Drum vs. Disc brakes?

[ragingfish]

What are the differences in drum and disc brakes? I mean, I know disc uses brake pads and shoes and squeezes the rotors to slow the car down...how exactly do drum brakes work? What are the pros/cons of each type of brake, and why does base have mixed brakes while GT has all disc? Thanks!

[esjones]

In a drum brake system, the wheel is attached to a brake drum. For a mental picture, cut a soup can with a cut parallel to the end, about 3/4 inch from the end. If this were a brake drum, the wheel would attach to the flat end of the can (on the outside), and there would be curved pads (the brake shoes) attached to a stationary backing plate very near, but not touching, the inside surface of the can. The drum and wheel rotate freely on the axle as long as the brake shoes are in this position. When the brake is applied, hydraulic fluid in a brake cylinder applies pressure to force the brake shoes outward, rubbing against the inner surface of the can/drum. This friction stops the drum and wheel, which stops the car.I believe that the advantage that disc brakes offer over drums is better stopping power, less affected by heat buildup from heavy or repeated braking, largely self-adjusting and fewer parts. They're also more expensive, which is why you find them on higher-priced cars, or as part of performance option packages, like the GT.

[NovaResource]

Actually, drum brakes have greater stopping power because they are "self-energizing" and usually have more friction material area. Drum brakes have less rolling resistance and they are lighter. However, drum brakes don't dissipate heat very well. Discs work better because they can get rid of heat faster and are less prone to fade.

[ragingfish]

makes sense! thanks everyone!

[NovaResource]

Yes. The front brakes do approx 70% of the braking. This is also why rear drums are still around. They are lighter and cheaper (for the manufacturer) and since they only do approx 30% of the work, heat isn't a major problem.