I wanted to record what lead to Ice Mode on the track for me this past weekend. Ice mode for me was a rock hard pedal and about 25% braking. I have had about every other kind of brake failure from fluids and pads, and it was like none of those, so don't go there. Solved completely and consistently, but releasing the brake completely and reasserting slowly. I could make it happen on any high braking zone if I wanted to or make it not happen depending on how I applied the brakes. I did not leave the track surface, but it was scary the first time it happened. Since I have heard about Ice Mode for over 10 years on this forum and others, I was able to overcome it. Thanks to all who previously reported this.
I know this has been covered extensively, just wanted to highlight the trigger mode that lead to it.

Background:
2005 Boxster S (987.1)
Tracked since 2007, so a long time.
Track was BIR in MN, probably have 1000 laps on that track before it happened on Saturday.
Past modifications:Modifications the day before Ice Mode on trackModifications right before Ice Mode got meI don't believe ANY of the mods above were performing different than designed and expected, so don't interpret any of them to be at fault.
As an engineer who has lead vehicle teams doing software controllers, I believe this combination send the ABS and Stability Management controller (from 2005!) to a very bad place.
From what I did to turn off and on, it was the aggressive initial bite from the Hawk pads that finally triggered this, along with all the mods that were already there. I could avoid it by braking early and lightly, even with those pads.
I changed back to Pagid Yellow pads and could not get it to happen again. Those pads don't have an aggressive initial bite.

I learned in the paddock that Spec Cayman drivers do two additional things to avoid this.I have not tried these and i am not "recommending" these mods, just relaying some information for your entertainment.

Hopefully, someone can learn from this and avoid finding Ice Mode on the track or at least how to manage it.

Steve

 

Any chance you logged data on canbus during this?

My friend (very fast and aggressive driver) borrowed my car (981 Cayman S, x73, Ferodo DS1 pads, RE71Rs) for a session and experienced ice mode that had him clip a tire wall. It was about his 5th lap and he said in the braking zone he only had about 85% brakes when he needed 95%. I was logging the canbus at the time and while his rate of braking was consistent, he was applying more pressure during the ice mode time. Comparing with my data, he brakes my more aggressively. I'm used to driving E36s that also have ice mode so i tend to consciously squeeze on the brakes. I also like to brake less and trail it out more. I've had it a few time in the E36 and did a release/reapply and that fixes it at the expense of chewing up some time/distance.

The event prior, another guy i know in the club crashed his 981 pretty hard into a tire wall and claimed ice mode was at fault.

Pretty scary, but be prepared and maybe even practice pumping the brakes if need be. Also squeeze brakes on smoothly, especially in bumpy braking zones. I normally chirp ABS, but not more than a pulse.

Do you know that PSM has anything to do with it? I tend to leave PSM on all the time, but my buddy who had it with my car had it off. The other guy i know had it off as well.

 

Yes to both of those and every SPC'er I know has done this. Like you, I am not recommending either of these mods, but I have not had ice pedal since doing them. I was also just at BIR for the club race with no issues (well other than a broken windshield - that track is dirty ). I have tried other pads but I always come back to the Pagid Yellows - 29's front, 19's rear. You do want a little extra bite in the front. Cold tires can also play a part with inducing ice pedal especially in combination with a bumpy brake zone.

As for brake application, I am not sure what was meant by squeeze. If you are slowly applying the brakes then I would not recommend this. What I and the SPC'ers have discussed, is an initial low pressure application then an immediate high application application followed by trailing off. It is kind of like you set the brakes, then mash them.

I would also recommend as much cooling as you can get to the brakes.

 

No, sorry was not logging the canbus when this happened.
For Ice Mode, I did not experience anything close to 85% brakes. At first I told people i had "none", but thinking back I had a small amount so 25% seems right.
People do report if you get on the brakes easy at first you can avoid this mode.
According to people that have solved this, yes PSM software is the cause of this mode of ABS. I always run with PSM set to "off", but is it never really fully off. Car is in the shop right now getting disconnect added to yaw sensor ground. This will create a PSM error and should COMPLETELY turn off PSM. According to those that have done it, there is no more Ice Mode possible with yaw sensor disconnected. But, there is no sleeping PSM to save you ether, so they install a toggle in case they race in the rain. I would not advise anyone do this for a street car! This is only reasonable to me for a car you have dedicated to the track or racing.

For a street/DE car, I think just back off the aggressive pads, brake easy into corners, and don't use slicks.

 

Thanks for the post. Hope you did well in the race. Glad I did did not wad it up in turn 3 that morning, it would have delayed things.
Auto Edge has the car now and is doing the yaw sensor disconnect switch at the ABS reprogram to ceramic brakes.
I do have GT3 brake ducts, but rotors were near the wear limit so replacing those for cooling and smoother braking.
It turned out I actually had Pagid Black RS14 in front and Pagid Yellow RSL29 in back. Forgot that last time I replaced, I could not get RSL29 for the front. i will try this setup with the new mods, as it should provide some front bias. Did not have Ice Mode with this setup for pads, only happened with Hawk DTC-60/DTC-30 pads in there.

If I get to the track in Fall, I plan to switch cars with a local SPC driver to give it a try. i am thinking of building one for next year!

 

I'd documented this a lot in the past when heavily tracking my 997RS. Rock hard pedal, very light braking. First time scared, now I can control and avoid it. Only ran off track once. Luckily, in a braking runoff area.
Trigger: Overly aggressive braking into corner when braking zone or track surface upsets car (ie bumpy, lots of rubber, etc).
The save: get out of the brakes and quickly back into them
Key: start braking action slightly earlier, ease (quickly) into brakes, don't 'stab' them
In the data: my car doesn't have pressure on the data, but I do have G, wheels speed, brake action, etc. you can see the effect, brake action and like .3g braking force when it occurs, usually with a very brief lockup of one front wheel.
Also, I found when I ran sprint type pads it was worse, I settled on endurance type with a slightly more aggressive rear compound.

 

I only know of one SPC'er that runs Hawk pads and he said he liked them, but I have no idea what compounds he is running. I have had success with Pagid and brake pads is not an area I like to leave to chance

Great to hear - is that Keith Fritz's car? We have a group email setup - probably 20-30 guys that either have an SPC or are thinking about it. I just put Dan Martinson on it. If you want me to add you, either now or in the future, just PM me your email address. We are very open with what we do and have done with our setups - everything from brakes, suspension setup, etc. It's one of the reasons I like the class.

As for cooling, in the front I run the Olsen ducts with air plumbed to the ducts through the frame rail and in the rear I have modified brake shrouds with air plumbed to them.

 

No, but I have talked to Keith Fritz about the SPC class and what class my 987.1 Boxster might be allowed to run in. Maybe Boxsters will be allowed in SPC, but I would need to upgrade the engine to a 3.4L Not not seem like a good path.
t was Tylar Twite that offered to swap cars in the fall.
I will send you a PM on the email SPC group, thanks!

 

Are you sure that ice mode is only possible with PSM active to some degree? I thought it was intrinsic to the Bosch ABS itself. For example E36s have ice mode and have no stability control at all.

 

The only thing I am really sure of is software engineers can mess up any controller. The particular Ice Mode in the 987.1 P-cars seems conclusively triggered by PSM. But, since that ABS controller actually commands the mode in the end, it’s possible it could do it on its own with some other combination of sensor failures or implausible signals. So, Ice Mode could still happen if PSM is disabled with the yaw sensor, but does not seem to happen on these cars if the system is working normally. Could certainly be different for other manufacturers.

 

This seams to be the most recent one on Ice mode so I will ask this here:

Does the abs or psm light in the cluster blink while ice mode is going on? I am trying to find if this is what is going on with my abs since I upgraded a bunch of part in the braking system and the abs is no longer the same.

 

Sorry, I can't remember what was shown on the dash. I was too busy trying to keep it on track.
It has never happened again since switching back to less aggressive Pagid Yellow RS29 pads and the reprogram for ceramic brakes.

 

I ran into this for the first time with my GTB1 Cayman this weekend. I'm running AP Racing front and rear brakes with Ferodo 3.12 pads and Nankang AR1s. I also already have the PSM disable switch. The only place it would happen somewhat consistently was at Road America at the Corvette Bridge Turn 6 braking zone. I think the car was getting light in the rear and I was hitting the brakes pretty quickly rather than a slight press to load up the front, then full hard for the maximum braking pressure. It also happened twice over two days going into corner 8.

Was AutoEdge's fix to disable the YAW sensor and ABS reprogram the confirmed fix? I'll have them do this in the spring.

 

It never happened again for me after switching back to less aggressive pads (to Pagid Yellow) and the ABS reprogram for ceramic brakes.
Auto Edge installed the Yaw sensor disconnect, but I did not use it. When I disconnected it, I got a PASM system warning. That did not make sense as there is a TPC Racing DSC controller in there for PASM with it's own sensors, but we never figured it out. Spec Cayman guys don't have that issue of course.
I have since moved that car back to street, partly for this issue and mostly because I missed shifting it on the road!

 

The proximate (and only) cause of ice mode, AFAIK, is that all 4 wheels become locked up simultaneously for an instant.

3 wheels (or fewer) can lock = no ice mode.

Ice-mode is a "feature" of all ABS systems based on how ABS works. (A reading of the Bosch manual will confirm this.) At least one wheel must be turning as a speed reference. If all 4 lock there is no reference and the system will withdraw most, but not all, hydraulic pressure. As some have said, it leaves about 25%.

Normally when a wheel locks the system will release the pressure just to that wheel, allowing it to turn again. If all 4 lock the system cannot reset without the driver releasing the brakes to allow the wheels to start turning again.

Any driver action that prevents all 4 from locking simultaneously, such as a smoother application of the brakes, especially in bumpy conditions, can prevent ice-mode. Anything that changes the stock system parameters (pads, suspension, grippier tires, stability control interference, etc.) can make ice-mode more prevalent. If you have a really fast foot you can make many completely stock cars go into ice-mode even on a dry surface. No one knows how many people have been killed because of it. The driver will always be blamed.