85Gold

I believe he had an unbalanced system and lock up. He didn't talk about it to much in the download session. Maybe he will read this post and chime in.

Peter

Carrera GT

Agreed. Not an ABS "grinding" ... just rock hard at the top of the pedal movement.

Terry L

Please. We understand your point but this is not just slamming the pedal.

NJ-GT

It has happened to me in the 996 GT3 and 997 GT3 RS both with PCCB, never in the Cayman, and until recently never in the Fiat. With the 996 GT3 on steel rotors, I don't recall to have experienced it.

I had it for the first time at Turn 10 at Sebring last month in the Fiat. The nice folks from TuneRS in Coral Springs, FL found out my CCB rotors holes were clogged (I was using the stock pads). The guys cleaned the holes with pressurized air, and never experienced it anymore on the weekend. Before this track day, I never experienced the ICE mode in the Fiat, but a co-driver of mine had it at an autocross, we were both driving the same day and the same car, so something must be related to the braking style.

The worse car was the 997 GT3 RS, I had it at every track day, running MPSC 265/345, or Michelin slicks, or Hoosier A6.

All my cars use Castrol SRF or motul rbf600, track pads for track days, and street pads for street and autoX.

The feeling is very easy to describe, rock hard brake pedal and barely any stopping power, pumping the brake pedal helps, but it should be done progressively and without full pressure, not easy to do when driving at 8/10th or faster.

Nizer

NJ-GT: Which holes exactly are you referencing? Cross-drilled holes or the radial venting? If cross-drilled how does that jibe with using non-drilled, slotted rotors? Thanks.

NJ-GT

cross-drilled holes clogged with brake pad material. No idea why these cars get on ice mode, but it is not related to tires diameters or compound, because my RS had it with all sort of tire sizes and compounds.

The Fiat has been bulletproof on that ice mode thing, except day 2 at Sebring last month and I suspect it was related to using the stock brake pads, as they cannot tolerate the Sebring braking scenarios, plus the clogged venting holes, and obviously my driving.

Nizer

So if the theory is that clogged cross-drilled holes can cause ABS "ice mode" malfunction, wouldn't that imply that ABS wouldn't function one swapped to non-drilled rotors?

NJ-GT

no theory, my GT3 RS without clogged holes went on ice mode quite often on track days. The C5 and C5 Z06 go on ice mode as well, and they don't use cross drilled rotors.

This has to do with the ABS interpreting a slick surface (hence the ice mode), under track driving conditions. It's quite common when braking on bumpy sections of the track from high speeds, also when hitting the brake pedal abruptly.

Porsche MotorSports made changes to the 2010 GT3 RS ABS module that they ran last year at the Nurburgring 24hr Race, but no car manufacturer wants to talk about the real problem. I think they cover their butts by voiding warranties with track use, or not endorsing track use with their cars.

In the Fiat, the ice mode was invisible for almost 2 years. No matter how hard I hit the brakes in the Fiat, I can't get it to activate the ABS, I like the ABS in this car. I can flat spot my inside front tire entering a turn while on the brakes, it is a non-intrusive ABS. In my one and only ice mode experience with the Fiat, I blame the overheated stock pads and their inconsistent (on/off) friction behavior when overheated, so I can blame myself.

Nizer

Got it - just wanted to make sure I was clear that the clogged-hole theory was debunked. Thanks.

911rox

It seems to me that the thing most likely to trigger ABS mode is that rate of lock up (or how quickly ABS) kicks in. On ice, a sudden, sharp press of the the brake would likely lock the wheels quickly and trigger the ABS module into ice mode. The difference is that you are not likely to be doing high speeds in ice conditions on the streets.

Maybe they should get around this by:
a) having an ice mode defeat mode for track use. or
b) have a threshold speed beyond which ice mode does not trigger e.g. No ice mode if braking abruptly beyond say 70-80mph...

Obviously, porsche and other manufacturers would need to acknowledge the condition before they can address it and they obviously know about it if they modified their Gt3 RS for the 24hr NBR race...

Crazy Canuck

or have it hooked into the outdoor temp sensor. >8C or so not likely much ice around

911rox

Exactly!...

Todd B

If you do a search for ice mode, you'll find lots of cars suffer from this. I wonder how much of the ABS system is Porsche programed. I would think Porsche has only provided the parameters to an off the self supplier of a system, they do the programming and you end up with a one size fits all type system. One would have thought if you can turn off traction control and psm, then you should be able to change the ABS system to an off road mode.

Crazy Canuck

I thought TC, PSM etc. was never truly off. Sure it could be disabled but once ABS was triggered everything turned back on.

911rox

This is true for all Porsches except the GT cars... When TC and PSM are off, they remain off even if ABS is activated...