There are two fundamental types of brakes on cars: disc brakes and drum brakes. Most vehicles today use discs up front and either discs or drums in the rear. Knowing the difference explains what parts your vehicle needs and how it behaves.
How disc brakes work
A disc brake uses a caliper to squeeze flat brake pads against a spinning rotor from both sides - see how disc brakes work. Discs are exposed to air, so they shed heat well and resist fade, and they are easy to inspect and service. That is why every modern vehicle uses discs on the front, where most braking happens.
How drum brakes work
A drum brake uses curved brake shoes that push outward against the inside of a spinning drum. Drums are enclosed, simpler, and cheaper to build, and they make a natural, effective parking brake. Their downside is that they trap heat, so they can fade under hard, repeated use, and they are a bit more involved to service.
Pros and cons at a glance
- Disc: better cooling and fade resistance, easy to inspect, self-cleaning in the wet. Costs a little more.
- Drum: lower cost, good for a parking brake, fine for the light-duty rear of many cars. Traps heat, more steps to service.
Where each is used
Fronts are almost always disc, since they do 60 to 70 percent of the stopping. Rears vary: many modern cars use rear discs, while plenty of trucks and budget cars keep rear drums. See brake shoes vs brake pads to tell which you have. Whichever your vehicle uses, service brakes as an axle set - find the right pads or shoes for your vehicle, and add fresh hardware.