Brake - Roughness During Application
Article No.98-5A-18
03/18/98
^ BRAKES - ROUGHNESS DURING BRAKE
APPLICATION - DIAGNOSIS AND REPAIR SERVICE
TIPS
^ VIBRATION - DISTORTED REAR BRAKE DRUM -
VEHICLES BUILT BETWEEN 11/93 AND 9/95
FORD:
1993-97 THUNDERBIRD
LINCOLN-MERCURY:
1993-97 COUGAR
ISSUE:
Some vehicles may exhibit brake roughness (brake pedal pulsation, steering wheel shake and/or nibble) under light brake applications from 105 to 0 km/h (65 to 0 mph). This may be caused by high lateral runout of the brake rotors and/or brake drums.
ACTION:
Refer to the following Diagnostic and Service Procedures for details.
DIAGNOSTIC PROCEDURE
1. Road test vehicle and perform 3 to 6 light brake applications from 105 to 32 km/h (65 to 20 mph). Evaluate brake pedal pulsations (if any) and steering wheel shake or nibble (if any).
2. Road test vehicle and perform 3 to 6 heavy brake applications from 105 to 32 km/h (65 to 20 mph). Be careful not to overheat the brake system. Evaluate brake pedal pulsations (if any) and steering wheel shake or nibble (if any).
3. If any brake roughness is evident, proceed to the Service Procedure. If no brake roughness is evident, return the vehicle to the customer.
The following systems and components may also affect brake roughness. Perform checks on each system to verify there is no damage or out-of-specification components.
^ Alignment
^ Suspension - Bushings and Ball Joints
^ Tire Condition and Pressures
^ Wheel Balance
SERVICE PROCEDURE
REAR DRUM VEHICLES ONLY
Remove and inspect the rear drums for distortion around the stud holes. If the vehicle was produced between 11/93 and 9/95, replace the rear drums.
REAR DISC VEHICLES ONLY
1. Remove the front wheels and calipers. Remove any corrosion from the back side of the wheel mount surfaces and. check caliper slides for binding, corrosion or damaged boots and seals.
2. Flat-sand the brake linings with emery cloth if serviceable thickness is present, otherwise replace the brake linings.
3. Remove the front rotors and remove any corrosion on the inner hat face and hub mounting surfaces.
4. Check hub runout using a dial indicator. If runout is greater than 0.05 mm (0.002"), replace the hub.
5. If the front rotors are within specification (rotor thickness greater than 24.7 mm/0.974") machine the front rotors on the vehicle. Refer to TSB 94-25-2 for details. If the rotors are out-of-specification, replace the rotors. In either case, be sure to index the rotor with the hub stud for matching mounting.
NOTE:
PRIOR TO ASSEMBLY, MAKE SURE THERE IS NO CONTAMINATION ON THE HUB, ROTOR, AND WHEEL MOUNTING SURFACES. ANY CONTAMINATION ON THESE SURFACES MAY ADVERSELY AFFECT RUNOUT AND LEAD TO BRAKE ROUGHNESS REGARDLESS OF OTHER BRAKE REPAIRS PERFORMED.
6. Apply nickel anti-seize to the hub outer face and to the outer rotor hat surface during assembly. Avoid getting anti-seize on the studs.
7. Install wheels making sure to index the wheel with the hub (valve stem aligned with hub yellow dot) and torque the wheels to 115-142 N.m (85-105 lb-ft).
8. Test drive vehicle and verify the concern has been repaired. If concern is still apparent, repeat Steps 2 through 7 for the rear discs.
Parts Block
OTHER APPLICABLE ARTICLES: 94-25-2
SUPERSEDES:96-4-3
WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage
OPERATION DESCRIPTION TIME
985A18A Replace Rear Drums - 0.5 Hr.
Both
985A18B Replace Front Brake Pads 1.0 Hr.
(Not To Be Used With
Operation C)
985A18C Sand Front Brake Pads 1.0 Hr.
(Not To Be Used With
Operation B)
985A18DT Additional Time To 0.3 Hr.
Replace Front Hubs - Both
985A18D Additional Time To 0.2 Hr.
Replace Front Hub - One
985A18ET Additional Time To 1.2 Hrs.
Machine Rotors - Both
985A18E Additional Time To 0.6 Hr.
Machine Rotor - One
985A18FT Additional Time To 0.6 Hr.
Machine Rotors Using
Pro-Cut - Both
985A18F Additional Time To 0.3 Hr.
Machine Rotors Using
Pro-Cut - One
985A18GT Additional Time To 0.3 Hr.
Replace Front Rotors -
Both
985A18G Additional Time To 0.2 Hr.
Replace Front Rotor - One
DEALER CODING
CONDITION
BASIC PART NO. CODE
1125 - FRONT ROTOR
REPLACEMENT 13
1126 - REAR DRUM
REPLACEMENT 13
OASIS CODES: 301000, 303000, 304000, 703000, 703400