There are a few different things that can cause your brake (I assume pedal) to pulse or "bounce" when you are slowing from speed. The most common is that you have a brake rotor or drum that is warped or out of round. This can usually be corrected by having the rotors or drums turned. This is a process that shaves the unevenness out of the metal surface of the rotor or drum. HOWEVER, this process makes the rotor or drum less able to disapate heat and more apt to re-warp. There is a minimum thickness available for every rotor and drum which lets the machine shop know how much of the material can be cut off the rotor or drum before the part must be discarded and replaced with new. I have owned 69 cars, all different kinds and years and I have not ever turned a rotor or drum. I have always just replaced them if there was a warp. This problem is most often caused by dragging the brakes from high speeds slowing down gradually and causing the brakes to heat up and then sitting at a stop with your foot pressed firmly on the brake when they are really hot...Another common cause of the brake pedal pulse is that a tire or wheel rim is out of round or a tire tread is seperating, or tire underinflation.
Weight transfer. When a car brakes, its weight moves forward and causes the front brakes to do the majority of the work in stopping the car.
Front brakes have significantly more stopping power than rear brakes.
BRAKES
Larger brakes = shorter stopping distance.
Automatic Braking System. Prevents brakes from completely locking up in panic brake situations, or poor traction, such as icy roads. Causes brakes to "pulse" rather than lock up and skid.
Certainly, all four wheel brakes are used in normal stopping. However, the lions share of the stopping power is from the front brakes, yes.
What causes the throbbing called a pulse?
The front brakes on any vehicle do most of the stopping. When you apply the brakes the weight shifts to the front of the vehicle. For this reason the front brakes are needed more than the rear. Try stopping a vehicle with just the hand brake which applies only the rear brakes.
Front brakes provide about 70% of stopping force. Disc brakes have an advantage over drum brakes in that they can provide more stopping force without overheating (and thus loosing their stopping efficiency). I believe drum brake units are less costly to manufacture than disc brakes, so using them on the rear also saves manufacturing costs.
Apply the brakes hard and steer out of danger.
No. Your stopping distance will almost double.
In general they SHORTEN your stopping distance as they can apply more force to the breaks.