Drum brake shoes: common defects and their signs

1. Wear-out.
   • Noticeable thinning of the drum brake shoe.
   • Enlarged free travel of the brake pedal.
   • Squealing or screeching sound at braking.
   • Prolonged braking path of the vehicle.
2. Slackening of the brake shoe spring.
   • One of the wheels is being braked when the brake pedal is released.
   • Brakes are vibrating or producing specific squeaking sound.
   • The pedal jams in the pressed position after releasing it.
3. Soiling or oiling of the friction pads.
   • Lowered operational efficiency of the drum brakes.
   • Foreign sounds (squeaking, knocking) during braking.
   • Spontaneous change of the vehicle trajectory during braking.
   • Increased resistance of the brake pedal.

How to replace drum brake shoes?

Broken components are to be immediately replaced. It is recommended to perform drum brake shoes replacement on both vehicle sides.

The process can have its peculiarities according to the car model; generally, the algorithm of unassisted replacement is the following:

• Loosen the fastening bolts or nuts on the wheel, lift the car body with the help of a jack, then completely unscrew all fasteners and demount the wheel.
• Secure the vehicle in place with the help of car wheel chocks.
• Unscrew guide pins and remove the brake drum.
• Disconnect the guide spring and the rod of the parking brake.
• Demount the brake shoe spring.
• Disconnect brake shoes from the pins of the wheel brake cylinder, remove them.
• Install a serviceable component and assemble everything in the reversed order.

You should replace brake shoes as a set.
Perform scheduled diagnostics of brake shoes every 30 000 km.
When replacing brake shoes, inspect the brake drum visually, measure its inner diameter. If the wear limit has been reached, replace the brake drum.
Average operational lifetime: 60 000 – 70 000 km.

Types:

1. By designation:
   • for the main brake;
   • for the parking brake.