How do Rear Drum Brakes Work

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There are two styles of brakes common on most vehicles—disc brakes and drum brakes, which we had shown here. Drum brakes are being replaced more and more frequently with discs, but it's still not uncommon to find them in the rear of vehicles.

Drum brakes are a much more simple system than they look. You have two shoes with the friction material, a hydraulic wheel cylinder, retaining springs, pins, e-brake spreader, and a backing plate holding everything together. The retaining pins and clips secure the shoes to the backing plate. The retaining springs keep them centered and returning to their proper position when not in use.

When you push down on your brake pedal, hydraulic pressure is created, and spreads the pistons of the wheel cylinder, forcing the shoe out and into the inside of the drum, creating friction and slowing the rotation of the wheels. As the friction material on the outside of the shoes wears down with use, the travel between the shoe and the drum increases, meaning it takes longer between you hitting the pedal and your brakes engaging.

To combat this, we have what's called an adjuster. The adjuster, as friction material wears out, spins and spreads the pads, so they sit closer to the drum to compensate for the lack of friction material. This spreader arm is connected to your parking break lever or pedal by this cable.

When you engage the parking brake, this cable is pulled in, pulling the spreader arm, which as a pivot point above our adjuster bar. It pushes the front shoe out and into the drum, allowing the rear wheels to remain stationary. As you can see, we've replaced all of our brake parts here. We have some new retainer springs and a new set of shoes, tend to reuse the adjusters and the adjuster hardware, have a lot of thick full friction material there, going to give us some great stopping power, nice longevity out of this parts.

As with any friction surface or wear item, you can see the inside edges of our old drum have been worn down and have a little bit of heat mark. You can see the steel has turned to a blueish purple color. There's some pitting from the age.

New part has a nice clean smooth surface, going to make a really good contact between that shoe and the drum, give you all the stopping power you want to have on the road. See a wheel turning, you apply the brakes, friction stops it from moving.

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