Brakes - Rotor Service Update
Article No. 85-9-8 Supercedes 85-4-12
BRAKE ROTOR SERVICE - UPDATED DIAGNOSIS AND SERVICE CHART
FORD 1983-85 ALL
LINCOLN-MERCURY 1983-85 ALL
NOTE: Reprint of 85-4-12 to change title and correct copy.
Technical Service Bulletin Number 82-21-5 refers to sanding the corrosion from the braking surface of the rotor for a brake roughness condition. Sanding is not effective for removing rust/corrosion or the
black discoloration caused by semi-metallic brake linings on rotors. Rust/corrosion on the rotor surfaces does not affect performance unless it is thick enough to cause pulsation. The procedure in Condition 5, Step 1, should be revised to read as follows below. TSB 82-21-5 is being republished for your convenience.
Continuing improvements by brake rotor suppliers in the overall quality level of manufacture and control of critical dimensions has made this change in procedure possible.
Essentially, brake rotor service consists of sanding the braking surface or replacing the rotor when sanding is not effective.
Following is an updated Brake Diagnostic and Service Chart. It lists most of the conditions a customer will mention when brake service is required, plus the probable causes and the recommended service.
CONDITION POSSIBLE CAUSE SERVICE
1. Squeal - A loud, sharp, high- 1. Brake lining and/or rotor surface 1. Remove caliper assembly from
pitched moderately prolonged contamination evidenced by glazed spindle and remove inner and outer
sound that occurs while braking. surfaces. linings. Rotor removal from rear
Occasional or intermittent brake drive vehicles is not necessary.
squeal may result from Hand sand glaze from linings and
environmental conditions such as both braking surfaces or rotor. Use
cold, heat, wetness, snow, salt, Garnet Paper 100A (medium grit) or
mud, etc. This condition is aluminum oxide 150J (medium).
not a functional one and will
not affect braking effectiveness.
2. Disc brakes - Missing or damaged 2. When the linings are not worn,
brake pad insulators. replace the brake pad insulators.
(See master parts catalog for
insulator availability).
3. On drum brakes - Loose lining 3. Inspect, service or replace.
rivets, weak, damaged or incorrect
shoe retracting springs, loose or
damaged shoe retainer pins, springs
and clips, and grooved backing plate
ledges.
2. Squeal or Squeak - Brakes not 1. Wheel cover attachment. 1. Seat covers with a rubber mallet.
applied. Service flanges or replace cover.
2. Improper machining of drum, 2. Replace drum.
causing interference with backing
plate or shoe.
3. Bent or warped backing plate 3. Service or replace. or shoe.
4. Loose wheel attaching lug nuts. 4. Tighten to correct torque. Replace
wheel if stud holes are damaged.
5. Other pans to check: 5. Inspect, service, replace as required.
- Loose or extra pans in drum.
- Drum brake adjustment too tight
causing lining to glaze.
- Drum brake shoe retracting
springs weak, damaged or wrong
parts.
- Drum brakes - grooved backing
plate ledges.
- Improper positioning of shoe
in caliper.
- Outside diameter or rotor rubbing
caliper housing.
- Lack of correct lubricant on disc
brake caliper slides (if
applicable).
- Improper installation of disc brake
anti-rattle clip.
- Worn, damaged, or insufficiently
lubricated wheel bearings.
3. Rattle, Clunk, Knock, Click - 1. Caliper support pins. 1. Tighten or replace.
Series of sharp, short sounds 2. Pin bushings. 2. Replace as necessary.
in quick succession. 3. Pin teflon sleeve. 3. Replace as necessary.
4. Inner/outer shoe clips. 4. Service or replace as necessary.
Ref. Technical Service Bulletin No.
80-11-2-S, dated 8/4/80.
5. Caliper hold-down spring (front 5. Service or replace as necessary
wheel drive vehicles only).
6. Dust shield. 6. Service as necessary.
7. Grease shield (front wheel drive 7. Service as necessary.
vehicles only).
8. Outer disc brake shoe locating 8. Check and reseat if necessary.
buttons not seated in caliper holes.
9. Drum brakes - shoes binding at 9. Lubricate ledges.
backing plate ledges.
10. Drum brakes - backing plate 10. Replace backing plate and lubricate.
ledges worn.
11. Stones or foreign material trapped 11. Remove.
inside wheel covers.
12. Loose grease cap. 12. Service or replace.
4. Grind - A loud, harsh rubbing 1. Bound caliper and/or brake shoes. 1a. For rear wheel drive vehicles, see
noise. TSB 81-5, dated 3/16/81,
Article 3727S.
1b. On front wheel drive vehicles, hand
sand corrosion from knuckle surface
where it touches brake shoe.
2. Contaminated linings. 2. Remove lining contamination as necessary.
3. Worn front or rear brake linings 3. Replace linings and refinish or
or rear drum. replace drums.
4. Wheel bearings not lubricated 4. Lubricate and replace bearings and
(verify noise is coming from seals as necessary. Hub nut must
bearings). also be replaced and staked on front
wheel vehicles.
5. Rear brake shoes - binding at 5. Lubricate or replace as necessary.
backing plate ledges.
6. Caliper to wheel or rotor 6. Replace as required.
interference.
7. Other pans to check: 7. Replace.
-Warped or bent splash shield.
-Warped or bent backing plate.
-Cracked drum.
-Cracked rotor.
8. Tires rubbing against chassis or 8. Inspect and service. body.
9. Rotor to spindle interference. 9. Replace as required.
5. Roughness - An unsmooth 1. Corrosion/rust build-up on rotor 1. Peform 5-10 moderate brake stops.
feeling while braking in neutral surfaces. Do not sand rotors. If roughness
evidenced by a pulsating brake persists, replace rotor(s). Black
pedal. discoloration on rotors is caused by
semi-metallic linings and should not
be removed. Rust that does not
cause pulsation should not be
removed.
2. Rotor thickness variation. 2. Replace rotor.
3. Rear brake roughness. 3. Attempt stopping the vehicle using
the parking brake. If roughness is
present, check drums for excessive
wear or runout. Refinish or replace
as necessary.
4. Wheel bearings mis-adjusted. 4. Inspect and adjust bearing setting as necessary.
5. Wheel-tire imbalance. 5. Verify and service as necessary. Refer to TSB No.82-16.
6. Drivetrain imbalance. 6. Attempt stopping vehicle in neutral
transmission position. If roughness
is gone, drivetrain should be
inspected. Refer to TSB No. 81-19A.
OTHER APPLICABLE ARTICLES: 82-21-5
WARRANTY STATUS: "INFORMATION ONLY"