NDBakken

Has anyone experienced, under very hard braking, that the pedal becomes beyond firm (almost like frozen) and the car loses braking force?

The only way I can describe the feel is like pads that went down to the metal. Plenty of firmness in the pedal, but the car does not slow down.

This has only happened to me on the track in race conditions. And it is intermittent.

Others have said it is ABS pulling brake force. But, I know what that feels like (from this car and others) and this does not feel the same.

When I have felt ABS in the past I felt a pulse, not like the pedal just froze or hit a wall. Also, the car still slowed down.

When I feel this phenomenon I really feel the car lose a lot of stopping power.

Spyerx

search "ice mode" Don't jab pedal, ease into it, the car is directing the brake force to rears as it thinks car is sliding. My guess is the track is slippery in those areas. If you ever feel this, simply ease up and get back into the pedal (fast) it will stop. You just need to be aware of the situation.

George from MD

Does anyone have a cure for this? I finally got my car on the track last year and experienced it a number of times. My cure was tapping the pedal lightly before I nailed it.

But having learned as a momentum type driver who loves late braking all my mates (my cars were never that powerful before) I think the problem is absolute BS and I can't believe someone hasn't come up with a cure. The brakes in my 993 were the hand of God...the brakes in the GT3 can be downright scary.

Drew_K

Yep, ice mode. I experienced it a few times when I first drove my GT3 on track. I was jabbing the brakes on cold tires, but now I know to load the front end just a little before really getting on the binders. I don't like the 'feature' either.

997s07

If, when, we put new coilovers in the car and disable the PASM, is ice mode still possible?

ABS and PASM don't play with each other do they?

Spyerx

Only full core is Motorsport abs. This issue affects not only gt3. COil overs will do nothing for this other than maybe better wheel control that may reduce effect. Has nothing to do with pasm

utkinpol

cure is to maintain proper ratio between front and rear tire diameters, close to stock.
then, as you initiate braking sequence develop a tendency to preload front first then quickly go full press into pedal. most usually ice mode initiates when car senses significant deviation of wheel rotation between axles. on a bumpy track it happens if your front is moving up on a bump and you stomp brake pedal at that time. or may be you used pads with very aggressive bite in front and not so much in rear, or other way around. if brakes are operated smoothly and pads are good it never happens.

ShakeNBake

I find that if I brake in full force after the weight has transferred to the front wheels, I never experience ice mode (unless there is an exceptional circumstance, like cresting a hill or transition). It takes a moment - so you can't just put your foot through the floor immediately when you want to start slowing down.

997s07

OK. Thanks.

dantzig

This phenomenon is a programmed in "feature" of the ABS in our cars. If you jab the brakes, i.e., apply then very hard, very fast, the ECU senses panic. The ABS is programmed to maintain 0.9g deceleration under that condition. This is the max available on street tires. Pressing harder on the brake pedal has no effect.

You can work around this as has been described above. Apply brakes progressively, rather than jabbing them. Once they are engaged, you can press harder on the pedal and get higher decelerations if you are on track tires that can provide it.

I got this info from Darick Dong, head of motorsports at PFC. I tried it at my next track event, and found that I was able to get 1.2 g under braking on Nitto NT01's, where I had been maxing out at 0.9 g before. Same tires, same track and conditions. Only my brake application technique changed. See friction circles below. Left: Jabbing brakes, Right: Easing into pedal

Jon

mjg

Great advice. If you can spare a couple of hours, there's a lot of great information in this brake seminar from Darrick Dong here:

audipwr1

Find braking on curbing will really upset it as well ie t10 and Sonoma

P.J.S.

As others have said, Motorsport abs ($10kish if I recall correctly) or drive "around" it using techniques described...

NAM VET

Dantzig, your pattern is a perfect shotgun choke for turkey hunting.

All the best...

dantzig

Maybe it's a Rohrschach test...