Does your car have disc brakes? Chances are if it is a fairly new car it does. However if it’s very old it might not. Do you know why car manufactures changed from drum brakes to disc brakes? The answer is safety. Disc brakes stop faster and have less fade than the older style of drum brakes. Let’s look at why.
A drum brake looks like a flat plate with a large lip. The drum pads sit inside the drum brake and press against the lip. The way a brake works is to change kinetic energy from the motion of the car into heat through the friction of the brake pad rubbing against the lip of the drum brake. Because of the way the drum brake is packaged, there is little room for the heat build up to escape. With the lack of cooling the brake pad overheats and starts to lose some of its ability to cause friction with the drum. This is called brake fading and when a brake starts to fail, you cannot stop as fast.
A second problem with drum brakes was when they became wet. The water made the pad and drum again lose the ability to create a lot of friction. And as we know, less friction means less stopping ability.
Disc brakes were first used on racing cars. A car with disc brakes could go further into a corner before braking than a race car with drum brakes. This allowed the disc brake car to enter the corner faster, and exit faster which gave it a lead in the race. The reason the disc brakes worked better is based on their design. Instead of a lip on a drum brake the pads on a disc brake system rub against the disc or rotor. This rotor is exposed to the air and can bleed off heat much faster than a drum. Since it can get rid of heat faster it is more resistant to brake fade and therefore can stop a car faster.
In addition to its advantage in not fading as fast, the disc brake also resists the problem with water. Since the rotor is exposed a light press of the pads against the rotor will get rid of most of the water. Again this helps the disc brake system stop faster in the wet than a corresponding drum brake system.
Most of the muscle cars of the 1960’s and early 1970’s were drum brake equipped. While the owners want to keep the cars as original as possible, they really had too much power for their braking capability. So you will find a lot of these cars which have been upgraded to disc brakes. It’s not a hard upgrade to do, but since it involves a critical safety component of a car, it should be left to a brake professional mechanic to do.
