Knocking Noise from Rear of Vehicle on Aggressive Launch or Acceleration (Install Rear Suspension Crossmember Front Mount Insulators)

This bulletin is being revised to change a torque specification within the correction procedure. Please discard Corporate Bulletin Number 04-03-09-003 (Section 03 -- Suspension).

Some customers may comment on a knocking noise coming from the rear of the vehicle. This noise occurs during an aggressive launch or acceleration and will be more common on vehicles with a manual transmission.

The cause of this condition may be contact between the body and the rear suspension crossmember.

Install insulators, P/N 90447991, and new bolts, P/N 92038482, between the body and the rear suspension crossmember using the procedure listed below.

Important: Only remove the bolts from one side of the suspension crossmember at a time, and DO NOT loosen the opposite side, until the insulator is installed on the first side and all fasteners have been tightened to the specified torque setting.




1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in the General Information sub-section of the Service Manual. Position rear hoist arms as shown.



2. Support the rear suspension crossmember just under the brace (2) using an adjustable jack stand.
3. Remove the 3 brace to underbody bolts (3).
4. Remove the front mount bolt (4) attaching the rear suspension crossmember to the underbody.
5. Lower the jack stand slightly to allow clearance between the crossmember and the underbody.

Important: When installing the insulator onto the crossmember front mount bushing, face the corrugated side upwards, so it bears against the underbody.

6. Install the insulator (1) between the underbody and the upper part of the crossmember, ensuring to seat the insulator firmly onto the center of the crossmember front mount bushing.
7. Raise the crossmember using the jack stand until it is pressing firmly against the underbody.
8. With the jack stand still in position to support the crossmember, install the new front mount bolt and the 3 brace to underbody bolts.

Tighten
Tighten the crossmember front mount bolt to 125N·m(92 lb ft). Use J 45059 Torque Angle Meter in order to tighten the bolt an additional 40 degrees.

Tighten
Tighten the brace bolts to 65N·m(48 lb ft).

9. Remove the jack stand.
10. Repeat steps 2 to 9 for the opposite side.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use:

*This is a unique labor operation number for use only with this bulletin. This number will not be published in the Labor Time Guide.