Brakes - Pulsation/Shudder: Overview
NO: 05-08-98GROUP: Brakes
DATE: Dec. 18, 1998
SUBJECT:
Brake Pulsation/
Shudder
MODELS:
1995 - 1999 (FJ) Avenger/Sebring/Talon
SYMPTOM/CONDITION:
During braking, some vehicle may exhibit a condition where the steering wheel shakes or the brake pedal pulsates.
DISCUSSION:
In most cases the cause for this condition is excessive rotor thickness variation and/or runout. Following are the most common factors that contribute to pulsation/shudder:
Rotor Runout
Rotors that have runout will continue to get worse as the vehicle accumulates mileage. Runout of the rotor itself or axle to hub runout can contribute to this problem.
Brake Drag
If the stop lamp switch or booster push rod is incorrectly adjusted (too tight), the brake pads will be in heavier than normal contact with the rotor causing accelerated pad wear and eventually uneven rotor wear.
Rust On Rotor
Vehicles that are left stationary for extended periods of time build rust on the brake rotors. Over time this can cause permanent variation or runout of the rotors.
In some cases a combination of the above factors accumulate to cause brake pulsation or shudder. In these instances hub mount on-car rotor turning is the specified method to bring the excess runout within specification. Replacement of rotors alone may not help this condition or may only temporarily help the condition.
If brake pulsation or shudder is experienced, use the charts and procedures to make appropriate repairs to the braking system.
PARTS/EQUIPMENT REQUIRED:
1 PC-CHRYSLER Lathe, Pro-Cut Hub Mount On Vehicle Brake (See PSE
Catalog for all models available)
AR(1) 04897150AA Cleaner, Brake Parts
1 NPN Dial Indicator
1 NPN Gauge Block
1 NPN Micrometer, Brake Rotor
1 NPN Caliper, Vernier
1 NPN Wrench, Inch Pound Torque
POLICY: Information Only