wookie@alice.UUCP (08/19/83)
I guess this braking question must depend on the situation in which you find yourself. The coefficient of friction between the tire and the road increases as the tire begins to slip (maximum adhesion) and then drops of dramatically as the tire begins to slide. This is much the same in turning a corner. The trick is to be able to sense when you are at the limit as this is the best point on the curve for maximum traction for starting, turning, and stopping. In racing I try to do my maximum braking effort just before going into a turn. Thus the tires only job at that point is to slow the car. I will take the brakes to where I feel the tires beginning to slide and hold that point. If I am starting into the turn I will have to ease off the brakes as I am now asking the tires to produce the sideforce needed to turn the car. Thus if I stay on the brakes at the limit when I start to turn the front will loose adhesion and the car will go straight into the corner. The problem here is that I have had practice and the car is set up for racing with balanced braking systems and the weight of the car never changes except for fuel load (and if I have been eating too well!) The brakes are therefore always predictable and all four wheels will begin to slip at about the same point (The front I hope will slip first!) The same techniques apply to everyday driving. Maximum braking occurrs just as the tires are beginning to slip. Unfortunately the average car does not have properly balanced brakes and the loads are widely variant. Given the average driver the question must be asked what is it you want to do in a given situation. If you lock up all four wheels then you will stop in almost a short a distance but it will be in a straight line (the direction the car was last going) and you will have no directional control at all. This is the lock em up and ride it out approach. With proper breaking you can trade off stopping and directional control to help get avoid the accident. This of course requires practice and a bit of skill. In racing I might for example lock up all four wheels if I am spinning because of taking a corner too fast. As I see the direction I want to go coming up I will then let off the brakes and apply power to get the car going in the proper direction. This really takes a lot of practice and precise timing since if you let off the brakes at the wrong time the car may come out of the spin while pointed at the side of the road! This is very hard to explain without you experiencing it! Anyway what I think this all means is locking up the wheels may be best for the inexperienced but knowing how to control the situation is far better in the overall picture. One other thought is that most people don't even know the handling capabilities of their cars and it may be that manuvering around the problem is much better than hitting the brakes at all! I have had a couple of situations where had I slowed or stopped the results would have been a major accident but turned out OK by maintaining speed and avoiding the mess. There is a lot to think about in those split seconds and I'm glad I have had a little racing experience to help on the highway. I've done things on the race course I hope never have to be done on the street! Keith Bauer White Tiger Racing
laura@utcsstat.UUCP (Laura Creighton) (08/20/83)
talk to the folks that run driving schools. A lot of them teach "lock on the brakes" indiscriminately. They preach that you cannot learn to steer well enough to get out of an accident. They also want you to lock you brakes when you skid on ice. I think they are WRONG WRONG WRONG. I *know* how to steer a car. My depth perception is pretty lousy, though, for I am blind in one eye. If you lock your brakes you are committed to stopping at a certain distance away in a straight line, and that distance is dependant on your momentum (and how good your brakes are, naturally). if I guess wrong, i will end up in the rear of the car in front. I would much rather steer into another lane. The question is, is braking a good thing to teach? If most people who are driving are never going to learn how to steer their car (or how to react in an emergency) is giving them a simple instruction that does not require thinking more important than giving them good advice? laura creighton utzoo!utcsstat!laura
wally@cornell.UUCP (Walter C. Dietrich) (08/22/83)
YOU may only need to make a few "panic" stops in your lifetime but that isn't true of everyone on this net. Here in Ithaca just getting the car to stop going down an ice-covered hill is enough to cause panic. You may wonder why I drive on ice-covered hills but sometimes we don't have a choice here. I pump the brakes in those situations, it seems to work best.