[GunMetalGrey]

Originally Posted by khcoaching

Yeah, this is tough. The system needs to reset and the only way that happens is to release the brake and try again, the opposite of what your brain is screaming. Pushing harder only makes it worse.

Ken

Good to know! Yes hard to do...

[GunMetalGrey]

Originally Posted by Christian1LE

The slicks were 315/30/18 so they are slightly smaller diameter than OEM. Driving exactly the same every lap. I'm going to be at VIR this weekend for hyperfest and I'm going to keep a close eye on it to see if I can completely eliminate it by braking slightly less aggressive on initial pedal input. I also ordered DTC 60's for the rear to see if that helps the issue at all.

I'm going to do the same thing as you for braking input.

I ordered Hawk HT10 for the rear which seem to be the next step down from the DTC60's based on the graphs they provide, not the DTC50

I'm thinking maybe Cobalt XR2's for the front as a slightly lower friction pad for the front for me, or a Hawk DTC60 for you

[Christian1LE]

Originally Posted by GunMetalGrey

I'm going to do the same thing as you for braking input.

I ordered Hawk HT10 for the rear which seem to be the next step down from the DTC60's based on the graphs they provide, not the DTC50

I'm thinking maybe Cobalt XR2's for the front as a slightly lower friction pad for the front for me, or a Hawk DTC60 for you

One strange thing I've noticed is that with the DTC60's up front and the XP12's at the rear I'm getting very little wear on my rear pads about 50% of what I usually see. My Xp12's on the rear usually last 800 miles. I went to change them last weekend and they still had half their life left (after 800 miles). So maybe I'm thinking that might have something to do with it, but maybe not.

[DaveC113]

Originally Posted by GunMetalGrey

I read something on the Corvette forum that seems to make sense; with stickier pads the car locks up the tires more easily with less brake effort, hence the system thinks you are on ice... however this does not seem to make sense with stickier tires. Can you elaborate on why the change alone would cause more ice mode when both the brake and tires increase in grip?

It's more that running a square setup eliminates the differential in wheel speed front to rear the EBCM expects to see. It's a differential in wheels speeds that causes ice mode, so running a square setup is more likely to trigger it because the fronts are rotating slower than expected vs the rears.

Ice mode is called ice mode because it's there to prevent brake input causing a spin if half the car is on ice and the other half is not.

So in the same way mismatching brake pads is also a bad idea, the OEM system uses the same brake pads front and rear. If there's a difference in brake pad mu (coefficient of friction) front to rear you're just asking for problems with ice mode because the difference in mu is very likely to result in differences in wheel speed the EBCM isn't programmed for, and the more abrupt the initial application of brakes the more likely this will happen too.

Same with applying the brakes abruptly if the car is unsettled due to a bumpy surface or the the way the track is laid out. This is why ice mode is more likely in autox, you often have to brake when the car is still unsettled from the last element or combined with steering input.

Finally, there is also a brake limiting phenomenon that has to do with a combination of steering input, brake input and speed that the car figures is likely to have you end up in spin. This is where stickier tires may lead to brake limiting, you are exceeding the parameters of grip and handling the car is programmed for and it's trying to keep you from making a horrible mistake. But this isn't ice mode, it just has a similar result, limited braking.

IMO #khcoaching may be experiencing this and not ice mode. Ice mode, once I switched to the '19+ EBCM is momentary, but brake limiting due to asking the car to simultaneously steer and brake above and beyond what the OEM systems are programmed for is much more likely than ice mode, especially if you're not seeing front/back or side to side wheel speed differences as triggers.

In any case, a more gradual initial brake application is the solution, as well as running the same brake pads front and rear and using smaller diameter front vs rear tires.

Or just buy a ZLE, it seems that car's electronics have none of these issues.

[GunMetalGrey]

Originally Posted by DaveC113

It's more that running a square setup eliminates the differential in wheel speed front to rear the EBCM expects to see. It's a differential in wheels speeds that causes ice mode, so running a square setup is more likely to trigger it because the fronts are rotating slower than expected vs the rears.

Ice mode is called ice mode because it's there to prevent brake input causing a spin if half the car is on ice and the other half is not.

So in the same way mismatching brake pads is also a bad idea, the OEM system uses the same brake pads front and rear. If there's a difference in brake pad mu (coefficient of friction) front to rear you're just asking for problems with ice mode because the difference in mu is very likely to result in differences in wheel speed the EBCM isn't programmed for, and the more abrupt the initial application of brakes the more likely this will happen too.

Same with applying the brakes abruptly if the car is unsettled due to a bumpy surface or the the way the track is laid out. This is why ice mode is more likely in autox, you often have to brake when the car is still unsettled from the last element or combined with steering input.

Finally, there is also a brake limiting phenomenon that has to do with a combination of steering input, brake input and speed that the car figures is likely to have you end up in spin. This is where stickier tires may lead to brake limiting, you are exceeding the parameters of grip and handling the car is programmed for and it's trying to keep you from making a horrible mistake. But this isn't ice mode, it just has a similar result, limited braking.

IMO #khcoaching may be experiencing this and not ice mode. Ice mode, once I switched to the '19+ EBCM is momentary, but brake limiting due to asking the car to simultaneously steer and brake above and beyond what the OEM systems are programmed for is much more likely than ice mode, especially if you're not seeing front/back or side to side wheel speed differences as triggers.

In any case, a more gradual initial brake application is the solution, as well as running the same brake pads front and rear and using smaller diameter front vs rear tires.

Or just buy a ZLE, it seems that car's electronics have none of these issues.

Thank you for the very detailed response!

This definitely did start occurring a lot more once I started using the 19 inch wheel and tire ZLE set up… (both wheels and tires are exactly half an inch less diameter front and rear though so they the difference between front and rear vs OEM would be very little from a percentage context)

Sounds like I should get an EBCM ABS brake module from
a 2019+ ZLE then, not just a 2019+ ZL1 so that the overall wheel diameters match the calibration exactly (or go with stock OEM sized R compound tires for the track)
And change my driving style

However, I’m still not sure why Ken would be having so much trouble if it’s not Ice Mode, but I will await more clarification from him, however, based on what you said, it seems like slicks could help prevent ice mode by keeping the car more settled as long as they are the same size diameter as stock OEM (though I know his sizing is not stock)

Also, I guess you are saying that cars with stock OEM tire diameter should be getting it less but will still get it (as referenced by the many drivers with stock set up but still getting it). There seems to be a lot of guys on the Corvette forum with stock Corvettes that still have this issue a lot. So it seems to me that driving style must be a single biggest factor.

[DaveC113]

Originally Posted by GunMetalGrey

Thank you for the very detailed response!

This definitely did start occurring a lot more once I started using the 19 inch wheel and tire ZLE set up… (both wheels and tires are exactly half an inch less diameter front and rear though so they the difference between front and rear vs OEM would be very little from a percentage context)

Sounds like I should get an EBCM ABS brake module from
a 2019+ ZLE then, not just a 2019+ ZL1 so that the overall wheel diameters match the calibration exactly (or go with stock OEM sized R compound tires for the track)
And change my driving style

However, I’m still not sure why Ken would be having so much trouble if it’s not Ice Mode, but I will await more clarification from him, however, based on what you said, it seems like slicks could help prevent ice mode by keeping the car more settled as long as they are the same size diameter as stock OEM (though I know his sizing is not stock)

Also, I guess you are saying that cars with stock OEM tire diameter should be getting it less but will still get it (as referenced by the many drivers with stock set up but still getting it). There seems to be a lot of guys on the Corvette forum with stock Corvettes that still have this issue a lot. So it seems to me that driving style must be a single biggest factor.

I doubt a ZLE EBCM would be compatible as ZLEs don't have MRC and are otherwise very different cars, but who knows. I was originally going to try it but the GM engineer said its gotta be from the same exact car.

On tire diameter what matters is front vs rear % difference.

On stickier tires, what it seems to me is going on is brake limiting based on vehicle speed and steering input vs requested braking forces. The issue is, this is one of those situations where allowing full brake forces could be the cause of a spin. So just like ice mode, it's saving you from yourself in that it won't allow the brakes to be the cause of a spin, and the only solution is to have the ABS system limit brake application. Stickier tires allow a driver to exceed the ABS system's parameters safely, but the car's ABS system is calibrated for the OEM tires.

So the result of brake force limiting is involved in both ice mode and speed/steering angle based brake limiting, but the causes are different... ice mode is based on wheel speed differences and the other is based on lateral g-forces, speed, and requested brake forces. The solution to both issues in terms of driving technique is the same though, less abrupt brake application especially if any steering input is involved, the car is unsettled or the surface is bumpy enough.

[N Camarolina]

Ken, in building off of Dave's thoughts about it not being ICE mode, is it possible that what you are experiencing is just the ABS activating normally in response to what the system thinks is pending wheel lock up? ABS pulsing the brakes does not have the same stopping power as true threshold breaking, so maybe the braking rate you experience in ABS mode feels poor enough that you think it's ICE mode?

I ask because in this car, it's much harder for me to detect/perceive the ABS activating under braking. The pedal does not pulse like all the other grocery getter vehicles I've driven. I too have had ABS activate occasionally during trail braking, but I only know this because of the PDR data, not because I could feel it in the pedal.

[GunMetalGrey]

Originally Posted by DaveC113

I doubt a ZLE EBCM would be compatible as ZLEs don't have MRC and are otherwise very different cars, but who knows. I was originally going to try it but the GM engineer said its gotta be from the same exact car.

On tire diameter what matters is front vs rear % difference.

On stickier tires, what it seems to me is going on is brake limiting based on vehicle speed and steering input vs requested braking forces. The issue is, this is one of those situations where allowing full brake forces could be the cause of a spin. So just like ice mode, it's saving you from yourself in that it won't allow the brakes to be the cause of a spin, and the only solution is to have the ABS system limit brake application. Stickier tires allow a driver to exceed the ABS system's parameters safely, but the car's ABS system is calibrated for the OEM tires.

So the result of brake force limiting is involved in both ice mode and speed/steering angle based brake limiting, but the causes are different... ice mode is based on wheel speed differences and the other is based on lateral g-forces, speed, and requested brake forces. The solution to both issues in terms of driving technique is the same though, less abrupt brake application especially if any steering input is involved, the car is unsettled or the surface is bumpy enough.

I put a traction control module in from a ZLE auto and it seems to work fine for my car, so I’m hoping the same is true for the braking module, as soon as I find a used one, I’ll test it out and let everyone know.

As for tire diameter, yeah, that was confusing to me, as soon as I went to 19 inch wheels and tires This problem increased greatly however, the percentage difference in diameter between the front and the rear is actually still the same as with the 20 inch tires. And the compound was the same since I had the SC3R tired and 20 inches well…

The only thing that seems to be totally consistent here, at least, in my opinion, is breaking input, since multiple members have said when they changed their driving style this solved the problem. But I really don’t want to lose lap time because I’d be applying the brakes earlier and more gradually…

I just reread the other ice mode thread, just to be super clear Dave C113, when you swapped in a 2019 ABS module, it got rid of any ice mode problems for you? Or just reduced the severity of them? Or did you also have to change your driving style as well?
Have you been to more than two events since changing your EBCM as per your August 11th post from 2022? (I’d prefer a large sample size instead of small sample size just to make sure.)

[GunMetalGrey]

Originally Posted by N Camarolina

Ken, in building off of Dave's thoughts about it not being ICE mode, is it possible that what you are experiencing is just the ABS activating normally in response to what the system thinks is pending wheel lock up? ABS pulsing the brakes does not have the same stopping power as true threshold breaking, so maybe the braking rate you experience in ABS mode feels poor enough that you think it's ICE mode?

I ask because in this car, it's much harder for me to detect/perceive the ABS activating under braking. The pedal does not pulse like all the other grocery getter vehicles I've driven. I too have had ABS activate occasionally during trail braking, but I only know this because of the PDR data, not because I could feel it in the pedal.

I think Ken , who is a driving coach, absolutely definitely knows the difference between these two things… he has mentioned his disappointment in himself for activating ABS many times in his threads, so he’s very familiar with it and clearly tries to avoid it as much as possible, where as a less Skilled driver like me, just mashes the brake pedal haha

As for noticing the difference between what Dave C113 said and ice mode, thats probably another story since it seems like the same end result from a different cause

[khcoaching]

Originally Posted by DaveC113

It's more that running a square setup eliminates the differential in wheel speed front to rear the EBCM expects to see. It's a differential in wheels speeds that causes ice mode, so running a square setup is more likely to trigger it because the fronts are rotating slower than expected vs the rears.

Ice mode is called ice mode because it's there to prevent brake input causing a spin if half the car is on ice and the other half is not.

So in the same way mismatching brake pads is also a bad idea, the OEM system uses the same brake pads front and rear. If there's a difference in brake pad mu (coefficient of friction) front to rear you're just asking for problems with ice mode because the difference in mu is very likely to result in differences in wheel speed the EBCM isn't programmed for, and the more abrupt the initial application of brakes the more likely this will happen too.

Same with applying the brakes abruptly if the car is unsettled due to a bumpy surface or the the way the track is laid out. This is why ice mode is more likely in autox, you often have to brake when the car is still unsettled from the last element or combined with steering input.

Finally, there is also a brake limiting phenomenon that has to do with a combination of steering input, brake input and speed that the car figures is likely to have you end up in spin. This is where stickier tires may lead to brake limiting, you are exceeding the parameters of grip and handling the car is programmed for and it's trying to keep you from making a horrible mistake. But this isn't ice mode, it just has a similar result, limited braking.

IMO #khcoaching may be experiencing this and not ice mode. Ice mode, once I switched to the '19+ EBCM is momentary, but brake limiting due to asking the car to simultaneously steer and brake above and beyond what the OEM systems are programmed for is much more likely than ice mode, especially if you're not seeing front/back or side to side wheel speed differences as triggers.

In any case, a more gradual initial brake application is the solution, as well as running the same brake pads front and rear and using smaller diameter front vs rear tires.

Or just buy a ZLE, it seems that car's electronics have none of these issues.

Awesome post!

HA! I haven't had the ZLE out yet to test...soon.

I understand ABS and this isn't ABS, at least ABS as I have experienced it. ABS can be played with....ABS can be initiated and typically you can release the brake, it disengages immediately and then brake pressure can be reestablished again. The issue I am having seems to require a near full reset with almost total release of the brake, then reapplying. This issue happens earlier than when ABS intervention should happen imo.

To your point, I think you are spot on with how sensitive this issue can happen in relation to how you apply the brake with updated brakes, tires, square setup etc.

So.....I looked at a ton of data this morning, looking for brake application differences. See next post -

[khcoaching]

Another data dump!

As we all know, the faster you go, the less time you have. Meaning, if you are traveling the same distance in less time, you have to either - 1) Start your processes earlier 2) Use more force. For sure there is a ratio where one is faster than the other, which makes this sport so hard!

I looked a lot of data, focusing on where the issue happens and what my motor controls looked like. I also did this with all the different tires I have run, plus when Randy Pobst drove my car. (BTW, his first comment was how outstanding the brakes were)

The consensus is - Initial brake application where I apply the brakes in UNDER .4 of second can induce this. Brake applications OVER .4 it seems to not be an issue, regardless of the pressure. When applying them at .4 or under and we stay at say 1000-1200 psi or lower, no issue. When going over 1200, it seems to be more prevalent. I think the answer is to be precise with initial brake application when at pace.

Note - IME, .3-.4 is an acceptable amount of time for a brake build when hauling ass. Less than .3 is where we call it abrupt.

Here we go where I am looking at how long it takes to build brake pressure. (Times are close and I concentrated on the initial build until it stopped it's initial upward movement)

#1 - Z214s at .3 at different brake pressures



#2 Same as #1, different corner



#3 Toyo RR - .45 application RANDY POBST driving



#4 Best 3S - .45 application



#5 Best Toyo RR - .60



#6 Best 3R -.80

[Christian1LE]

Originally Posted by GunMetalGrey

I put a traction control module in from a ZLE auto and it seems to work fine for my car, so I’m hoping the same is true for the braking module, as soon as I find a used one, I’ll test it out and let everyone know.

As for tire diameter, yeah, that was confusing to me, as soon as I went to 19 inch wheels and tires This problem increased greatly however, the percentage difference in diameter between the front and the rear is actually still the same as with the 20 inch tires. And the compound was the same since I had the SC3R tired and 20 inches well…

The only thing that seems to be totally consistent here, at least, in my opinion, is breaking input, since multiple members have said when they changed their driving style this solved the problem. But I really don’t want to lose lap time because I’d be applying the brakes earlier and more gradually…

I just reread the other ice mode thread, just to be super clear Dave C113, when you swapped in a 2019 ABS module, it got rid of any ice mode problems for you? Or just reduced the severity of them? Or did you also have to change your driving style as well?
Have you been to more than two events since changing your EBCM as per your August 11th post from 2022? (I’d prefer a large sample size instead of small sample size just to make sure.)

You actually will not necessarily lose laptime by braking earlier and softer. You can still maintain the same average speed in that distance vs braking hard and late. You would just suffer in race situations where someone is trying to pass you. I don't have any data to back this up in the real world but it works in simulators. (Comparing data vs real life drivers). The most important thing is always to carry as much speed as possible into the corner without overslowing.

[khcoaching]

Originally Posted by Christian1LE

You actually will not necessarily lose laptime by braking earlier and softer. You can still maintain the same average speed in that distance vs braking hard and late. You would just suffer in race situations where someone is trying to pass you. I don't have any data to back this up in the real world but it works in simulators. (Comparing data vs real life drivers). The most important thing is always to carry as much speed as possible into the corner without overslowing.

And, not ruining your exit.

Great thought and you have the right idea. Though....It depends on the individual corner. At The Ridge as an example, T6,T8 you can do that because the radius is more open and you can carry more overall speed into the slow point. T1 T13 and even T11, where the radius is tighter, braking later for sure has time as backed up by data.

Ken

[DaveC113]

Originally Posted by khcoaching

Awesome post!

HA! I haven't had the ZLE out yet to test...soon.

I understand ABS and this isn't ABS, at least ABS as I have experienced it. ABS can be played with....ABS can be initiated and typically you can release the brake, it disengages immediately and then brake pressure can be reestablished again. The issue I am having seems to require a near full reset with almost total release of the brake, then reapplying. This issue happens earlier than when ABS intervention should happen imo.

To your point, I think you are spot on with how sensitive this issue can happen in relation to how you apply the brake with updated brakes, tires, square setup etc.

So.....I looked at a ton of data this morning, looking for brake application differences. See next post -

Agreed, it's not ABS anti-lock, it's the ABS system limiting overall brake force application to avoid a spin caused by braking while the vehicle is experiencing lateral g-forces. When it does this it's at the very beginning of brake application, nowhere near lockup.

If you're not seeing wheel speed differences ft/rear or side/side in the data as a trigger for brake force limiting, and the force limiting is more than momentary, then I'd think it's likely not ice mode, but exceeding the lateral-g / brake force limits that the car thinks is going to cause a spin. It feels like ice mode but what triggers it isn't the same.