mp5 said:
I don't want to start a war or anything but abs on slick surfaces INCREASES stopping distances. It's function is to allow the driver to continue to steer to avoid an accident. On dry surfaces, abs usually does not activate until extremely low speeds and has little effect on stopping distances. If abs actually provided shorter braking distances, it would be used in racing. If you don't believe me read your owners manual which states that braking distances are increased on cars with abs, or do a search on the web regarding braking distances and abs.
ABS is used in some racing....
But you're right, the entire purpose of ABS in the first place was to maintain steering control.
Although as ABS improves, we are shortening stopping distances in certain situations. ABS nowadays does not lengthen many stopping distances. On ice, ABS does in fact decrease stopping distance.
It's all about friction (s***, thank you Dr. Marvelous for figuring that out). Our brakes will sieze and break (unlock) at a certain point, based upon the friction coefficient of the pads and the rotors. Similarly, Our tires will sieze and break with whatever the driving surface is at the time. Now, these coefficients are constant (excluding outside factors like temp changes), e.g. the friction coefficient of our brake pads at 120 degrees Fahrenheit is "n". "n" is a constant. Same for tires, rotors, etc.
Say you're driving on a wet road. You've got two equations running. YOu've got the interaction between brakes and rotors, and that between tires and the road. The first relationship nets the better stoppage (obviously). Once your wheels lock up, that first equation is out of the picture, it's just tires and road. And it's very easy to cross that like to where the tires break (cut loose) on a wet road, as we all know. The point of ABS is to minimize the situations where the tires break (meaning when the brakes dont lock, i.e. "Anti-Lock Brakes") and we're operating on that second set of numbers only.
The reason why ABS wont decrease stopping distances in most situations is because that coeffecient between the tires and whatever the road conditions are is a constant, which means that no matter what, given the set of variables for that equation (tires and road), the factors stay the same. ABS keeps the tires rolling so we can turn.
However, it must be noted that turning while braking does eat some momentum, as the car is being made to change direction, it takes force to move something from a straight line path (i.e. a body in motion while travel in a straight line until acted upon by another force)
