Sovereign L6-4.0L (1991)
Drive/Propeller Shaft: All Technical Service Bulletins
Propshaft - Vibration
47-4
Propshaft Vibration Adjustment Procedure
MODEL
90-91 Sedan
DATE 5/91
ISSUE:
Adjustment procedure for complaints of propshaft vibration at 30-50 mph on 90-91 MY sedans up to VIN 646879.
ACTION:
At VIN 646880, a newly designed propshaft has been introduced which eliminates the vibration condition identified above.
On 1990/1991 vehicles up to VIN 646879, the only way of improving propshaft vibration is through an adjustment procedure which is detailed below.
Do not replace propshafts or other driveline components to correct propshaft vibration. Do not switch propshafts from one car to another.
Correct by adjusting:
^
Rear engine mounting.
^
Center bearing assembly.
^
Rotational orientation of the propshaft.
INITIAL CHECKS:
^
Road test (with the customer in the vehicle) to verify the complaint. Note road speed at which vibration occurs. Re-test by coasting in Neutral down
through the noted speed range. If the vibration is still present, then the propshaft is the cause.
^
Centralize the engine on it's front mounts. Make sure that the transmission output flange is in the center of the propshaft tunnel.
^
Adjust the rear engine mounting crossmember to centralize the transmission mounting stud with the inspection hole in the crossmember.
^
Check all drive flange and drivetrain mounting bolts for proper torque.
FIG. 1
^
Check which type of propshaft is installed, (fig. 1). (both are acceptable).
