| Field | Automotive maintenance |
| Went Obsolete | 1970s |
| Made Obsolete By | Self-adjusting drum brakes, disc brakes |
| Knowledge Assumed | Basic mechanical skills |
| When useful | Working on older cars with stock drum brake systems, performing brake jobs on some newer cars with rear drum brakes |
Drum brakes were standard on most cars until the late 1960s and early 1970s when disc brakes became more popular because of their increased stopping power. Drum brakes function by a hydraulic wheel cylinder pushing an abrasive drum shoe outward into contact with a brake drum, causing friction and deceleration. After a few thousand miles the shoes will begin to wear and require adjustment so they make full contact with the brake drum and produce maximum stopping power.
The standard method of adjusting drum brakes requires raising the front or rear tires off the ground (whichever end or side is to be adjusted). A brake drum adjusting tool or a long screwdriver are also required. With the selected wheel in the air, locate the adjusting access hole in the rear of the backing plate (often covered by a rubber plug). Inside is a “star” adjuster that can be turned clockwise or counter-clockwise with your adjusting tool in order to move the brake shoe closer or further away from the brake drum. Proper adjustments vary but a good rule of thumb is to adjust the shoe until it drags ever-so-slightly. It is important to adjust both sides of the car equally so the brakes don't pull to one side.
Many cars and trucks are still equipped with self-adjusting rear brake drums which are often never replaced. However, sometimes a mechanic will need to adjust the rear brake drums “all the way in” in order to remove the drum. After replacing the shoes and hardware, the mechanic only needs to adjust the brakes close and the self-adjusters will do the rest.