Racing Schools Safety Fast: Antilock Braking

Antilock Braking

In my first braking article, earlier in this series, I promised a separate article on antilock braking systems (ABS). A recent report by the Insurance Institute for Highway Safety (IIHS) has raised questions about the effectiveness of antilock brakes and prompts me to follow up with this article.

Strictly speaking, antilock braking isn't a racing technique, since most race cars don't utilize antilock braking. There are two primary reasons for this: 1) It isn't entirely clear that antilock braking will reduce stopping distance for the skilled driver; and 2) Antilock brakes add system complexity, cost and weight to the race car, the disadvantages of which outweigh any possible advantages.

The IIHS report, issued December 10, 1996, notes that in single-vehicle accidents, cars with antilock brakes are as much as 44% more likely to produce fatalities than are cars without the antilock system. While the Institute declines to give a reason for this, it seems to me that the reason is simple and obvious. I don't believe that it indicates that antilock brakes are ineffective or dangerous in and of themselves. The problem is that stopping with antilock brakes, in an emergency situation, requires an entirely different braking technique than the one used with conventional brakes, and virtually no drivers have had or taken the opportunity to learn this new technique.

Different ABS systems work and react differently under extreme braking. While they all prevent the brakes from locking up, many of them generate pedal feedback -- pulses or bumps -- when they're working. They may seem to be pumping themselves; they may alternate between feeling firm and feeling soft; they may feel as though the pedal is going to the floor. The instinctive reaction for most drivers when they feel this strange brake pedal action is to reduce brake pressure, which deactivates the ABS, increases stopping distance and can actually cause a loss of control by upsetting the car's balance.

I said earlier that it isn't entirely clear that ABS will reduce stopping distance for the race car driver. It is very clear that it will reduce stopping distance for the everyday driver -- except perhaps in loose gravel or loose snow -- but that's not its primary purpose. The primary function of ABS is to enable the driver to steer the car while braking at maximum effectiveness. But steering in an emergency stop is itself a new technique. Abrupt or severe steering movements under these conditions will, again, unbalance the car and may cause a loss of control.

If you have a car with ABS you must learn to use it. ABS works and works well when you apply maximum braking pressure and HOLD it. DO NOT pump or ease off on ABS brakes in an emergency braking situation, no matter what they seem to be doing. If you steer while in an ABS stop, do it smoothly, but don't, under any circumstances, release or lighten your pressure on the brake pedal until your car is stopped completely. None of the above, by the way, applies to pickup trucks with rear ABS only, which should be driven as though they have no ABS at all.

It behooves every driver of an ABS-equipped car to unlearn his or her old braking habits and to learn the new ones that work with ABS. To do that, take your car to a safe location such as a completely empty and obstacle-free parking lot or a completely unoccupied street, preferably when the pavement is wet, and practice hard braking. Don't "slam" on your brakes, but press firmly, as hard as you can, with the force that would definitely lock up conventional brakes. Start at 15 - 20 mph and try to lock the brakes up while driving in a straight line. Your tires may screech or even skid or slide momentarily, but they should not lock up. If you can lock your brakes up, your ABS is not functioning properly. Stop your practice immediately and get your brakes checked and repaired.

No matter what the car or the brake pedal does in this practice, don't let up the braking pressure. Get used to what your ABS feels like when it's working; then do the same thing from 30 - 35 mph. At each speed, once you are comfortable with the feel of the car in a straight line, practice turning smoothly but positively while under maximum braking. Repeat this exercise several times, particularly at the higher speed, until you are completely comfortable with the way your car will react to a maximum braking situation and are confident that it won't surprise you.

ABS technology is expensive, and the more expensive the car the better the quality of the ABS system it is likely to have. There is a world of difference between, say, the ABS in a relatively low-cost Chevrolet and a top-of-the-line Mercedes. Both, however, require learning new driving habits.

Learn your car's ABS braking, what it feels like in your car and how it's different from what you have learned in the past. It is an exercise that can save your life in an emergency.