Sectioning procedures have been developed to simplify repair to the lower rails, providing the majority of the damage can be returned to factory specifications. This allows the damaged front section to be replaced without performing full rail replacement. Bumper mounting brackets can be serviced separately.

1. Remove all related panels and components as necessary.
2. Visually inspect and restore as much of the damage as possible to factory specifications.

Important: Removal of the cradle and powertrain is not necessary when performing this procedure.

3. Locate the cut location on the damaged front rail, use the front cross-member cagenut slot for reference.



4. Measure 335 mm (13 3/8 in) forward from the front edge of the slot. This is the cut location on the damaged part.
5. use a straight edge to scribe a line around the rail.
6. Cut and discard the damaged portion of the rail.
7. Cut and remove approximately 5 mm (¼ in) of the outboard and downward turned flanges of the original rail on the rail end.



8. Cut a 5 mm (¼ in) approximately 5 mm (¼ in) along the corners of the original rail to create a 5 mm (¼ in) tab for the service part to slide over.



9. Slightly bend the tabs inward to allow the replacement lower rail section to fit over the original rail.
10. Apply weld-through coating to all bare metal areas as necessary before fitting service part.

1. Locate the cut location on the service part, using the front crossmember cagenut slot for reference.
2. Measure 330 mm (13- 1/8 in) forward from the front edge of the slot. This will be the cut location for the service part.
3. Scribe a line around the rail with a straight edge.
4. Cut and remove the front portion of the rail.
5. Discard the unused rear portion of the service part.
6. Clean burrs on the inside of the rail.
7. Apply weld-thru primer to bare metal surfaces as necessary.

1. Position the modified service part over the tabs of the original rail, allow 5 mm (¼ in) of overlap.
2. Clamp in place.
3. Check fit using three-dimensional measuring equipment.
4. Stitch weld along the entire sectioning joint.
5. Make 25 mm (1 in) welds along the seam with 25 mm (1 in) gaps between them.
6. Complete the stitch weld to create a solid joint with minimal heat distortion.
7. Clean and prepare welded surfaces.

Important: Prior to refinishing, refer to GM P/N 4901MD-99 Refinish Manual for recommended products.

8. Apply two-part catalyzed primer.
9. Apply sealers and anti-corrosion protection materials as necessary. Do not combine paint systems. Refer to paint manufacturer's recommendations.
10. Install all related panels and components.