The common maintenance for drum brakes is to replace the brake shoes. Some drum brakes provide an inspection hole on the back, which allows you to check how much material is left on the brake shoes. When the friction material has worn down to the point where the rivet is only 0.8 millimeters long, the brake shoe should be replaced. If the friction material is bonded to the rear floor (not with rivets), the brake shoes should be replaced when the remaining friction material is only 1.6 millimeters thick.

Similar to the situation in disc brakes, deep scratches may sometimes appear on the brake drum due to wear and tear. If the worn brake shoes are used for too long, the rivets that fix the friction material at the rear will grind out grooves on the drum. Drums with severe scratches can sometimes be repaired by re polishing. Disc brakes have a small allowable thickness, while drum brakes have a large allowable diameter. Due to the contact surface being located inside the drum, the diameter will increase when you remove material from the drum brake.

maintenance

When the pads wear out, more space will be created between the brake shoes and the drum. When the car comes to a stop during reverse, it pushes the brake shoes to press against the drum. When the gap becomes large enough, the adjusting rod will shake enough to advance the adjuster gear by one tooth. The regulator has a bolt like thread on it, so it can be loosened slightly when rotated and extended to fill the gap. Whenever the brake shoes wear out a little, the regulator will move forward a little more, so it always keeps the brake shoes close to the drum. Some car regulators will activate when using emergency brakes. If the emergency brake has not been used for a long time, the regulator may not be able to be adjusted again.

Therefore, if your car is equipped with such a regulator, you should use the emergency brake at least once a week.