TROUBLESHOOTING 309
Condition
Possible Cause
Squealing brakes
1. Glazed brake lining.
2. Saturated brake lining.
3. Weak or broken brake shoe retaining spring.
4. Broken or weak brake shoe return spring.
5. Incorrect brake lining.
6.- Distorted brake shoes.
7. Bent support plate.
8. Dust in brakes or scored brake drums.
9. Linings worn below limit.
10. Uneven brake lining wear.
11. Heat spotted brake drums.
Chirping brakes
1. Out of round drum or eccentric axle flange pilot.
Dragging brakes
1. Incorrect wheel or parking brake adjustment.
2. Parking brakes engaged or improperly adjusted.
3. Weak or broken brake shoe return spring.
4. Brake pedal binding.
5. Master cylinder cup sticking.
6. Obstructed master cylinder relief port.
7.
Saturated brake lining.
8.. Bent or out of round brake drum.
9. Contaminated or improper brake fluid.
10. Sticking wheel cylinder pistons.
11. Driver riding brake pedal.
12. Defective proportioning valve.
13. Insufficient brake shoe lubricant.
Hard pedal
1. Brake booster inoperative.
2. Incorrect brake lining.
3. Restricted brake line or hose.
4. Frozen brake pedal linkage.
5. Stuck wheel cylinder.
6. Binding pedal linkage.
7. Faulty proportioning valve.
Wheel locks
1. Contaminated brake lining.
2. Loose or torn brake lining.
3. Wheel cylinder cups sticking.
4. Incorrect wheel bearing adjustment.
5. Faulty proportioning valve.
Brakes fade (high speed)
1. Incorrect lining.
2. Overheated brake drums.
3. Incorrect brake fluid (low boiling temperature).
4. Saturated brake lining.
5. Leak in hydraulic system.
6. Faulty automatic adjusters.
Pedal pulsates
1. Bent or out of round brake drum.
Brake chatter and shoe knock
1. Out of round brake drum.
2. Loose support plate.
3. Bent support plate.
4. Distorted brake shoes.
5. Machine grooves in contact face of brake drum (Shoe Knock).
6. Contaminated brake lining.
7. Missing or loose components.
8. Incorrect lining material.
9. Out-of-round brake drums.
10. Heat spotted or scored brake drums.
11. Out-of-balance wheels.