The drum brake is a very simple system that has not really changed in its operation for decades. Whilst the materials have changed, the operation and application are essentially the same.
A drum brake system is made up of a number of mechanical components, these include:
- A backing plate with protruding wheel studs;
- A hydraulic wheel cylinder with an internal curved brake shoe;
- A pan shaped drum enclosure to cover all.
When the driver presses on the brake pedal, a hydraulic valve containing the brake fluid builds up pressure and applies it through a piston located in the wheel cylinder. The piston forces the shoe to expand, and this applies abrasive pressure to the wheel causing it to slow down. There is a strong retraction spring that forces the piston back into place when the pressure is released by lifting up the driver’s foot from the brake pedal.
The front-wheel shoe is called the primary, and the rear wheel shoe is termed the secondary.
Since drum brakes are so old in concept, their design proves that they work and current technologies have yet to determine a safer and cost-effective solution to replace them.
Reasons to Inspect and Change Brake Shoes
The brakes are the only component in your vehicle that can stop your car in an emergency as well as provide additional control together with your gears. There are different materials in play today, and some are extremely expensive, made up of composites that provide a smoother brake, a faster holding pattern and longer life with less heating from friction. Drum brakes today have a life span that varies between 30k to 100k miles and depends on whether there are the front or rear brakes since the rear brakes tend to be used more often than the front.
Worn Brake Signs
- Rubbing or Squealing sounds
- Steering wheel pulls to one side when braking
- Longer braking time
- Parking brake does not really work
To change the brake shoe, you will need around 2 hours of time and require the following tools:
- Jack Stands; to secure your car when working on it (do not work on it with only one jack in place)
- Car brake shoes; designed for your make and model of wheel
- Brake hardware kit; designed for your make and model of wheel
- Brake fluid
- Brake cleaner
- Special Brake tools including a hold-down remover and spring pliers
- Hand tools – such as a screwdriver, hammer
- High temp grease
- Drip tray
- Gloves – optional if you don’t mind dirty hands
- Mask; mandatory because brake dust is carcinogenic!
Step 1: Preparation
Park on a horizontal surface and your vehicle on jack stands. Release the hand brake lever.
Step 2: Remove the Tire
Unscrew the lugs holding your wheels in place and remove them one at a time.
Step 3: Remove the Brake Drum
You will notice a dust cap in your brake drum, pry that out using a screwdriver. If it is stuck, don’t force it, use a solvent to release the rust hold and then remove it. Under the dust cover is the axle bearing nut, take a ratchet and unscrew the axle bearing nut. Make sure to place the nut in a safe location you will need it to reinstall the drum. Now pull on the brake drum, maybe twist it slightly as you remove it from its mooring, Take heed that some brake drums rust solid and can be hard to remove. You can add solvent here too if required, or use a rubber head hammer to help dislodge it. You won’t need the old drum, the new drum you purchased will replace this one.
Step 4: Remove the Brake Shoe Spring
Take your pliers and detach the brake shoe springs, some cars have one spring, others have two. Do not do this with your fingers since some springs might nip them as you detach them. There is also a special spring disassembly tool, if you have one, use it. Do not apply too much pressure or you might damage the spring, you need these springs since you will reinstall them. You need to secure the retaining post from moving, hold it with your free hand.
Step 5: Remove the Brake Shoe Clips
Take the needle-nose pliers and use them to remove the clips that hold the brake shoe. There are usually two clips per pad. Again, make sure the clips are freed safely and without damage, or you will need to replace them.
Step 6: Remove the Brake Shoe Pads
Now you can remove the old brake shoe pads and place them next to the new ones you want to install. Check to see that they are identical.
Step 7: Cleaning up the components
This is optional, but I suggest now you take a break (excuse the pun) and clean up all the brake drum and shoe components that will be used again. Clean the axle area, make all threads clean and oiled or greased. Do not allow oil or grease to touch the pads.
Step 8: Installing the Pads and Adjuster Wheel
Now take all the components you’re cleaned up, and reassemble them back. Install the new pads into place. During this step, you will need to reset the parking brake adjuster. This is done together with the re-installation of the springs. Push the adjuster wheel away from the pin when installing it. In some instances, you might need to wind the thread inwards to shorten the adjuster. Once the adjuster is installed, it will self adjust.
Step 9: Installing the Spring
When installing the spring, hold it away from the cable end and take your pliers to pull the spring away. This will provide you with an exposed cable, making it easier to install. Consider using locking pliers to hold the spring back.
Step 10: Installing the Shoe
Take the newly assembled brake shoe with pads and place it against the backing plate. Now install the clips to hold the brake. If you have a kit that comes with new clips, use those instead of the old ones.
Step 11: Assemble the Return Springs
Its time to reconnect the return springs. Take the pliers again, don’t do this barehanded, and place the springs back into their location. Make sure not to damage them.
Step 12: Secure the drum
Now its time to take the new drum and place it over the shoe, screw in the axle nut and apply the relevant torque. Re-attach the dust cover and remount the wheel.
You are ready to go!