How to replace drum brakes
Drum brakes are not seen on every model of car these days, but they are often still used for rear wheel brakes, since they are cheaper to produce, and it is easier to attach the emergency brake system to a drum brake. Older cars use drum brakes on all wheels, as well. Replacing drum brakes is a repair which can be done at home, but requires the right equipment and careful attention to detail, and is best undertaken if you already have experience with DIY car repair. You will want to set aside a few hours for this task, and if you are not familiar with brake systems, you will want a Chilton's repair guide for your vehicle to consult as a reference. Remember that you will want to replace the drum brake on one wheel at a time, so that you have the other wheel as a reference point in case of confusion.
You will want the following tools for this project:
- New brake shoes
- Brake spring pliers
- Brake retainer tool
- Brake drum micrometer
- Auto jack
- Jack stands
- Wrenches, including a lug wrench and torque wrench
- Pliers or vise grips
- Hammer
- Chisel
- Grease for lubrication (white lithium grease works best)
- Brake cleaning spray
- Latex gloves
- Dust mask
- Digital/Polaroid camera
- Repair manual for vehicle
Removing the drum brakes:
- Find the master cylinder on your vehicle, and drain about half of the brake fluid into a sealed container. Dispose of the brake fluid properly, and make sure you have new brake fluid to add later.
- Use a lug wrench to loosen the lugs on the wheels a couple of turns.
- Raise the vehicle on one side using a jack, and place onto a jack stand. Do the same with the other side of a car.
- Remove the lug nuts as well as the wheels.
- For a rear-wheel drive vehicle, look for a round clip near the wheel studs, and remove it with wire cutters. Don't worry about breaking it, since its only used when the vehicle is being built. Then remove the brake drum, and rotate the brake adjustment screw to change the adjustment if brake lining is dragging against the drum. The brake adjustment screw is a squat screw next to the adjustment lever, and you will be able to see that this lever adjusts the distance between the brake shoe and the drum itself..
- For a front-wheel drive vehicle, simply remove the wheel cap and wheel bearings, and slide off the brake drum. If you're encountering a lot of resistance, rotate the brake adjustment screw, or apply some lubricant between the drum and the axle.
- Take a picture of the remaining brake hardware or have a diagram from the owner's manual handy to use as a reference.
- If the drum brake has a parking brake cable, disconnect it. This cable is connected to a parking brake lever by a clip and pin. Spread the clip apart with a screwdriver, and knock the pin out with a hammer.
- Locate the springs that hold the brake shoes against the wheel cylinder. Remove the return springs first, and then the hold-down springs, which are right on the brake shoes.
- Remove remaining brake hardware.
- Remove the brake shoes as a pair.
- Remove the self-adjusting spring and screw assembly from the brake shoes.
- If you are only replacing the brake shoes, and keeping your old drum brake, check the drum to make sure it is still safe to use. Use a brake drum micrometer to make sure that the brake drum size is within the oversize limit. This limit will be stamped on the brake drum. Then, use sandpaper to smooth the brake drum surface, making sure it stays within the limit. Put lubricant on the contact points of the drum. Use brake cleaning spray to ensure that your drums are clean before installing them.
Replacing the drum brakes:
- Align the brake shoes against the backing plate., leading shoe first If you're replacing the shoes, make sure that their hole pattern is the same as your old brake shoes.
- Re-attach the self-adjusting spring and screw assembly, and screw in the screw assembly.
- Use your photo or diagram to put in your brake drum the same way, and re-attach the parking brake cable and hold-down springs using pliers.
- Put the return springs back on to the brake shoe.
- Replace the brake drum, and make sure it can spin freely against the brake lining when rotating the brake adjustment screw.
- Re-install the wheel assembly.
- Check the master cylinder again, and replace brake fluid as needed. Make sure that the brake pedal feels right before lowering vehicle.
- Lower the vehicle and take it for a test drive, making sure to not drive too fast or apply the brakes too suddenly or roughly, since it will take a few hundred miles for the brake lining to become properly burnished.
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