Motor-Stadt Region

ABS -Don't take it for a Spin!

by Len VanderJagt
LVJ911@worldnet.att.net

  The Constant Reader will recall a recent discussion of Weird Happenings due to ABS. Jim Heisick, a serious student of driving, sent me a number of articles about the characteristics, pros and cons, of ABS braking systems, which he has collected from various sources over the years. With thanks to Jim, I'll boil down the collective opinions and wisdom from that material.

  First, as many of us know, ABS makes for LONGER stopping distances on certain slick surfaces. For example, loose gravel, or snow. Instead of building up a wall of debris in front of the sliding tire, those wheels just keep on rolling.....and rolling. I really work hard to avoid getting into the ABS with my awd van in the snow, for that reason. Audi provides an ABS defeat switch. When does the Audi manual say to turn off the ABS? Yes, that's it!

  Now, as pointed out in a Road & Track article almost 6 years ago, in the vast majority of cases, ABS will stop you fastest. Why? Well, in part because the first thing that happens in most emergency situations requiring maximum breaking and avoidance is that you panic, at least somewhat. PCA driving schools can go a long way toward building the knowledge and discipline, not to mention repetitive practice, to respond correctly under sudden pressure, but I think that it is fair to say that most of us at least initially blow it. I have done it both ways, responding perfectly on the street, yet locking up following a mental lapse on the track, when I am theoretically operating with 'all systems go' in my head. My driver ed training has without any doubt saved me huge dollars and probable injury on a number of occasions.

  Our concern at this point and in this column, however, involves track realities. On the track, I am convinced that ABS is a Bad Thing. Never mind that it encourages Operator Sloth (you aren't driving, you're 'operating' your ABS when you just mash the brake pedal then turn in), what's worse is what the ABS system may do to you in a spin. As I had noted two months ago, the old adage is 'in a spin, both feet in.' Your car then basically travels along the vector described just prior to lock-up, typically spinning you to the inside of the turn, hopefully before you come to a Hard Place. With ABS, your tires do indeed slide, as you approach an attitude at right angles to your direction of travel, since by definition you have overwhelmed the tires' ability to maintain grip. The heat builds up quickly in the tire, further reducing grip, by as much as 30%. Then, as you slow down, and as the car moves toward an attitude increasingly in line with the direction of travel, which is not necessarily where you were originally trying to go anyway, your wheels start turning again. Off you go, in whatever direction the front tires are pointed. Hope you're not pointed at a wall or guardrail.

  I had seen this occur many times in front of me on the track, and was totally confused for the longest time. "Well, he's not gonna catch that.....ok, it's working out....oh no, he's rolling it into the wall just when he had it saved!" This was truly mind-boggling when the direction resumed was backwards, across the track. I was with a student in a Lexus SC400 who backed into the wall on the pit straight at Mid-Ohio when I was quite sure we would not get that far, and I now think we just rolled on in. Of course the loss of the Lexus may not be mourned, but hey!

  In putting this together, I realized that the legendary MotorStadt event of Commodore Swampdog's trip into the Waterford Hills swamp is my first sighting of this phenomenon. The driver of the moment, who shall remain nameless, produced a big lazy 90 degree spin not 20 feet in front of me and my student, sliding over the apex curbing and onto the steep and wet grass embankment. The 928 was almost stopped, when the wheels start rolling and the African Queen (named instantly) slipped beneath the waves. It was stunning and inexplicable, given the grimace on the unnamed novice driver's face which showed the strain of pushing the brake pedal right through the floor. I always found that event curious, but now it comes clear.

  As Rick Neale, BMW CCA and SCCA champion has termed it, the new rule must be "both feet in and steer like hell!" This is not a comforting idea, but you need to keep it in mind.

  If you aren't driving an Audi, you may want to consider pulling the ABS relay before you go out on the track, or before a banzai run to the 7-eleven in the snow. In any event, there is a need for careful thought and consideration here. Please let me hear from you (LVJ911@worldnet.att.net), and we will continue to explore this issue. Until then, "if you can't turn in - don't."