Ice mode solution?

wstar

Well, yesterday I finally had a hard ice mode condition on the track. It was a pretty scary experience. Now that I know for sure that this was ice mode and exactly what ice mode feels like, I know I've hit it before a little, too, just not as critically.

Luckily, this track I'm running at always has easy run-off on the braking zones (extra pavement, or at least grass). The setup was a long straight with a straight brake zone to scrub a little speed (~115 -> ~80), then maintenance throttle for a gradual sweeper to the left, then straighten up and a hard, short straight braking zone down to ~35-40-ish for a hard right. It was in that second braking zone that I hit it. I had been gradually raising my speed coming into there on each lap, and backing up my braking start. Then I nailed everything really great one lap going into there a bit faster than before, and the brakes just iced up. Hard firm pedal, ABS pulsing like crazy, and little to no braking force.

I wasn't really ready or expecting it, so I didn't even try to re-apply or modulate. I blew past my intended turn-in spot still going too fast for the turn, so I just held straight past it and then turned right a little for a bit of an angled slide, and eventually the brakes semi-fixed themselves and killed my speed just in time to bring the car to a stop at the brink of the pavement (and then I rolled it off the edge of the track to get out of the way and find a good time to re-enter).

It was the 3rd of 4 sessions, and I was able to avoid it on the 4th run by taking that spot a little "easier" and less aggressively. Going back out today on the same equipment, same track, so I came here to read back through all of this. Having done so, I think the trigger was that my initial pedal stab was a lot sharper than I normally do. Usually I'm pretty good about rolling into either pedal instead of stabbing them, but in this particular case I knew I was set up straight and perfect and had a lot of speed to scrub in a short distance, so I stabbed pretty hard.

I'm on half-decent street tires (Conti DW) and XP8 all around, stock calipers, RBF600 fluid, braided lines, and RA's 2-pc slotted rotors (which seem like they have a better-than-stock cooling vane setup), but no ducting for the fronts.

So for my sessions today, I think my focus for preventing a repeat will be (1) Don't initially stab too hard, and (2) if I feel it happening, try to re-apply / modulate repeatedly to kill it, and (3) Try to engine brake a little later (I normally downshift pretty much at the moment I'm getting on the brakes, when applicable).

In the longer term, I'm going to need to fix this up a little better though. I'm figuring bias is one of the key issues, but I don't think on these street tires it would be wise to go XP10 front, right? So that probably leaves me with downgrading the rear pads from XP8 to... I don't know. Something that can take the heat, but doesn't lock up as easy as XP8 rears do. Or do you think XP10+XP8 might fix it and not be too grabby for the tires?

That or try disabling ABS. I'm willing to learn to live without it, I hate it when it does engage. The simplistic "pull the ABS fuse in the center console" thing also kills your brake lights though, right? Is there a better way to disable it that I could put a dash switch on?

__________________
7AT Track Car!
Journal thread / Car setup details