To add to the pool of knowledge on this thread -- I was at a race weekend 2 weekends ago with my car at Summit Point and the first session out, sure enough, Ice Mode going into T1 at 140 mph (I was taking it somewhat easy and feeling out the brakes). I was able to lift off a second (1/2 second?) and then get back on the brakes and bowl the turn without going off. When I got back on the brakes they felt normal.

I was running Pagid Greens all around (same as Blacks from what I understand but made for the Cup Car series). I switched to Pagid Yellows in the front after that and that made a HUGE HUGE difference with the braking. The fronts no longer went instantly into ABS and I was able to avoid Ice Mode for the rest of the weekend. I also was not braking 100% for the rest of the weekend and I don't think I'll do so until I get the Cup ABS in the car (waiting for the control unit from PMNA).

I think the lesson learned, and I'm adding this for anyone else with a similar setup so that they don't crash -- My testing has shown that the safest combination is probably to run the Pagid Yellow in the front, Black in the back.

 

Or Yellows all around. My Koni friends ran RS19's front, RS29 rear.....

 

Darren,

This is a really weird issue and has me baffled. I turn a mid 1:21 at Summit in my 996 (it is my home track) and never experience Ice Mode. My car doesn't have PASM or E-throttle. I have an early 1999 tub with 2003 engine and trans but with all of the 1999 electronics.

Going into T1 you should not be unweighting any wheel so that alone cannot be the issue.

When you say Ice-Mode are you referring to just early ABS activation or a situation where even with the ABS pulsing you are only getting minimum pressure to your calipers no matter how hard you push on the pedal?

 

I definitely think the problem is more pronounced in the later 996's, which use the Bosch 5.7 ABS vs the earlier cars like yours which has the Bosch 5.3 ABS.

Not to repeat the entire thread -- this is a race car with GT3 brakes and full slicks -- if you don't have big brakes and slicks then you're very unlikely to have the same issues.

 

Yes, while I don't have big brakes and slicks I am running 3 seconds a lap faster and without the issue. So the speed alone is not the issue.

If it were me I would simply try to defeat the PASM system which unfortunately turns off the ABS as well. And see how that goes.

Good luck,
-Paul

 

No speed is not the issue. As discussed the issue is that the big brakes and slicks are able to slow the wheels down (without losing traction) faster than the ABS system was designed for -- the system thinks you're on ice when this happens so it reduces the braking force to 25% or so to "help" you.

The car does not have PASM it has PSM, which is integral to the ABS system. You can't remove the PSM without changing the ABS controller, which is what I'm doing by installing the Cup Car ABS control module. I think the problem is more the programming of the Bosch 5.7 control module than the presence of PSM, though it hardly matters, the whole control module has to go.

 

Sorry, meant to say PSM. Bummer that you have to yank the whole thing. My suggestion was to disable power to the PSM/ABS controller. Then you would not have ABS but shouldn't have this problem either.

You can run w/o ABS in the dry and only use it in the wet. Just a thought.

 

That's a thought except that the ABS unit also has electronic bias control -- I very highly doubt that the default bias would be very effective on the track.

 

Paul, I don't think lap times are the issue. Darren is still developing the car which was faster before all the mods. The ABS issue is affecting his confidence in relying on the brakes for his driving style. If lap times correlated, then I should be having issues running a lower hp car (993NA) that ran 1:20.xx's during an actual race at SP. I suggested the Pagid Yellows at the track and it did help get the ABS system to not go awol every time he used the brakes heavily. Ultimately, his car will be super fast, it is the sorting period that sucks big time.

 

Also take into account the pad. Different pads will provide different friction coefficients and that has a huge effect on ABS performance. It is entirely plausible to make a very aggressive pad change only (A to B, stock to race) and have the issue occur. Generally the system will be robust to a pad change, but if you're making a very large jump in performance. Probably, Darren, why you saw such a large difference in switching from the Green to the Yellow.

 

This thead is of some concern. Hypothetically if you were building a race car now, what system of ABS would you employ. Obviously the high end Bosch units or something similar would be at the top end but not everyone can afford this level. So what do we use? This would be a custom setup so not necessarily bound to any specific model due to the car.

 

 

Not bad, but if it were me I'd start with this:

 

You beat me to it Larry -- here is the one I put in my Blue Acura:

 

It's been fixed a few ways, pick your poison and do it, they all are better and correct the "black ice" condition.