Suspension - Noise From Rear
90pontiac06Bulletin Number: 89-3-17B
Reference Number: 903401R
Publish Date: 3/90
Subject: REAR SUSPENSION NOISE (DIAGNOSIS AND PROCEDURES)
Models
Affected: 1987-89 BONNEVILLE MODELS
This bulletin cancels and replaces bulletin 89-3-17A issued 12/89. This bulletin has been revised to update parts information under "straight rate spring".
Rear suspension noise on some 1987 through 1989 Bonneville models can be caused by the following:
Spring Contact With Body Flange
This condition can be verified by visual inspection for any signs of contact between the coil spring and the body flange. If this condition exists, the following should be done.
^ The body flange sheet metal should be carefully repositioned to maximize clearance. Apply paint and/or rustproofing material as needed to prevent corrosion.
^ Inspect the coil springs for proper position. If necessary, position the springs as shown in the illustration below, taken from the 1989 Service Manual, so that the ends of the spring pigtails are positioned outboard. Note that this orientation is different than that shown in the 1987 thru 1988 Chassis Service Manuals.
Top spring coils contact each other 1987 (cars without Electronic Level Control)
^ This condition can occur in the variable rate design springs used on 1987 Bonneville cars without Electronic Level Control. If this condition is suspected, it can be verified by installing insulating material (heater hose or equivalent) to the top coils and test driving. If the noise is eliminated with the insulating material, the rear coil springs should be replaced with the appropriate springs from GMSPO.
^ If the suspension noise is determined to be caused by the rear variable rate coil springs, and the noise cannot be eliminated by any of the above methods (including replacing the original variable rate rear coil springs with new variable rate rear coil springs), the variable rate springs may be replaced with straight rate springs (both sides must be replaced) according to the following table: