Do anti-lock brakes take longer to kick in?

Dear Car Talk

Dear Car Talk | Oct 01, 1989

Dear Tom and Ray:

I understand that anti-lock brakes work by pulsing the brakes to keep them from locking. My question is are there circumstances under which this could cause the car to take longer to stop? For instance, let's say you just start up from a red light and you're traveling 5 MPH. A child runs into the road to chase a ball. Would the pulsing of the anti-lock brakes lengthen the time it takes to stop the car?

TOM: No. Anti-lock brake systems (ABS) operate just like normal brakes under most circumstances. They would not pulse unless a skid was imminent. So at 5 MPH in dry weather, the car would simply stop as it normally does.

RAY: Anti-lock brake systems have electronic sensors that can tell when a wheel is just about to lock up. Before lockup occurs, the ABS releases the brake for a fraction of a second and then reapplies it. This prevents the car from skidding and brings the car to a halt as quickly and as nearly straight as possible.

TOM: Many people have the mistaken notion that it takes a shorter time for a car to skid to a stop than it does to stop without skidding. This is not true. Of course, if you want to SOUND like you're stopping as fast as you can, then it's important to have the screeching tires, the skidding, the fish-tailing and the black skid marks on the road. But even at a moderately low speeds, the best stopping occurs when you have point for point contact with the road. That's what you get with anti lock brakes under all driving conditions. They should be mandatory on all cars.

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