Common Drum Brake Problems
Drum brakes function by transforming the energy from the engine (in the form of hydraulic pressure) into friction, generating an enormous amount of heat in the process. Consequently, if the outer brake drum is cooled rapidly after heavy use, usually by being exposed to water, warping can occur. Warping can cause a shudder or pulse when the brakes are applied.
Another common problem with drum brakes occurs when the protective coating on the brake shoes wears off. When the brake fluid is released, the brake shoes are pushed outward against the brake drum and the wheels are slowed. Over time, however, the brake shoes become worn down and will need to be replaced.
Drum brakes rely on the hydraulic pressure from compressing brake fluid to generate enough friction to stop a vehicle. If the hydraulic wheel cylinder is leaking, however, fluid will be released into the brake shoes and drum. Consequently, the two forces that are responsible for stopping the car will be compromised—pressure and friction. The wheel cylinder won’t be able to create enough hydraulic pressure to push the brake shoes outward and the brakes shoes will not be able to generate any friction if they’re oily.