Rail Sectioning Rear Side Underbody 1/3 Rail

Caution: Refer to Approved Equipment for Collision Repair Caution in the Preface section.

Caution: Sectioning should be performed only in the recommended areas. Failure to do so may compromise the structural integrity of the vehicle and cause personal injury if the vehicle is in a collision.

1. Disable the SIR system. Refer to SIR Disabling and Enabling .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .



3. Remove all of the related panels and the components.
4. Remove the sealers and anti-corrosion materials from the repair area, as necessary. Refer to Anti-Corrosion Treatment and Repair .
5. Repair as much of the damage as possible. Refer to Dimensions - Body .



6. Locate the die mark on the outer lower surface of the rear rail, rearward of the #5 bar.




Important: Do not section the rail in any area other than the die mark location given.

7. Align a sliding square or similar tool to the line at the tip of the arrow in the die mark. Scribe a line across the rail.



8. Use the same tool to transfer this scribed line onto the sides and the weld flanges of the rail.



9. Cut at the marked location.



10. Remove the damaged component from the vehicle.



11. Drill 2 8 mm (5/16 in) plug weld holes on each of the 3 sides of the rear rail. Position the center of the holes 10 mm (3/8 in) from the cut edge.

1. Locate the die marks on the service part rear rail.



2. Align a sliding square or similar tool to the line at the tip of the arrow in the die mark and scribe a line across the rail.



3. Use the same tool to transfer this scribed line onto the sides and the weld flanges of the rail.
4. Place a mark forward, towards the rear of the arrow, 25 mm (1 in) from the scribed line on all 3 sides of the service rail.
5. Use the tool to scribe a line on all 3 sides and weld flanges of the rail.
6. Cut at the scribe line at the rear of the arrow.



7. Remove the rear portion of the rail.



8. Cut the upper outer flanges of the rear portion of the rear rail service part. Cut the flanges back to the first scribe line and remove the tabs.
9. Cut the lower radius corners of the service part back to the first scribe line and remove the small corners.
10. Bend the bottom side of the service part at the sectioning location inward slightly by aligning a vice grip flanging tool or similar tool at the first scribed line.
11. Prepare the sectioning area of the rear rail for welding.
12. Apply GM-approved weld-thru coating or equivalent to all mating surfaces. Refer to Anti-Corrosion Treatment and Repair .



13. Position the rear rail section using 3-dimensional measuring equipment. Clamp the rail section in place.



14. Tack weld the part into position.
15. Inspect the service rear rail for proper dimensions, using 3-dimensional measuring equipment.
16. Plug weld at each 8 mm (5/16 in) plug weld hole location.
17. Stitch weld along the entire sectioning joint. Make welds along the seam with 25 mm (1 in) gaps between. Weld the gaps.
18. Clean and prepare the welded surfaces.
19. Install all of the related panels and components.
20. Apply the sealers and anti-corrosion materials to the repair area, as necessary. Refer to Anti-Corrosion Treatment and Repair .
21. Paint the repaired area. Refer to Anti-Corrosion Treatment and Repair .
22. Enable the SIR system. Refer to SIR Disabling and Enabling .
23. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .