Drum brakes are still fairly common in vehicles today, despite having been more or less overthrown by the much more efficient and reliable disc-based brakes prevalent in the market. The latter has pretty much become the standard in vehicles. Drum brakes, meanwhile, are used mostly on the rear axles of vehicles, and as parking brakes.
Drum brakes operate using friction-lined “shoes” inside the drum, having a longer service life as a result. Servicing a drum brake is not all that hard if you know what you are doing, but the procedure is lengthy. Following are the main steps to take when you need your car’s drum brake replaced.
Prepping the Vehicle and Removing the Brake Shoes
- Loosen the vehicle’s lug nuts, after taking off any wheel hubcaps and center wheel covers. This is done more easily when the car’s weight is fully resting on the wheels.
- Raise the rear end and secure the car on jack stands. The parking brake is useless here, so use wood blocks or tire chocks to prevent rolling.
- Take out the wheel to gain access to the brake drum. Make sure the area is well ventilated, because brake dust can be a health hazard sometimes.
- Take out the brake drum. This can be done by moving it back and forth, and then pulling it out. The parking brake must be disengaged first.
- Clean the assembly. This includes the springs, shoes, and wheel cylinder. With a drain pan under it, spray down any dirty areas of the assembly using brake cleaner.
- Check the brakes. Measure the brake shoes using a micrometer; if the thickness is under a sixteenth of an inch, you need a replacement. The drum should not be carrying grooving, scoring, or cracking either.
- Take the drum brake assembly apart. To do that, you need to first take out the retaining springs on the brake shoe using nose pliers. The top spring comes first, and reduces the overall tension.
- Take out the drum shoes. These would be secured with washers and pins, so take those out first. When that is done, you should be able to pull out the drum shoes.
- Check the wheel cylinder for leaks. With the shoes and springs taken out, you should be able to find the wheel cylinder and check it for leaks. If you find any, then a replacement is due.
- Take out the retainer clip for the parking brake cable. Pry it up using a flathead, or simply twist it out using pliers. Keep this clip safe.
Putting in the New Brake Drum and Shoes
- Clean the backing plate and then lubricate it. Use brake cleaner and disc brake lubricant, in that order. Apply the latter to the bosses, pin anchor, and the pivot surface of the actuating lever.
- Set up the retaining clip and parking brake lever. The pin will need to be slid in through the new shoe, so that the retaining clip stays in place.
- Fit the adjusting screw spring and the adjusting screw assembly. This is simple enough to do, and then you can move on to the next step.
- Attach the new shoes on the hub. Start reassembling by doing this, and secure the shoes using pins and washers of the right types.
- Put back the tensioning springs. This needs to be done in the reverse order to what you did earlier, which means you should go bottom to top.
- Put in the hold-down springs and pins to complete the brake drum assembly, so that you can begin arranging everything the way it was.
- Put in the return springs at their proper spots on the brake, so that the required tension is in place once again.
- Adjust the brakes to make the brake shoes expand. This can be done either with a screwdriver, or with a dedicated brake spoon.
Installing the New Drum and Replacing the Wheel
- Prep the new drum for installation by spraying brake cleaner to take off any filmy coating designed to avoid the rust during shipping.
- Attach the drum brake on top of the brake shoes, and fix it to the hub. If you face issues sliding it in, try adjusting the brake shoes to make room.
- Perform final adjustments on the drum. Ensure that the shoes have the right amount of tightness, and fix any problem thereby turning the adjuster.
- Put back the wheel and the tire, screw in the lug nuts, and make sure these are not too tight.
- Take out the jack stands, and lower the vehicle back onto the ground. Take out the wheel chocks.
Repeat the above steps for the remaining rear wheel’s brake drum, and after adjustments, test your brakes to make sure that they are working right.