It's been an issue...with not just Porsche but other brands ABS systems too especially when super sticky tires, agressive pads and modded suspension.

Just keep in mind with the mod game....everything works together as a complete system...tires, brakes, suspension....and the street cars ABS and PSM since they are tied together are designed really for the street.

 

That's my understanding too. ABS assumes a certain type of tire/grip, weight, brake characteristics and suspension. When those change the ABS control loop is changed and ABS becomes unstable.

 

Is less likely to happen on a car that doesn't have PSM?

 

For those driving VIR N course you'll experience ice mode every lap if you brake late on the top side where the N crosses the full (just before the right hand turn heading toward the roller coaster). Lots of bumps there and it's ridiculous you basically can't brake late w/o missing the apex.

If someone was really trying to go deep there I could see a big problem so don't brake late on a bumpy track EVER, no doubt the car can do it but the ABS system can't.

 

The big problem is that it does it in a bone stock car. My bone stock 700 street mile driven 997.1 GT3RS on N spec pilot sport cups went into ice mode into turn 2 at Hallett ( moderately bumpy hard brake from ~120 to ~30mph). Car was in as delivered condition.

 

If you read all the pages of this tread, there are many 'ice-mode' type situations. The bumpy brake zone mini ice-mode issue can easily be replicated 100% of the time with a totally stock car in as delivered spec. While extremely annoying and you would think easily fixable with a 'track setting' to at minimum reduce this annoyance, real Ice-Mode, as defined by this Thread as an instant high and hard brake pedal with virtually no braking power. The causes of this ice-mode scenario bare many common traits with the bumpy brake zone example such as:
- tires get unloaded in 'some' manner and the ABS computer reduces brake pressure with range being [Some, A Lot]
- the unload scenarios seem to be (bumps, change in slope of brake zone)
- a 3rd type of unload situation that can also compound the above is a too-quick brake pedal stab that insta unloads the rears because not enough time has been allowed to let forward weight transfer happen - if you also happened to do this brake pedal stab as you were at a point in the track where you hit a bump or the track braking zone goes slightly downhill you can basically guarantee of full ice-mode no brake moment - I believe this is what has happened to a few very unlucky people
- you don't even have to add in 1.6G Hoosiers to the situation but if you do, and then add possibly a very slight front rear circumference ABS mismatch from spec, and you manage to do all of the above wrong + this, then your chances of 5% braking when you asked for 100% grows exponentially.

Squeeze the brake pedal - don't stab it.
Avoid the initial brake application moment to be on top of a bump.
Avoid the initial brake application moment at a point in the track where the slope changes significantly downhill from what was flat (ie the weight over the rear tires changes)

Sometimes bumpy brake zones are unavoidable
- try braking offline
- try braking further offline
- brake early to scrub speed and then just deal with 50% brake pressure the ABS gives you
- it you happen to get it really wrong and get the virtually no brake moment with hard pedal, get off pedal entirely for 1/2 second and then re-engage with a Squeeze

This fully disengage then re-engage strategy works - but you really need to know the corners where it may happen so you are ready for it and have calculated your line/strategy when it happens.

Knowing all of the above allows one to live with the issue and work around it and basically make it a non issue from a True Ice Mode perspective. The bumpy brake zone ****ty 1/2 ice mode situation is just poor programming in my opinion.

 

I just stopped tracking the car and sold it shortly there after. I only had to have one rock hard pedal / no slowing moment to lose all enthusiasm for the car.
I am used to braking very late and very hard in open wheeled cars. That combined with a bumpy, downhill, very hard braking zone made for excitement. There is some runoff at Hallett's turn 2, but it terminates in fairly dense forest. Not a recipe for happiness.

 

4.0 ABS Hydraulic unit/ECU: 997.355.955.98

$3200-3400 List. Approx 2-3 hours install labor including bleeding the system.

New ABS programming that has fixed the Ice Mode/Slicks issue. It is not possible to flash/reprogram the ABS via PIWIS or other means. This is the next mod I will be doing on my GT3RS.

 

Interesting pos! Thanks savy

I've never been able to create Ice mode, but we all can use better ABS.
Do we know what the difference is? It's spendy, so I wonder if it would do anything for me..

 

Thanks Savy! Pity they can't make this a warranty-covered item. If PAG wants to charge us through the nose for 4.0 vanity bling so be it--I think that's fair game. But working brakes? Safety shouldn't be something we have to pay extra for!

 

Pete I'm sceptical.. Slicks? / fix the "problem"?

More info please. : )

 

I'm with you. I smell the smell of blown smoke.

If this were true, then there are a whole load of racers who have wasted '000s on more expensive equipment and programming.

This might work with a cautious driver who doesn't get the most out of slicks, otherwise....


R+C

 

Proof is in the pudding, I agree. However I do know the 4.0 ABS programming is changed to better deal with slicks (doesn't get confused).

Perfect in all situations? Not claimed. Better than 3.8, claimed.

Up to each individual to determine if it is worth investing in.

 

Since u getting 4.0 why don't u swap units and see what happens? If it doesn't work just swap it back. If works just buy another unit. Mike

 

It is a good idea Mike. But I have never had the Ice Brake on Corsa Systems, MPSC or Trofeos, so not the best person to test. Also- I have the 396mm x 362mm oversized MovIt replacement rotors on my 3RS, same as CarreraGT does and he tells me they eliminated the Ice Brake on parts of Laguna Seca where he was always able to invoke it on his Hoosiers.

Best person to test would be one with OE brakes and a track where they can provoke IB at will.