Replacing Rear Brake Shoes
Most cars have a brake shoe and
drum style of brake system in the rear of the vehicle.
Drum brakes are not quite as efficient
as their counter part the disc brake
system. Drum brakes are easily produced and can be used on the rear of a vehicle
were only about 30% of the braking is created. Sometimes special brake shoe removal
tools are required. Rear brake shoe performance can be affected when wet and the
braking ability can be greatly diminished.
Before you begin park the car on a level surface, block the front tires to prevent
the vehicle from moving. You will be dealing with asbestoses which is a hazardous
material so wear protective gloves, clothing and eyewear.
Tools and Supplies Needed to Complete this Job
1. Floor Jack
2. Jack stands
3. Lug Wrench
4. Brake cleaner
5. Replacement Brake Shoes
6. Brake Shoe Removal Tool
7. Screwdriver set
8. Pliers
9. Shop towels
10. Hammer
Instructions
Step 1 - Identify Rear Brake Shoes and Wheel
Cylinder Components
Identify Rear Brake Shoe Components
Remove brake drum to
inspect brake shoes for wear. If the brake material is less than 1/8 inch, they
need to be replaced in most cases. Check the
wheel cylinder for leaks.
Remove the dust boot from the side of the wheel cylinder and check for brake fluid
leaks. If brake fluid is present the wheel cylinder needs replacing. Also check
brake shoe hardware, return and mounting springs, and replace if damaged or broken.
Step 2 - Removing the Brake Shoes and Wheel
Cylinder
Release Rear Brake Spring
Use the brake spring tool to remove the return spring to each of the brake shoes.
Step 3 - Removing Brake Shoe Mounting Springs
Release Rear Brake Shoe Hold Downs
Hold the rear of the retainer pin. Insert brake shoe removal tool over retainer
clip, press down and twist counter clockwise. Remove spring and retainer. Inspect
and replace as needed. Then remove the rear brake shoes and remaining hardware.
Match the old brake shoes to the new brake shoes. Both sets should match up exactly.
Then transfer hardware to new brake shoes.
Step 4 - Removing Wheel Cylinder
Removing the Wheel Cylinder
After the rear brake shoe and hardware pieces have been removed, install line
wrench onto brake line at the wheel cylinder and loosen the mounting fitting, then
remove it. Note: brake fluid will leak from line when loosened. Remove wheel cylinder
mounting bolts and replace wheel cylinder with new unit. Re-attach and tighten brake
lines and retighten wheel cylinder mounting bolts. Then clean and lube the brake
shoe backing plate.
Step 5 - Reassemble With New Brake Parts
Reassemble with New Brake Part Components
Reassemble with new brake parts and make sure all the brake hardware is mounted
correctly. Note: when changing rear brake shoes, only disassemble one side at a
time so you always have a reference copy on the side that is still together.
Step 6 - Adjusting Brake Shoes
Adjusting Rear Brake Shoes
After brake shoes have been installed they need to be adjusted. Normally they
are self adjusting but the first time after installation, a primary adjustment must
be made. After installing the brake drum and spinning it on the bearing hub, adjust
the brake shoes to lightly contact the brake drum and recheck regularly. After the
brake shoes are adjusted,
bleed the brake system
until free from air in the brake fluid and leaks. Test brake system before driving.
CAUTION: DO NOT DRIVE OR MOVE VEHICLE UNTIL NORMAL BRAKE PEDAL
OPERATION IS PRESENT!
Common Problems
- Brake shoes wear out and grind
to metal due to lack of maintenance.
-
Low brake pedal due
to improper adjustment.
- Looses partial braking ability when wet.
Rear Brake Shoes and Drums
|
Rear Brake Shoes - The rear brake shoe is actuated by
wheel cylinders that force the brake shoe against the brake drum with hydraulic
pressure from the master cylinder.
|
|
Wheel Cylinder - Brake fluid pressure from the
brake master
cylinder is applied to the brake wheel cylinder forcing the brake shoe
against the brake drum.
|
|
|
Brake Drum - The brake drum is used to slow the wheel
speed through braking action. The brake shoes are applied to the drum to
cause friction.
|
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