DIY Tips for Mechanical Drum Brakes

Mechanical drum brakes are a common alternative to disc brakes on many cars, trucks and SUVs. Drum brakes are typically found on the rear wheels, especially on older vehicles. They operate differently from disc brakes, but drivers can still inspect and even service drum brakes by following a few simple tips.

Removing the Drum

Removing the drum from the brake assembly can be one of the most difficult and frustrating parts of servicing drum brakes. To make this task easier, spray the bolt that secures the drum, along with the exposed lugs and any other exposed hardware, with a lubricant such as WD-40. Wait for the lubricant to dissolve some of the rust around the drum, making it easier to remove. Spraying the other hardware will make those pieces easier to remove as well when the time comes. If the drum is still stubborn, use a rubber mallet to break up the rusty seal all the way around the rim of the drum. This can also help loosen a drum that is rusted in place. Once the drum is off, you can clean it with a lubricant to remove rust and make it easier to replace at the end of the repair or to remove in the future.

Checking Shoes

Even if you arent planning to replace the drum brakes shoes, any time that the drum is off is a good time to inspect them. Check to ensure that the surfaces of both shoes inside each brake are smooth and clean. Some drum brake shoes come with warning strips that will show through when there is very little material left. Make sure that the indicator strip, or the rivets in the case of riveted shoes, doesnt show. Also check the inside of the drum for smoothness and warping, which can occur due to excessive heat and interfere with braking performance.

Disassembly

A drum brake includes many small springs and other parts, so disassemble the brake with care. If you dont have access to a service manual with clear photographs or diagrams of the brake assembly, you will want to create your own diagram. Indicate the order in which you remove the parts since reassembly will be done in the opposite sequence. To actually disassemble the brake, use vise grips to grasp the retainer springs. To loosen the brake lines, use a flare wrench rather than an open-end wrench.

Keeping Clean

Brake jobs are notoriously messy work. Gloves are the only real way to keep your hands clean, but they may hinder the precision work involved in servicing drum brakes. To keep your garage floor clean, place a pan beneath the brake. This will catch any rust or brake dust, along with brake fluid should you discover a leak in the brake line or a blown wheel cylinder. Take special care when handling brake fluid, which can easily damage auto paint.

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