NTMD8R

Yes, I am thinking the after-market pads have contributed to this.
So I am going back to the OEM pads.

I also have asked if any non-Z06 drivers have experienced this "ice mode", on the C7 Tech forum.

It will be interesting to see if this is only a Z06 issue, or not.

fleming23

While I don't have anything on paper to prove it, I have been told by a GM track/race car builder that the Z07 ABS module does have a different programming than the base programming. That said, my Z07 ABS module still goes into ICE mode with my aftermarket brake/tire combination.

Mikec7z

i had heard this as well, and thats why i jumped onto the idea their abs ice mode configurations were most likely different from the NON z07's. They still may be different, but it appears, not different enough to solve the false ice mode initiation.

TrackAire

I don't have experience with the C7 platform, but I'm thinking that the ice mode happens when the a speed ratio between the front and rear tires exceeds a preset parameter and the front brakes just don't give full pressure to allow the front tires to roll at near the speed of the rear tires. Does this sound correct?.....I can't see what other parameters the pcm is using other than the speed sensors from each corner of the car.

Since you autocross, a "semi-safe" experiment you can try is a larger rear tire to increase rear tire to front tire height ratio. Last calculations I did on my C5Z06 on stock tire sizes was the rears are 2.68% taller than the fronts. I've been running a square setup of 295/30/18 which means a 0% difference in front to rear tire speeds. I'm thinking of trying a set of 305/35/18 tires for the rear. That would give me a 5.30% diameter difference between front and rear tires....twice the stock front to rear ratio difference that the pcm is programmed for. So my rear tires would be rotating slower as the pcm see's it compared to the fronts, theoretically giving me more leeway in case the fronts reduce rotation too fast in relationship to the rears (at least that is what my brain is thinking....no promise that I'm right). Once the taller rear tires are installed you could try to induce ice mode and see if it made a difference or helped reduce it. Just a mechanical idea to try.....no way you're going to get anywhere regarding changing the abs program. Heck, the engineer that wrote the ice mode algorithm may not even work there anymore, lol.

As a side note I've encountered ice mode twice in my bone stock 2016 F350 Superduty....both times when somebody ran a light or did a bonehead move where I had to take evasive action and nail the brakes to avoid T boning them. The conditions were warm and dry and the truck was fully warmed up and had been driven for many miles. It almost felt like the the truck freewheeled as I was pressing the brake pedal nearly as hard as I could. Very dangerous regardless of what you drive....but it does happen under the right conditions more often than I think is realized.

Mikec7z

your theory could be correct, but i think it might be simpler.

When you are on ice... and you hit your brakes... and all 4 (or any 1 or combination of) tires lock up without problem...

this lock up happens very quickly from the moment you touch the brakes.

I believe, GM and abs systems in general for all makes of cars, have a time threshold, and it is the time from the moment the brakes are pushed to the time the tires lock up...

and if that time is too short, THEN the car DECIDES it is on ice.

And of course, it goes into ice mode, where all 4 wheels get 30% braking power, to try to keep the car smooth and steady as it decelerates at a "possible" rate for an icy surface.

The problem of course is, this minimum time from the moment brakes are first pushed to the moment all 4 wheels stop spinning or reduce x amount in speed, can also be achieved when NOT on ice. (stabbing the brake pedal as hard as one can, and getting from 0 brake pressure, to 100% which is enough to lock up the tires, and also within the time threshold)

And that of course is what we have all discovered. And of course, stronger brake pads, aggravate the situation further, as they can lock up all 4 tires in the blink of an eye, and also, when the brake pedal is not as depressed as the factory abs system assumes it needs to be, to accomplish all 4 tires slowing to x speed in the blink of an eye.

And thus, ice mode.

So just as we need an aftermarket tuner to adjust our air fuel trims on our cars with bigger blowers and fuel systems... we need an aftermarket tuner to adjust our ice mode thresholds on our abs systems.

I hope someone comes forward who has enough knowledge to try to take a stab at solving this.

NTMD8R

I would like to know what differences there are between C6 Z06 and C7 Z06 ABS systems.
I would also like for someone to tell us just how the ABS works...
Is the computer a part of the car computer, or is it separate and part of the ABS box?
What logic algorithm is employed with this computer?

I don't necessarily care to get in and "tune" it; I just want to know how it works.

Mikec7z

i can say with 99.99 percent certainty, it is a very long and complex algorithm, if it is only a single one. Chances are there are MANY multiple scenarios it is watching for, not just one.

I bet the c6 does it also, but again, most dont have brake pads strong enough on those cars to make it occur... unless you are in fact on ice, so the wheels all do lock up easily.

This has been on cars for a while, a person with a jeep had it happen to them, and their jeep was at least 4 years old. Logic would tell me the c6 had it as a problem too, but i am not certain.

NTMD8R

Mike, I only mention the C6 because.......
I autocrossed a 2007 Z51 convertible from 2008 through 2014... all under the same conditions we now autocross under.
I put after-market coil-overs, sway bars, wheels, and sticky tires on it.
NEVER once did I experience ice mode.... nor did anyone else driving the car
We also had the 2008 Z06 all during 2017, with different wheels and sticky (Hoosier) tries, and Ferodo DS2500 brake pads, and koni shocks, etc., etc.
NEVER once did I experience ice mode.... nor did anyone else driving the car

I AM an aggressive driver... why is my C7 now doing this?????? and to other drivers too.

Poor-sha

Check the A&RR section. I'm pretty sure there were reported cases with the C6.

Mikec7z

Come to think of it, you are correct, c6z did not have it... i know because i was trapped on top of a mountain, coming down it, when it started to snow, and it was regular abs, not ice mode Unless i just never jabbed them hard and instead was going as easy as i could (also possible)

I have read that it was reported as well on the c6z, but if poorsha is right, and it did have it, it was much more lenient before it would activate relative to the c7z i believe, as i never experienced it on my c6z.

NTMD8R

Check this thread out in the A&RR forum.....

https://www.corvetteforum.com/forums...-ice-mode.html

And this one...

https://www.corvetteforum.com/forums...-ice-mode.html

And this one.....

https://www.corvetteforum.com/forums...ere-a-fix.html

And on another site.....

https://www.z06vette.com/forums/f5/c...ce-mode-17684/


So this has been around for some time.
And the only solution is to PROGRESSIVELY apply brakes.
I'll definitely have to change the way I race

Mikec7z

understand the progression tho...

all you have to do is get your brake lights to light up... just have the brake on 5%, to where it is not even slowing you down, then if you jab it to 100% even a half second later, you should NOT have ice mode.

Ice mode is a clock/timer i believe... from the moment you initiate ANY brake pressure, to the moment the wheels stop spinning, so by barely touching the brakes a moment before your real breaking point, you will be fine. This is why most people dont experience it, most do touch their brakes a moment before they really push them down 100%.

only in emergency situations do people really jab them from 0 to 100%, instantly, and that is when the ice mode is happening.

badhabit_wb

Probably why I've never had it even with the 390mm big brake kit. I always put a little pressure on before I get on them hard. Too many years on cars without abs I guess.

NTMD8R

OK, we autocrossed today with the OEM pads.... but it was RAINING.... as in REALLY Wet downpour for our first morning runs..
For this, we changed the wheels/tires yesterday to the OEM rims with Conti ExtremeContactSports.

At no time did I experience Ice Mode.... mind you, in the rain, I had to be VERY Smooth,
and brake a bit early (therefore not as aggressive) and carry a bit of trail braking, and brake a little less harder.
I did notice the brakes weren't quite as responsive as with the after-market pads we had on earlier.
So I did have to apply them a little earlier.

The afternoon runs were a little bit dryer... it almost stopped raining, and even got a few dry patches on the pavement,
but it did continue to spit somewhat.

Coincidently I had FTD at 44.9, and my wife had next at 45.1... this was out with the local Porsche group.

I don't think the rain is a good concluding scenario to say I have "licked" Ice Mode,
but it sure was a good feeling to not experience it at all today.

We have another event next Sunday, and another one the Sunday after that.
Hopefully we'll have better weather, and that will be a better test environment.

fleming23

Do you plan on leaving everything stock for the next events as well?

NTMD8R

Yup, leaving OEM pads in, and will use either the contis or the rivals, depending on the weather

Larry M

Bill Dearborn

People call the situation ICE Mode but it truly doesn't have anything to do with ice. They have to program the system to work on all sorts of friction surfaces, ice being just one of them. You can get a similar situation as ice if you run across spilled oil, antifreeze, gravel or wet leaves. On all of those types of material I have had proper ABS action. When you apply the brakes on an icy surface the pedal starts to vibrate, the individual wheel brake calipers have brake pressure released as the wheels start to lock up and once they are rolling properly the brake pressure is reapplied. Each wheel is controlled separately from all of the others except for one condition. A normal stop. ABS doesn't react since all wheels are rotating properly and as the car comes to a stop all wheels stop at once. ICE Mode isn't like any of those situations and is not a normal operation of any ABS system, however, it is an unintended consequence of all the things they have to take into account. I haven't had it happen to me with my C7 but did have it happen several times with my C6Z. I got a very hard brake pedal without any vibrations (that alone tells you the ABS isn't doing its thing as the vibrating pedal is the mechanism used to tell the driver the ABS is functioning), the car didn't slow very well and there wasn't the usual groaning sound that comes with ABS operation or the violent vibrating of the whole car you get when the ABS is functioning during a hard stop on dry pavement. All I had was a hard solid brake pedal and the feeling of no brakes. After we sailed off T1 at VIR at about 90 mph even my passenger asked why I didn't use the brakes, however, we did slow from about 140 mph to 90 before we were on grass.

Bill

NTMD8R

So we did another Autocross today... 90 drivers... in the rain in the morning.
Fortunately we were in the 3rd run group, so we got to run last in the morning, and last in the afternoon.

I did experience Ice Mode on my first lap in the morning while heading into a left hand sweeper, heading for the home stretch.
But I did know what it was immediately, and let off, then re-applied again, and saved the turn (barely).

We did have better conditions than the first and second groups, being in the 3rd group, since the rain did ease up.
Therefore for the afternoon runs, it did start to dry up considerably, and we had the driest pavement at the end.
I tried very hard to apply the brakes smoothly and not aggressively, and that worked very well.
I was also able to use considerable trail braking on the course, which also helped.

So, my "findings".... the OEM pads work very well, and learn how to use the brakes on this car so you do not
experience Ice Mode.

Oh yeah, the tires we were using today (again... rain), were the Continental ExtremeContactSport....
OEM tires sizes.

I did FTD with my last run (43.7... next closest was 44.0... on Hoosier rain tires).
My wife did a 45.7... she was 7th fastest today.
This was my last run... and I WAS quite Exuberant at the end.

Toysrus

I have commented on this before but have a new perspective after running at this year's SCCA Solo Nationals. I own a C7Z and have been frustrated by what I thought was ICE mode. Turns out, there are two braking problems in the C7Z and from my experience, both are related to left foot braking. One issue results in a rock hard pedal with very little travel and is most likely caused by a loss in vacuum assist. This would be a particular issue for the supercharged variants. My guess is the very quick transition from gas to brake, if repeated a number of times over an autocross run, depletes the vacuum and you get the hard pedal and blow through the corner.
The second issue is most surely ICE mode and the pedal feels soft as opposed to hard. I had the opportunity to run a 2018 Camaro SS 1LE in the CAM Challenge in Lincoln and experienced it CONSTANTLY. My feeling is again, with left foot braking, one of the car's ECU's sees input from both the brake and the accelerator and freaks out. My first fix was to switch back to right foot braking...which was a complete competitive disaster on my part and then subsequently to switch back to left foot braking but deliberately count to 1 from the time i released the gas to the time I hit the brake. Doing this, regardless of how aggressively i applied the brake or how hard i depressed the pedal, kept ICE mode at bay. I ended up posting the second fastest time in CAMC qualifying .08 seconds off the leader.

My hope is to find an electric vacuum assist for the Z06 and see if that solves my hard pedal problem. I am thinking an ABS tune is what needed for an ICE mode remedy.