Brake drum systems are usually found on older vehicles. These systems have been mostly replaced by disc brake systems. Some vehicles are fitted with disc brakes on the front and drum brakes on the rear wheels.

The brake drum is located behind the rear road wheel on the side. The road wheel is attached to the drum with the wheel nuts or bolts. Inside the drum there are hydraulically operated brake shoes that are forced onto the smooth inside surface of the spinning drum. When the brakes are applied the friction between the brake shoes and the inside of the drum slows the rotation and subsequently the vehicle.

Problems requiring replacement of the brake drum are usually the consequence of worn down brake shoes which can cause excessive scoring of the smooth inside surface of the drum, resulting in poor braking performance.

Due to the high energy forces, heat, friction and stresses involved with the braking system in the area of the drums and wheels it is of the utmost importance that all components are in good order.