When should brake shoes be replaced?
The service life of these components is 60,000 km or more on average. However, it can be reduced in case of bad driving habits. FAor example, not fully releasing the handbrake leads to the shoes rubbing against the drums and, as a result, quickly wearing out.
To monitor the condition of the brake shoes, use a special inspection hole on the drum backing plate. You can estimate the thickness of the friction linings with the car raised. If the size of the components reaches the minimum limit usually specified by the manufacturer, the parts must be replaced. Other signs of wear are the vibration of the brake pedal, increased braking distance, as well as the car skidding when braking.
What is the minimum allowable thickness of brake shoes?
The minimum allowable thickness of the friction lining of the parts is specified in the car’s service manual. Usually, it is 1.5–2 mm. If it is more convenient for you to measure the thickness of the lining together with the base, then this figure mustn’t be less than 5.0 mm. In practice, it’s better not to let the brake system elements reach this point.
If the friction lining is worn below the allowable limit, the braking efficiency significantly reduces as the friction coefficient between metal surfaces is much lower. Moreover, due to abrasion of the shoe and the drum against each other, the hold down pressure may decrease. In some cases the friction lining can detach from its base and get deformed, which may cause total breakdown of the brakes.
Do I need to replace brake shoes in pairs?
Specialists recommend replacing these parts as a set on an axle. Changing them on one wheel only may reduce stability when braking. When carrying out this job, clean all elements of the system of dirt and check whether the brake mechanisms are properly greased. If the springs are corroded, they must also be replaced. Inspect the condition of the wheel cylinder boots too. Air in the system or brake fluid leakage reduce the efficiency of even new components. You should also check that the handbrake is in good working order.
What tools are needed to change brake shoes?
Depending on the make, model and version of your car, for replacement of the brake shoes you may need a set of special pliers, screwdrivers with specifically shaped blades, and hooks. With the help of these accessories it is convenient to demount and install spring washers and return springs. The tool sets can include clamps for brake pistons and hoses, and accessories for compressing springs and adjusting gaps.
Replacement of the shoes in a drum brake is more complicated than changing disc brake pads. An experienced specialist can do this job in about an hour. Beginners may need up to 3 hours.