time I let off the gas to the time the electronics in the throttle body actually closes. This is even worse if you do a quick stab on and off the throttle with your foot and the electronics are trying to catch up. The car is still accelerating forward when I’m trying to brake. I still get Ice mode from time to time in my Z06 and it’s something I’ve learned to drive around by getting off the gas earlier, braking earlier, and braking more progressively. I am running 19X10 and 19X12’s with square 305 RE-71s with stock steel rotors and stock pads in SS.
Looking at the OP’s first video, I can see that the brakes were applied before the throttle was fully released. Add that to the electronic delay and the car is still accelerating forward while you are trying to brake. The other drivers in your car seem to have 0 throttle before their brake application which seems like that should work, but they experience Ice mode also. I’m lost when it comes to your car.
In my Lotus Elise, it has tiny front tires with a big front sway bar and it is very easy to lock up one of the front tires. A couple things I have done to “fix” the ice mode on my Lotus, I put Orielly’s crappy pads on the front with Hawk HPS pads on the rear and I stopped left foot braking. It still happens but not nearly as much.
With my 2015 Z06 I’ve noticed a delay from the time I let off the gas to the time the electronics in the throttle body actually closes. This is even worse if you do a quick stab on and off the throttle with your foot and the electronics are trying to catch up. The car is still accelerating forward when I’m trying to brake. I still get Ice mode from time to time in my Z06 and it’s something I’ve learned to drive around by getting off the gas earlier, braking earlier, and braking more progressively. I am running 19X10 and 19X12’s with square 305 RE-71s with stock steel rotors and stock pads in SS.
Looking at the OP’s first video, I can see that the brakes were applied before the throttle was fully released. Add that to the electronic delay and the car is still accelerating forward while you are trying to brake. The other drivers in your car seem to have 0 throttle before their brake application which seems like that should work, but they experience Ice mode also. I’m lost when it comes to your car.
02-20-2019, 09:45 AM
#108
Safety Car
In 98 I had an early delivery Camaro 1LE I was running in SCCA autox and had big problems w wheel hop on hard braking. At Memphis FBod 98 I talked w the then chief engineer for Camaro.. He said they had too much rear brake bias in the car and suggested I take out some rear brake. Knowing my class rules prohibited proportioning valves he suggested I grind down the edges of the rear brake pads to accomplish that. I took the rear pads down from 4-5 square inches to a contact surface about the size of a quarter. Voila! No more wheel hop.
Last edited by pkincy; 02-20-2019 at 09:46 AM.
02-20-2019, 02:11 PM
#109
Safety Car
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This is great information because it may mean that upgrading the front brakes, and not the back brakes/pads, is what causes the problem, as the front wheels lock up before the back wheels do, and the car sees that as the front wheels hitting ice before the back wheels do.
A good test would be for someone to beef up the back brakes more than they would normally, and then see if the car still enters into ice mode when a person locks up the brakes.
I still believe it is simply time from brake pressed to time of lockup, and if thats too short of a time, it determines ice mode. However, I would prefer you be correct that it is the front wheels relative to the back wheels, as that is a problem we can then solve.
A good test would be for someone to beef up the back brakes more than they would normally, and then see if the car still enters into ice mode when a person locks up the brakes.
I still believe it is simply time from brake pressed to time of lockup, and if thats too short of a time, it determines ice mode. However, I would prefer you be correct that it is the front wheels relative to the back wheels, as that is a problem we can then solve.
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02-20-2019, 02:27 PM
#110
If your front brakes lift enough weight off the back wheels bigger rear brakes will just make the situation worse. It's more likely a combo of aggressive braking and weight transfer. I haven't had it happen yet and I have the 390mm AP front brakes on mine and the standard AP rears. I don't stomp the brakes though I try to apply them as smoothly and quickly as I can.
Thus, if the back tires locked just as quickly as the front tires when a person jabs the brakes, then that would perhaps cure it. The second person who spoke above actually mentions trying this on another vehicle, with successful results. He tamed the front brakes and enhanced the rears. He said it then was better remedied.
The trade off of course is... does the car now handle like s*** in a curve when hitting the brakes, and the back end unhooks and wants to come around every time, once this rear brake upgrade is performed?
Last edited by Mikec7z; 02-20-2019 at 02:29 PM.
02-20-2019, 03:03 PM
#114
Drifting
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2020 Corvette of the Year Finalist (track prepared)
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I experienced it at MSRH right before "The launch" in a C7 Z51 with the J56 Z06 brakes.
It happened 3 times over the weekend I ended up braking earlier and softer to eliminate it.
Hoosier R7s with Hawk DTC70
It happened 3 times over the weekend I ended up braking earlier and softer to eliminate it.
Hoosier R7s with Hawk DTC70
02-20-2019, 03:03 PM
#115
Melting Slicks
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2020 Corvette of the Year Finalist (track prepared)
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Not so much with Factory CCBs, those came off my car pretty much immediately.
BUT, for testing I removed the AP brakes and am back on factory CCBs. I plan to run those a few events this year for the Optima series and see if I have any better luck. I've been on the AP racing stuff since it came out. The brakes are fantastic for road course, I just don't think I have the right combination for autocross, which is imperative for the stuff I'm doing.
BUT, for testing I removed the AP brakes and am back on factory CCBs. I plan to run those a few events this year for the Optima series and see if I have any better luck. I've been on the AP racing stuff since it came out. The brakes are fantastic for road course, I just don't think I have the right combination for autocross, which is imperative for the stuff I'm doing.
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02-20-2019, 03:05 PM
#116
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Yeah autocross is a whole different scenario. Pads have to be ready from the word go. I haven't autocrossed mine at all so I'm not sure what the results would be doing that. That might put me in ice mode as well.
02-20-2019, 03:07 PM
#117
i think a quick way to test this theory would be to run a more aggressive track pad on the back brakes, and leave the front ones stock pads. At that point, see if it is better prohibited when jabbing the brakes, trying to initiate it. If so, then we can start to brainstorm a better alternative. Maybe the rears need a larger rotor? This would be good info for aftermarket brake companies to know about who make kits for these cars.
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pkincy (02-21-2019)
02-20-2019, 06:53 PM
#118
I still don't fully understand what "ice mode" is. I presume it is when you have consecutive hard brake applications and the second application gives you a hard peddle but no hydraulic pressure so no braking. But how close in time do the applications have to be to experience it? A 15 second time spread? A 10 second time spread? A 5 second time spread? A less than 3 second time spread? Is it caused by the ABS system? Is it caused by the piston in the hydraulic cylinder not having time to cycle properly so you are back at full hydraulic pressure? Everybody just complains about "ice mode" with no analysis of the root cause. I would guess that autox would show "ice mode" much more often than HPDE or road racing as the turns are so much closer together. In fact in some situations as you know the brake applications are very close together in time. Say an offset box or Chicago box.
If it is caused by the ABS system, can pulling the ABS fuse defeat the ABS so that you can try good old threshold braking to see if that keeps you out of the "ice mode?" Quite obviously there are a number of people very successfully autoxing cars without ABS. In my race car, the class rules were that ABS had to be removed or if you didn't want to lose the weight you could simply pull the ABS fuse. It took a bit but soon we all learned how to threshold brake just fine. That is one solution if it is the ABS system. If it is the hydraulic cylinder piston that is a horse of a different color, particularly if you are running a class that allows no modification to the oem hydraulic cylinder. Prior to going road racing I autocrossed competitively for several years with some seriousness (52 weekends autocrossing by driving all over the West in my rookie year). In those days the problem was the master cylinder piston time cycle. And there was nothing we could do in my class (FS). So we had to learn to drive around the problem. At that time the master cylinder piston took about 3 seconds to cycle and rebuild full hydraulic pressure. So you simply had to know that you weren't going to get to full brake pressure applications in less than 3 seconds. So you generally had to overbrake on the first of 2 consecutive braking segments so that you could make the second turn without problem.
Once you identify the source of the problem you will be able to figure out a solution. My reading of Tadge's answer is that it is in the ABS programming. If that is the case, what is the best way to defeat ABS in a C7?
BTW, my lesson for learning threshold braking was in my first road race. It was at AutoClub Speedway and was braking from 150 to 65 into Turn 3 in the morning warm up session on a set of brand new race tires. I flat spotted the fronts so bad I darned near lost my teeth running the rest of the weekend on those tires. They must have been near square from that flat spotting and running the roval with square tires was a bit bumpy. But it was a good enough lesson that I generally could max brake after that without tire smoke appearing.
If it is caused by the ABS system, can pulling the ABS fuse defeat the ABS so that you can try good old threshold braking to see if that keeps you out of the "ice mode?" Quite obviously there are a number of people very successfully autoxing cars without ABS. In my race car, the class rules were that ABS had to be removed or if you didn't want to lose the weight you could simply pull the ABS fuse. It took a bit but soon we all learned how to threshold brake just fine. That is one solution if it is the ABS system. If it is the hydraulic cylinder piston that is a horse of a different color, particularly if you are running a class that allows no modification to the oem hydraulic cylinder. Prior to going road racing I autocrossed competitively for several years with some seriousness (52 weekends autocrossing by driving all over the West in my rookie year). In those days the problem was the master cylinder piston time cycle. And there was nothing we could do in my class (FS). So we had to learn to drive around the problem. At that time the master cylinder piston took about 3 seconds to cycle and rebuild full hydraulic pressure. So you simply had to know that you weren't going to get to full brake pressure applications in less than 3 seconds. So you generally had to overbrake on the first of 2 consecutive braking segments so that you could make the second turn without problem.
Once you identify the source of the problem you will be able to figure out a solution. My reading of Tadge's answer is that it is in the ABS programming. If that is the case, what is the best way to defeat ABS in a C7?
BTW, my lesson for learning threshold braking was in my first road race. It was at AutoClub Speedway and was braking from 150 to 65 into Turn 3 in the morning warm up session on a set of brand new race tires. I flat spotted the fronts so bad I darned near lost my teeth running the rest of the weekend on those tires. They must have been near square from that flat spotting and running the roval with square tires was a bit bumpy. But it was a good enough lesson that I generally could max brake after that without tire smoke appearing.
02-21-2019, 12:30 PM
#119
And here are 2 more short clips of 2 of those other drivers in my car, experiencing Ice Mode....
https://youtu.be/2jHO_I8Y6Q0
https://youtu.be/AOUCxz8XAqU
https://youtu.be/2jHO_I8Y6Q0
https://youtu.be/AOUCxz8XAqU
Is this ice mode?
Perhaps I am missing something...... but what is wrong with somewhere North of a 1.25g deceleration with half the brake pedal applied?
I saw this in all 3 of these clips.
Last edited by dar02081961; 02-21-2019 at 05:53 PM.
02-21-2019, 12:34 PM
#120
Safety Car
On initial application the G curve was at about 0.2 g deceleration. It didn't hit 1.25 until the car had slowed markedly. the second video the initial bite was about 1 g but clearly the brakes were not showing full application and the car was not stopping.
Last edited by pkincy; 02-21-2019 at 12:36 PM.