From Behind the Wheel by Dan Croteau
Winter has arrived with a vengeance these past few days. In fact twenty-four inches of it landed in my neck of the woods over the past two days. Going out over the weekend it still amazed me to see quite a few cars, trucks and SUVs firmly implanted in a snow bank or buried in a ditch. Having grown up in New England as many of our members have, I always need to remind myself about the joys of winter driving and how it affords us the opportunity to become better drivers on the track. Over the next few issues of Winners Circle I'll discuss various aspect of winter driving directly applicable to track driving. Let’s start with braking since this is a skill that usually generates a lot of misunderstanding and hence provides a lot of room for improvement.
With the popularity of 4-wheel drive, moving forward and accelerating can be accomplished without much difficulty. But 4-wheel drive does nothing when it comes to braking and slowing down. Keep this in mind also if you have an all-wheel drive vehicle. It's very easy to pick up a head of steam only to find that you're about to make an un-friendly introduction to the rear bumper of the poor guy at the stop light in front of you.
When you first go out in poor conditions get an idea for how your vehicle is going to behave under braking. Travel very slowly, about 10-15 mph, along the middle of a deserted stretch of road or on a large open parking lot with plenty of room and no cars in sight and then hit the brakes hard. If your car is equipped with ABS you'll feel the pedal pulsate as the ABS attempts to keep you tires from sliding and bring you to a stop. If you don't have ABS your tires will lock up and you slide to a stop.
Hopefully you've stayed in a fairly straight line while doing this, but this may not always be the case. Most roads are crowned with a concave surface; higher in the middle and lower on the sides to facilitate drainage. So, if the road is crowned your car may veer slightly to the right as it "falls of the road". Also, if your car has some brake bias it may pull to the right or left. Pay attention to the distance it took you to stop and whether your car stayed straight or veered to one side. In addition to being aware of you cars behavior as you brake you'll also know for certain if you have ABS and what it feels like.
ABS can be a wonderful thing since it prevents the tires from locking up and retains the ability for you to steer the car. But braking with ABS is actually less effective than threshold braking. Threshold braking is braking with enough force applied to the pedal to the point where the tires are just on the verge of locking up or ABS becoming active but are not. On the track or on a snowy road you can actually stop quicker if you avoid going into ABS all together by modulating the pressure on you brake pedal.
The factor which comes into play is weight transfer. How you apply the brakes has a tremendous impact on your overall ability to stop. The more weight that a given tire has on it the better it grips. In braking, the process of de-accelerating shifts weight onto the front tires which perform about 80% of the work when braking which is a good thing. If you're driving down the road and just slam the brakes on, little or no weight transfer has occurred at that instant in time, and there is a good chance that you'll shock the tires into lock up or ABS. If instead you apply increased pressure onto the pedal gradually by squeezing the pedal with your foot you'll allow the weight to transfer. It may sound like a contradiction when you’re trying to stop in a hurry, but we’re not talking about this occurring over minutes. With practice this can be accomplished in fractions of a second.
Keep increasing the pressure until you feel the ABS come on or the tires lock. Now ease the pressure on the brake back off just a bit and you'll be at or pretty close to maximum brake capacity. If done right you tires will be just about locking up but still rolling without ABS coming on. When you are trying this braking method keep the heel of you right foot on the floor and apply pedal pressure using your foot not your whole leg and you'll be able to modulate pedal pressure more effectively. It will feel like trying to step on an egg without cracking it! It's not easy to do and definitely takes some practice. Stay on the deserted road or parking lot and try this a few time whenever you have the opportunity. Keep these things in mind and your ability to slow or stop on a snow covered road or at the end of the straight at Valley Motor Sports Park will be sure to improve.
Yours truly from Behind the Wheel,