Noise/Rattle from Rear of Vehicle While Driving (Replace Rear Backing Plate Bolts)

Some customers may comment on a rattle noise coming from the rear of the vehicle while driving.

This condition may be caused by the rear backing plate bolts being under torqued.

Visually and physically inspect the rear backing plate bolts for looseness. The bolts in questions will be black in color.

Follow one of the two service procedures below, depending on if the vehicle has a V6 or a V8 engine.

Service Procedure for V6 Engine (VIN K - RPO L36) and V8 Engines (VIN G - RPO LS1) Without NW9 Traction Control

1. Ensure that the park brake is released.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information (SI2000 Document ID # 668434).
3. Remove the rear tire and wheel assembly. Refer to Tire and Wheel Removal and Installation in Tires and Wheels (SI2000 Document ID # 675692).




Notice: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from its mount and the hydraulic flexible brake hose is still connected. Failure to support the caliper in this manner will cause the flexible brake hose to bear the weight of the caliper which may cause damage to the brake hose and in turn may cause a brake fluid leak.

4. Remove the brake caliper and the caliper mounting bracket (2) as an assembly from the rear axle (3) and support the assembly with heavy mechanic's wire, or equivalent. Ensure that there is no tension on the hydraulic brake flexible hose. Do NOT disconnect the hydraulic brake flexible hose from the caliper.
5. Remove the brake rotor (4). Do not force the rotor off. If the rotor is difficult to remove, ease it off by gently rotating it as you pull it outward.
6. Remove the four bolts and nuts retaining the backing plate to the axle housing flange and discard the old nuts and bolts.
7. Apply threadlocker, P/N 12345493 (in Canada, use P/N 10953488), on the new bolts, P/N 11516943, and install the bolts into the axle housing flange to the backing plate.

Important: You must hold the head of the bolt while tightening the nut.

8. Install the new nuts, P/N 11514603.

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

9. Install the brake rotor to the axle shaft flange.



10. Install the brake caliper (2) and the brake caliper bracket as an assembly to the rear axle (3).
11. Apply threadlocker, P/N 12345493 (in Canada, use P/N 10953488), to the bolt threads.

Tighten
Tighten the caliper bracket mounting bolts (3) to 100 N·m(74  lb  ft).

12. Install the tire and wheel assembly. Refer to Tire and Wheel Removal and Installation in Tires and Wheels (SI2000 Document ID # 675692).
13. Lower the vehicle.

Service Procedure for V8 Engine (VIN G - RPO LS1 with NW9 Traction Control)

1. Ensure that the park brake is released.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information (SI2000 Document ID # 668434).
3. Remove the rear tire and wheel assembly. Refer to Tire and Wheel Removal and Installation in Tires and Wheels (SI2000 Document ID # 675692).




Notice: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from its mount and the hydraulic flexible brake hose is still connected. Failure to support the caliper in this manner will cause the flexible brake hose to bear the weight of the caliper which may cause damage to the brake hose and in turn may cause a brake fluid leak.

4. Remove the brake caliper and the caliper mounting bracket (2) as an assembly from the rear axle (3) and support the assembly with heavy mechanic's wire, or equivalent. Ensure that there is no tension on the hydraulic brake flexible hose. Do NOT disconnect the hydraulic brake flexible hose from the caliper.
5. Remove the brake rotor (4). Do not force the rotor off. If the rotor is difficult to remove, ease it off by gently rotating it as you pull it outward.
6. Remove the rear axle housing cover. Refer to Rear Axle Housing Cover and Gasket Replacement in the Rear Drive Axle sub-section (SI2000 Document ID # 678551).



7. Remove the pinion gear shaft lock bolt (5) from the differential case.
8. Remove the pinion gear shaft from the differential case.
9. Push the flanged end of the axle shaft into the rear axle housing in order to access the rear axle shaft lock (1).
10. Remove the rear axle shaft lock (1).
11. Remove the rear axle shaft from the rear axle housing.
12. Remove the four bolts and nuts retaining the backing plate to the axle housing flange and discard the old nuts and bolts.
13. Apply threadlocker, P/N 12345493 (in Canada, use P/N 10953488), to the new bolts, P/N 11516943, and install the bolts into the axle housing flange to the backing plate.

Important: You must hold the head of the bolt while tightening the nut.

14. Install the new nuts, P/N 11514603.

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

15. Install the axle shafts into the axle housing.
16. Install the rear axle shaft lock.
17. Push the axle shaft outward so that the rear axle shaft lock seats in the counterbore of the differential side gear.
18. Install the pinion gear shaft through the following components:

•	The differential case

•	The pinion gear thrust washers

•	The pinion gears. Align the hole in the pinion gear shaft with the rear axle shaft lock bolt/screw hole in the differential case.

19. Thoroughly clean the threads of the pinion gear shaft lock bolt and apply threadlocker, P/N 12345493 (in Canada, use P/N 10953488), to the threads.
20. Install the pinion gear shaft lock bolt .

Tighten
Tighten the differential pinion gear shaft lock bolt to 36 N·m(27 lb ft).

21. Install the rear axle housing cover. Refer to Rear Axle Housing Cover and Gasket Replacement in the Rear Drive Axle sub-section (SI2000 Document ID # 678551).
22. Refill the rear axle with lubricant. Refer to Lubricant Level Check (SI2000 Document ID # 678548).
23. Install the brake rotor to the axle shaft flange.



24. Install the brake caliper (2) and the brake caliper bracket as an assembly to the rear axle (3).
25. Apply threadlocker, P/N 12345493 (in Canada, use P/N 10953488), to the bolt threads.

Tighten
Tighten the caliper bracket mounting bolts (3) to 100 N·m(74 lb ft).

26. Install the tire and wheel assembly. Refer to Tire and Wheel Removal and Installation in Tires and Wheels (SI2000 Document ID # 675692).
27. Lower the vehicle.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: