Restore roof damage with these steps

Sept. 2, 2019
Considering the relative low number of rollovers and other accidents that cause roof damage, many repairers may not have a lot of experience performing a repair here. It’s time for a change.

When consumers think of serious collision damage, many no doubt picture high-speed rollovers. Little wonder. National Highway Transportation Safety Administration (NHTSA) statistics show rollovers account for more than a third of overall traffic fatalities—22 percent of deaths in passenger cars, 45 percent in pickups and 61 percent in SUVs. Making these numbers even more significant is the fact that NHTSA data also show rollovers account for just 3.1 percent of all vehicle accidents (Note: It’s important to remember that 69 percent of these fatalities were not wearing seatbelts.)

Over the years, manufacturers have worked hard to develop safety and stabilization programs to prevent these kinds of accidents. They’ve also worked hard developing roof structures that supply extra protection to motorists. When these structures are damaged, collision repairers must work just as hard restoring today’s more sophisticated roof parts to safe, pre-accident condition.

(Photo courtesy of GM Media) Unless you see a lot of vehicles needing moonroof work or that have been in rollover accidents, you may not have performed many roof replacements and other repairs.

Considering the relative low number of rollovers and other accidents that cause roof damage, many repairers may not have a lot of experience performing a repair here. It’s time for a change. Build up your knowledge of roof work by referring to the following instructions, supplied by General Motors, for roof repairs on SUVs, pickups and midsize cars.

2019 GMC Yukon

Note: Center Pillar Outer Panel Reinforcement Replacement and Roof Replacement are both included here since they often must be repaired in tandem.

Center Pillar Outer Panel Reinforcement Replacement

Removal Procedure

Warning: Refer to GM’s Approved Equipment for Collision Repair Warning document.

Warning: Refer to GM’s Foam Sound Deadeners Warning document.

Warning: Refer to GM’s Battery Disconnect Warning document.

Note: The center pillar outer panel reinforcement is made of Ultra High Strength Steel. Sectioning, or repair of Ultra High Strength Steel is not recommended. It should be replaced as a complete assembly at factory locations. Refer to GM’s Ultra High Strength Steel document.

Note: This procedure was developed to allow access for the complete replacement of the center pillar outer panel reinforcement without removing the roof panel. There are sectioning procedures available for various locations of the body side outer panel. The location should be chosen based on the extent of the damage to the vehicle and other inner reinforcements that need to be replaced. Sectioning should be performed only in the recommended areas. Failure to do so may compromise the structural integrity of the vehicle. Refer to other service procedures for additional sectioning locations.

  1. Disable the SIR System and then disconnect the negative battery cable. Refer to GM’s SIR Disabling and Enabling document.
  2. Remove all related panels and components.
  3. Repair as much of the damaged area as possible. Refer to GM’s Dimensions - Body document.
  4. Remove the sealers and anti-corrosion materials from the repair area, as necessary. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  5. Perform additional sectioning procedures for short wheelbase as necessary. Refer to the following procedures:
    • Front Hinge Pillar Sectioning
    • Center Pillar Sectioning
    • Rear Pillar Sectioning
    • Rocker Outer Panel Sectioning
  6. Perform additional sectioning procedures for long wheelbase as necessary. Refer to the following procedures:
    • Front Hinge Pillar Sectioning
    • Center Pillar Sectioning
    • Rear Pillar Sectioning
    • Rocker Outer Panel Sectioning
  7. Remove body side outer as necessary for access to the center pillar outer panel reinforcement.

Note: Record the number and location of welds for installation of the service assembly.

  1. Remove all necessary factory welds.
  2. Remove the damaged center pillar reinforcement.

Installation Procedure

  1. Clean and prepare all mating surfaces, as necessary for welding.
  2. Align the center pillar reinforcement.
  3. Drill 8 mm (5/16 in.) for plug welding along the top and bottom of the center pillar reinforcement from the original panel.
  4. Position the center pillar reinforcement on the vehicle using 3-dimensional measuring equipment.
  5. Verify the fit of the center pillar reinforcement.
  6. Clamp the center pillar reinforcement into position.
  7. Weld at the original weld locations.
  8. Complete body side outer sectioning as necessary.
  9. Apply the sealers and anti-corrosion materials to the repair area, as necessary. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  10. Paint the repaired area. Refer to GM’s Basecoat/Clearcoat Paint Systems document.
  11. Install all related panels and components.
  12. Enable the SIR system and then connect the negative battery cable. Refer to GM’s SIR Disabling and Enabling document.
(Photo courtesy of GM Media) Replacing the roof panel of a damaged vehicle often can accompany doing other work, such as repairing the center pillars.

Roof Outer Panel Replacement

Removal Procedure

Warning: Refer to GM’s Approved Equipment for Collision Repair Warning document.

Warning: Refer to GM’s Glass and Sheet Metal Handling Warning document.

Warning: Refer to GM’s Battery Disconnect Warning document.

  1. Disable the SIR system. Refer to GM’s SIR Disabling and Enabling document.
  2. Remove all related panels and components.
  3. Repair as much of the damage as possible to factory specifications.

    Warning: Refer to GM’s Foam Sound Deadeners Warning document.
  1. Note the location and remove the sealers and anti-corrosion materials from the repair area, as necessary. Refer to GM’s Anti-Corrosion Treatment and Repair document.

    Note: Do not damage any inner panels or reinforcements.
  1. Locate and drill out all factory welds. Note the number and location of the welds for installation of the roof panel.
  2. Remove the damaged roof panel.

Installation Procedure

  1. Prepare all attachment surfaces as necessary for welding.
  2. Apply GM–approved Weld-Thru Coating or equivalent to all mating surfaces. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  3. Position the roof panel.
  4. Weld accordingly.
  5. Clean and prepare all welded surfaces.
  6. Apply the sealers and anti-corrosion materials to the repair area, as necessary. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  7. Paint the repair area. Refer to GM’s Basecoat/Clearcoat Paint Systems document.
  8. Install all related panels and components.
  9. Connect the negative battery cable. Refer to GM’s Battery Negative Cable Disconnection and Connection document.
  10. Enable the SIR system. Refer to GM’s SIR Disabling and Enabling document.

2019 GMC Canyon Pickup

Roof Outer Panel Replacement (Adhesive Weld Bonding Procedure)

Removal Procedure

Warning: Refer to GM’s Approved Equipment for Collision Repair Warning document.

Note: When replacing panels that involve servicing of stationary windows, refer to GM’s Adhesive Installation of Windshields and Adhesive Installation of Rear Windows document, before performing any priming or refinishing.

  1. Disable the SIR system. Refer to GM’s SIR Disabling and Enabling document.
  2. Disconnect the negative battery cable. Refer to GM’s Battery Negative Cable Disconnection and Connection document.
  3. Remove all related panels and components.
  4. Repair as much of the damage as possible, to factory specifications. Refer to GM’s Dimensions – Body document.
  5. Note the location and remove the sealers and anti-corrosion materials from the repair area, as necessary. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  6. Remove the windshield and rear windshield. Refer to GM’s Windshield Replacement document.
  7. Locate and drill out all factory welds. Note the number and location of welds for installation of the roof panel.
  8. With an assistant, remove the roof panel.

Installation Procedure

Note: Before you begin the repair, refer to GM’s Metal Panel Bonding document for proper adhesive preparations and general information.

  1. Grind the surface of the roof panel mating flanges to bare steel with an 80 grit Roloc disc. Do not damage the corners or thin the metal during the grinding process.
  2. Grind the mating flanges of the service roof panel with an 80 grit Roloc disc to remove the E-coating. Do not damage the corners or thin the metal during the grinding operation.
  3. Clean all mating surfaces, as necessary and test fit the replacement roof panel.

Note: Do not allow the adhesive to cure prior to installing the service side panel.

  1. Apply a 3–6 mm (1/8–1/4 in.) bead of Impact Resistant metal panel bonding adhesive to both mating surfaces.
  2. Using a small acid brush, spread a coat of adhesive to both mating surfaces. Cover all bare metal to ensure corrosion protection.
  3. Apply a 9–13 mm (3/8–1/2 in.) bead of metal panel bonding adhesive to the mating surface of the service roof panel.
  1. With the aid of an assistant, position the roof panel to the body.
  2. Clamp the service roof panel into position.
  3. Weld the flange of the windshield opening and the rear window opening with resistance spot welding through the adhesive.
  4. Using lacquer thinner remove the excess adhesive from the bed side panel area.
  5. Apply the sealers and anti-corrosion materials to the repair area, as necessary. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  6. Paint the repair area. Refer to GM’s Basecoat/Clearcoat Paint Systems document.
  7. Install the windshield. Refer to GM’s Windshield Replacement document.
  8. Install the rear window. Refer to GM’s Rear Window Replacement document.
  9. Install all related panels and components.
  10. Connect the negative battery cable. Refer to GM’s Battery Negative Cable Disconnection and Connection document.
  11. Enable the SIR system. Refer to GM’s SIR Disabling and Enabling document.
(Photo courtesy of GM Media) Replacing the roof panel is no longer simply a matter of pulling off the old part and bolting on a new one. New vehicles like the 2019 GMC Canyon require adhesive weld bonding.

2019 Chevrolet Malibu

Roof Outer Panel Replacement

Removal Procedure

Warning: Refer to GM’s Approved Equipment for Collision Repair Warning document.

Warning: Refer to GM’s Glass and Sheet Metal Handling Warning document.

Caution: Refer to GM’s Collision Repair Anchoring Caution document.

  1. Disable the SIR system. Refer to GM’s SIR Disabling and Enabling document.
  2. Disconnect the negative battery cable. Refer to GM’s Battery Negative Cable Disconnection and Connection document.
  3. Remove all related panels and components.
  4. Visually inspect the damage. Repair as much of the damage as possible, prior to replacing the damaged parts.
  5. Remove the sealers and anti-corrosion materials from the repair area. Refer to GM’s Anti-Corrosion Treatment and Repair document.

Note: Do not damage or cut attaching panels and reinforcements. Refer to GM’s Structure Identification document.

Note: Record the number and location of the original welds for installation of the service assembly.

  1. Remove all factory welds from the body rear end panel.
  2. Remove the sealant from the roof outer panel channel.
  3. Cut the roof frame adhesive with appropriate tool.
  4. Use a cut off wheel or equivalent to grind out the laser welded seam.

Note: If impact resistant adhesive is present remove and replace as necessary.

  1. Remove the damaged roof from the vehicle.

Installation Procedure

Note: Squeeze Type Resistance Spot Welds equivalent to the factory spot welds are recommended. If access to use Squeeze Type Resistance Spot Welds is not possible, MIG/MAG plug welds may be used, to replace those specific welds.

Note: MIG Brazing Welds equivalent to the factory brazing welds are recommended.

  1. Clean and prepare all attaching surfaces as necessary for welding.
  2. Apply GM-approved Weld-Thru Coating or equivalent to all matting surfaces. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  3. Apply Fusor super flexible anti-flutter foam fast set, or equivalent to the roof bows, in the locations noted from the original panel.
  4. Position the roof outer panel to the vehicle.
  5. Verify the fit of the roof outer panel.
  6. Clamp the body rear end panel into position.
  7. Spot weld the front and rear header panels.
  8. Stitch weld the roof outer panel to the side rails. To create a solid weld with minimum heat distortion, make 25 mm (1 in.) stitch welds along the seam with 25 mm (1 in.) gaps between them. Then go back and complete the stitch weld.
  9. Apply the sealers and anti-corrosion materials to the repair area, as necessary. Refer to GM’s Anti-Corrosion Treatment and Repair document.
  10. Use a high-quality seam sealer to fill the gap between the outer roof panel and the bodyside roof rail. Follow the manufacturer’s instructions.
  11. Paint the repair area. Refer to GM’s Basecoat/Clearcoat Paint Systems document.
  12. Install all related panels and components.
  13. Connect the negative battery cable. Refer to GM’s Battery Negative Cable Disconnection and Connection document.
  14. Enable the SIR system. Refer to GM’s SIR Disabling and Enabling document.

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