Haynes Tech Tips - Brake Shoes
Since most vehicles with drum brakes have them on the rear wheels only, the brake lining material wears at a slower rate than do the linings on the front brakes. They will eventually wear out, though, and it's important to periodically check them (every 15,000 miles) so they can be replaced before expensive damage is done.
The major components of a drum brake assembly are the brake drum, the brake shoes, the backing plate, the wheel cylinder(s), and all the hardware necessary to mount and connect the components (see illustration).
Rear drum brake assemblies also have self-adjusting mechanisms to keep the shoes within a predetermined distance from the drum, even as the lining material wears down.
There are two main designs of drum brake: duo-servo and leading/trailing. They are fairly similar in terms of hardware, although the duo-servo brake tends to have a few more components. The following shoe replacement procedure depicts a typical leading/trailing drum brake.
The dust created by the brake system is harmful to your health. Never blow it out with compressed air and don’t inhale any of it. An approved filtering mask should be worn when working on the brakes. Do not, under any circumstances, use petroleum-based solvents to clean brake parts. Use brake system cleaner only!
- Brake System Cleaner
- Brake Shoes
- Hardware Kit
- High-Temperature Brake Grease
- Jack and Jackstands
- Lug Wrench
- Filtering Mask
- Safety Glasses or Goggles
- Screwdriver or Brake Adjusting Tool
- Brake Spring Tool (optional) or Locking Pliers
- Brake Hold-Down Tool (optional) or Pliers
- Before beginning the job, purchase a service manual for your vehicle. It contains essential information for getting the job done safely and correctly the first time.
- Park the vehicle on a level surface, then place blocks in front of the front wheels. Loosen the rear wheel lug nuts, then raise the rear of the vehicle and support it securely on jackstands. Remove the wheels.
- Release the parking brake and remove the brake drum.
- Look for a retaining screw or screws; if any are present, remove them. Slide the drum off the hub or axle flange. If it sticks, apply penetrating oil to the area around the wheel studs and the center of the drum where it meets the flange, then let it soak in awhile and try again
- If the drum is still stuck, look for threaded holes in the face of the drum. If any are present, thread bolts of the proper size and thread pitch into the holes and tighten them a little at a time, alternating so as to push the drum off evenly. If no such holes are present, you might have to use a little force; try rapping on the face of the drum in the area of the flange to break the rust bond.
- If you can pull the drum off the flange but can remove it more than just a little, you'll have to retract the brake shoes. Look for a rubber plug on the brake backing plate. If one is present, remove it and, using a screwdriver or brake adjusting tool, turn the star wheel on the adjuster to retract the shoes. Note: Some drum brakes use other types of adjusters; your manual will show you how to retract the shoes on your particular vehicle.
- When replacing brake shoes, it's a good idea to have the drums resurfaced. Resurfacing the drums will get rid of imperfections in the friction surface of the drum, as well as out-of-round and taper conditions. Most auto parts stores can provide this service.
- The following photo sequence illustrates a typical leading/trailing drum brake shoe replacement procedure, but be sure to follow the procedure in your repair manual, as it will be specific to your vehicle.
Before removing anything, wash the brake assembly with brake system cleaner and allow it to drip dry into a pan - DO NOT USE COMPRESSED AIR TO BLOW BRAKE DUST FROM PARTS!
- Unhook the lower spring and remove it.
The upper spring can now be removed from the adjuster lever - note how it engages.
Remove the adjuster lever.
Remove the star-wheel assembly.
Depress the leading shoe retainer and turn it to remove it.
Remove the leading brake shoe.
Remove the trailing shoe retainer and allow the shoe to come free.
Pry open the clip to disconnect the parking brake lever from the trailing shoe.
Lubricate the backing plate contact points with high-temperature grease after thoroughly cleaning it.
Crimp the clip to attach the new trailing shoe to the parking brake lever.
Install the pin through the backing plate and the trailing shoe.
Install the spring and the retainer to the pin.
Use the special tool to compress the spring and engage the retainer.
Perform the same procedure on the leading brake shoe.
Clean the star-wheel adjuster and lubricate it lightly.
Install the star-wheel assembly with the star to the front.
Install the adjuster lever.
Install the upper spring, hooking it into the adjuster.
Install the lower spring.
Adjust the star-wheel to give a very light drag when the brake drum is turned, then back it off so the shoes don't rub. After reassembly is complete, be sure to test the brakes before driving the vehicle in traffic.