Pinpoint Test A: Brake Vibration/Shudder

• Check that the wheel and tires are correct for the vehicle. Inspect the tires for abnormal wear patterns.
• Road test the vehicle. Warm the brakes by slowing the vehicle a few times from 80-32 km/h (50 to 20 mph) using light braking applications. At highway speeds of 89-97 km/h (55-60 mph), apply the brake using a light pedal force.
• Is there a vibration/shudder felt in the steering wheel, seat or brake pedal? 

Yes 

GO to A4.

No 

GO to A2.

• Road test the vehicle. At highway speeds of 89-97 km/h (55-60 mph), apply the brake using a moderate to heavy pedal force.
• Is there a vibration/shudder? 

Yes 

For vehicles with ABS, GO to A3.

For vehicles with standard brakes, GO to A4.

No 

Vehicle is OK. VERIFY condition with customer. TEST the vehicle for normal operation.

• During moderate to heavy braking, noise from the hydraulic control unit (HCU) and pulsation in the brake pedal can be observed. Pedal pulsation coupled with noise during heavy braking or on loose gravel, bumps, wet or snowy surfaces is acceptable and indicates correct functioning of the ABS system. Pedal pulsation or steering wheel nibble (frequency is proportioned to the vehicle speed) indicates a concern with a brake or suspension component.
• Is the vibration/shudder vehicle speed sensitive? 

Yes 

GO to A5.

No 

The brake system is operating correctly.

NOTE: Begin at the front of the vehicle unless the vibration or shudder has been isolated to the rear.
• This test is not applicable to vehicles with drum-in-hat type parking brakes. For vehicles with drum-in-hat parking brakes, proceed to the next test. For all other vehicles, apply the parking brake to identify if the problem is in the front or rear brake. At highway speeds of 89-97 km/h (55-60 mph), lightly apply the parking brake until the vehicle slows down. Release the parking brake immediately after the test.
• Is there a vibration/shudder? 

Yes 

GO to A8.

No 

GO to A5.

• Check the front wheel bearings. Refer to WHEEL BEARING CHECK .
• Are the wheel bearings OK? 

Yes 

GO to A6.

No 

INSPECT the wheel bearings. ADJUST or REPAIR as necessary. TEST the system for normal operation.

• Check the front suspension for:
  • Broken or loose bolts.
  • Damaged springs.
  • Worn or damaged upper and lower control arm bushings.
  • Loose or rough front bearings.
  • Uneven tire wear.
• Are all the suspension components in satisfactory condition? 

Yes 

GO to A7.

No 

REPAIR or INSTALL new components as necessary. TEST the system for normal operation.

CAUTION: Do not use a bench lathe to machine brake discs.
NOTE: Follow the manufacturer's instructions to machine the brake discs. After machining, make sure the brake disc meets the thickness specification.
• Resurface the front brake discs or drums. Refer to BRAKE DISC MACHINING . Road test the vehicle.
• Is the vibration/shudder present? 

Yes 

GO to A8.

No 

Vehicle is OK.

• Check the rear suspension for:
  • Broken or loose bolts.
  • Damaged or worn springs or spring bushings.
  • Worn or damaged upper and lower control arm bushings.
  • Worn or damaged trailing arms.
  • Loose or rough rear bearings.
  • Uneven tire wear.
• Are all the suspension components in satisfactory condition? 

Yes 

GO to A9.

No 

REPAIR or INSTALL new components as necessary. TEST the system for normal operation.

CAUTION: Do not use a bench lathe to machine brake discs.
NOTE: Follow the manufacturer's instructions to machine the brake discs. After machining, make sure the brake disc meets the thickness specification.
• Resurface the front brake discs. Refer to BRAKE DISC MACHINING . Road test the vehicle.
• Is the vibration/shudder present? 

Yes 

CHECK the front suspension for wear or damage. RESURFACE the front brake discs. TEST the system for normal operation.

No 

Vehicle is OK.