Tools Required

J 42058 Frame Adapter Clamp

Important: Save any and all brackets, mounting studs, and accessories for transfer to the new rear compartment panel.

1. Remove all panels and components to gain access to the rear impact bar. This includes the following components:

•	Rear bumper cover

•	Energy absorber

•

Mufflers

1.1.	Disconnect exhaust at the bolted joint just forward of the rear axle.

1.2.	From inside the vehicle remove trim panels.

1.3.	Pull back the carpeting inside the rear compartment area.

Notice: The frame rails and bumper impact bars must be serviced as required, and returned to three-dimensional coordinates before any SMC repairs are attempted.

2. Visually inspect and restore as much of the damage as possible to specifications using three-dimensional measuring procedures. Use J 42058 if pulling and straightening of the vehicle are required.
3. Remove or reposition wiring as necessary to avoid being damaged.




Notice: Do not cut the rails when cutting windows in the rear compartment panel.

Important: The top and bottom welded edges, as well as the outer rail welds, are accessible from outside the vehicle.

4. Using a die grinder or equivalent, cut the MIG welds attaching the rear impact bar to the frame rails.



5. Cut the welds around the perimeter of the frame rail (fishmouth) ends.
6. Cut the welds favoring the impact bar side of the joint. Do not cut into the frame rails.
7. To gain access to the inner rail welds, modify the rear wall of the SMC rear compartment panel in the following manner:

•	Save the cutouts for re-installation.

•	From inside the vehicle locate, mark, and cut out 'windows' in the rear compartment panel.




8. The 'windows' provide access to inner MIG welds attaching the impact bar to the rails.

Notice: Protect the interior of the vehicle before cutting or grinding the SMC body or the bumper impact bar.

9. Cut the remaining welds around the perimeter of the impact bar, favoring the impact bar side of the joint.



10. If necessary, apply heat, then pry apart to separate the impact bar from rear panel.

Important: Do not install the 'windows' in rear compartment yet; welding access is necessary for installing the replacement impact bar.

11. With the rear bumper impact bar removed, repair any cracks in the SMC from outside the vehicle.

1. Straighten and deburr the rail ends as necessary to allow the service bumper impact bar to fit the rail ends properly.
2. Remove any adhesive which is cracked or broken loose from the rails or the rear compartment panel.
3. Remove the primer from the areas to be MIG welded by sanding with 80-grit paper on a Dual-Action (DA) sander. Do not use a grinder to remove the primer.
4. Prepare all bare metal surfaces and apply weld-through primer as necessary. Be sure to apply primer to the inside of the fishmouth area also.



5. Position the bumper impact bar using three-dimensional measuring equipment and weld accordingly.

5.1.	Stitch weld around the fishmouth joint.

5.2.	Make 40 mm (1 in) MIG welds along the top, bottom, and outer sides of the joint. This will create a solid weld joint with minimal heat distortion.




6. Clean and prepare all welded surfaces using 3M's Scotch-Brite Clean-N-Strip Discs (disc P/N 07460, mandrel P/N 07491), or equivalent.

Notice: Do not top coat the top surface of the impact bar where it is to be bonded to the rear compartment panel. The bonding area must remain a primer-only surface.

7. Prime all bare metal surfaces with two-part catalyzed primer. Refer to GM P/N 4901M-D Refinish Manual. Do not top-coat any bonding surfaces.
8. From outside the vehicle, apply 50 mm (2 in) wide tape over the 'windows' cut in the rear compartment panel.

Important: Use US Chemical and Plastics 82014B System 2000 Structural Adhesive, a PLIOGRIP® Adhesive manufactured by Ashland Chemical Company, or equivalent. Note the 9 minute working time and 1 hour cure time.

9. Apply adhesive to the inside of the tape backer.
10. Install the previously cut-out pieces in their original locations.
11. Apply a thin coat of Goodwrench Structural Bonding Epoxy (P/N 1234526), or equivalent, to the entire repair area extending across the cut lines, using tacky mesh tape or an equivalent reinforcement matting.

•	Apply enough bonding epoxy to fully 'wet out' reinforcement matting.

•	Allow to cure as necessary.

12. Scuff all bonding surfaces to ensure proper adhesion.
13. Clean and prepare all bonding surfaces as necessary.



14. Apply a bead of urethane adhesive to bond the impact bar to the rear compartment. This is a structural bond, and care must be used to ensure that the adhesive fills the gap adequately.
15. Finish and feather-edge the repair areas as necessary to resemble OEM.
16. Prime the SMC repair areas with a suitable primer.
17. Apply appropriate sealers.
18. Apply top-coat over all repaired areas. Refer to paint manufacturer's recommendations. Do not combine paint systems.
19. Install all related panels and components.