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34 90 ... Troubleshooting Brake System

TROUBLESHOOTING BRAKE SYSTEM

Fault Cause Remedy
Brakes pull to one side
  1. Tyre inflation pressure not in keeping with regulations
  2. Unevenly worn tyre treads
  3. Oil on pads/liners
  4. Wrong type of pads/liners
  5. Guide bolts dirty or damaged
  6. Axle geometry not correct
  7. Corrosion in floating calipers
  8. No shock absorber action
  9. Pad of one caliper worn
  1. Correct tyre inflation pressure
  2. Change or replace tyres
  3. Replace brake pads,

    Check for causes

  4. Replace brake pads,

    Check for causes

  5. Replace guide bolts
  6. Check wheel alignment
  7. Remove and install, repair or replace floating calipers
  8. Check shock absorbers, replace if necessary
  9. Replace brake pads, check floating caliper
Brakes excessively hot while driving
  1. Compensating port in brake master cylinder blocked
  2. Swollen rubber parts due to use of wrong brake fluid
  3. Bleeder hole on expansion tank blocked
  4. Corroded floating calipers
  5. Handbrake lever not released fully
  1. Replace master brake cylinder
  2. Replace master brake cylinder
  3. Clean expansion tank
  4. Remove and install, repair or replace floating calipers
  5. Check handbrake and handbrake Bowden cables,

    repair if necessary

Poor braking effect in spite of great force on pedal
Travel at brake pedal normal
Brake pads oil-splattered or burnt; wrong type of brake pads Replace brake pads
Poor braking effect in spite of great force on pedal
Travel at brake pedal too short
Brake booster malfunctions - engine vacuum Check brake booster
Poor braking effect in spite of great force on pedal
Travel at brake pedal too long
One brake circuit failed due to leaks or damage Leakage test of brake system
Brake pedal can be pressed down softly and springily
  1. Air in brake system
  2. Not enough brake fluid in expansion tank
  3. Overheated brake fluid - vapour lock due to excessive water content in brake fluid or excessive brake loads
  1. Bleed brakes
  2. Top up or change brake fluid

    Bleed brakes

  3. Change brake fluid,

    Bleed brakes

Brake is bled and readjusted, but brake pedal can be pressed down too far
  1. Primary cup seal in brake master cylinder damaged
  2. Leaking separating cup seals on floating piston of brake master cylinder
  3. Leak in brake system
  1. Replace master brake cylinder
  2. Replace master brake cylinder
  3. Leakage test of brake system
Uneven pad wear
  1. Wrong type of pads/liners
  2. Dirty floating caliper recesses, damaged caps
  3. Corrosion in floating calipers
  4. Swollen rubber ring for piston control
  1. Replace brake pads
  2. Remove and install, repair or replace floating calipers
  3. Remove and install, repair or replace floating calipers
  4. Remove and install, repair or replace floating calipers
Brake pads worn at angle
  1. Wheel-bearing play excessive
  2. Brake disc not aligned with floating caliper
  3. Corrosion in floating calipers
  4. Angular brake-disc wear
  5. Minimum pad thickness undershot
  6. Spring force insufficient
  7. Guide bolts damaged
  1. Replace wheel bearings
  2. Check floating caliper installation
  3. Remove and install, repair or replace floating calipers
  4. Replace brake discs
  5. Replace brake pads
  6. Replace spring
  7. Replace guide bolts
Seized brake pads, pad does not move off brake disc
  1. Dirty floating caliper recesses, damaged caps
  2. Corrosion in floating calipers
  3. Compensating port in brake master cylinder blocked
  1. Remove and install, repair or replace floating calipers
  2. Remove and install, repair or replace floating calipers
  3. Replace master brake cylinder
Brakes squeal or rattle
  1. Wrong type of pads/liners
  2. Dirty floating caliper recesses
  3. Spring force insufficient
  4. Brake disc not aligned with floating caliper
  5. Brake-disc runout
  6. Excessive thickness deviation within braking surface
  7. Liner wear excessive or one-sided
  8. Rust edges on brake discs
  9. Pad loose
  10. Wheel-bearing play excessive
  1. Replace brake pads
  2. Remove and install/clean floating calipers
  3. Replace spring
  4. Check floating caliper installation
  5. Replace brake discs
  6. Measure brake disc thickness

    Replace discs

  7. Replace brake shoes
  8. Replace brake discs
  9. Replace brake pads
  10. Replace wheel bearings
Brake-pedal dead travel excessive
  1. Wheel-bearing play excessive
  2. Brake disc not aligned with floating caliper
  3. Brake-disc runout
  4. Excessive thickness deviation within braking surface
  5. Brake system leaking
  6. Air in brake system
  7. Wrong type of pads/liners
  1. Replace wheel bearings
  2. Check floating caliper installation
  3. Replace brake discs
  4. Measure brake disc thickness

    Replace discs

  5. Leakage test of brake system
  6. Bleed brakes
  7. Replace brake pads
Jammed piston in brake caliper
  1. Dirty floating caliper recesses, damaged caps
  2. Brake disc not aligned with floating caliper
  3. Pistons corroded in floating calipers
  1. Remove and install, repair or replace floating caliper
  2. Check floating caliper installation
  3. Remove and install, repair or replace floating caliper
Pulsating effect on brake pedal
  1. Wheel-bearing play excessive
  2. Brake disc not aligned with floating caliper
  3. Brake-disc runout
  4. Excessive thickness deviation within braking surface
  1. Replace wheel bearings
  2. Check floating caliper installation
  3. Replace brake discs
  4. Measure brake disc thickness

    Replace discs

Handbrake effect insufficient
  1. Brake pad fouled by oil
  2. Excessive free play
  3. Corroded transmitting elements

Replace discs
  1. Replace brake pads,

    determine cause

  2. Adjust handbrake
  3. Remove and install handbrake,

    check brake caliper, Bowden cables, replace if necessary


check brake caliper, Bowden cables, replace if necessary