Seville V8-273 4.5L (1989)
Technical Service Bulletin # 58975
Date: 890201
Brakes - Pulsation Diagnosis and Repair
Bulletin No.
T-89-75
File in Group
5
Number
32
Corp.Ref.No.
805006
Date
Feb. 1989
SUBJECT:
BRAKE PULSATION AND ON-CAR BRAKE ROTOR TURNING
MODELS AFFECTED:
1985-1989 DE VILLES AND FLEETWOODS 1986-1989 ELDORADOS AND SEVILLES 1987-1989 ALLANTES
1982-1988 CIMARRONS 1985-1989 FLEETWOODS AND BROUGHAMS
This bulletin discusses brake pulsation diagnosis and repair. Information is provided on a new caliper mounting bolt and sleeve bushing assembly for
selected models and new equipment available for on-car rotor finishing.
Conditions and Causes
FIGURE 1 - HOLE WHEEL NUT TIGHTENING SEQUENCE
CONDITION
Some vehicles may exhibit a pulsating or vibrating condition (roughness) when the brakes are applied. This bulletin specifically addresses pulsation
resulting from disc brake rotor thickness variation. It should be recognized that vibration perceived by the customer may be induced by rear brakes or
may also be due to vibration from other components such as drivetrain, tires, and/or road surface conditions.
CAUSES
One possible cause of rear drum brake pulsation is an out-of-round condition (radial run out) in a rear drum. This may occur during manufacture,
however, a brake drum may also be distorted if pried off, struck with a hammer, or dropped during routine brake inspection or service.
Causes of rear brake pulsation on vehicles equipped with four-wheel disc brakes are essentially the same as those described for front brake pulsation.
Front Brake Pulsations
