Front Rail End Replacement Front Crush Cap Replacement

Important: The redesigned frame of the C/K pickup incorporates hydroformed technology. The C/K pickup utilizing high-strength, low-alloy steel in the middle and rear sections. There is a replaceable, hydroformed, energy absorbing crush cap at the front of the frame (1500 series only). The rear section is replaceable at the factory seams as a 1 piece assembly.

1. Remove all of the related panels and the components.

Important: If the crush cap (1) is bent or damaged in any way you must replace the crush cap.

2. Visually inspect the damage. Use 3 dimensional measuring in order to restore all of the damage rearward of the crush cap (1) to the factory specifications.




Important: Use caution not to damage the rail.

3. Remove the core support mounting bracket (2).
4. Locate the brake line attachment hole (1) on the top of the rail. Measure forward 155 mm (6 1/8 in). This is the cut line (2).
5. Scribe a line 360 degrees around the frame rail.

Important: Use caution to not damage the cross tube

6. Remove the crush cap at the cut-line and the forward edge of the cross tube.



7. Grind the remaining weld off of the cross tube (1) where you removed the damaged crush cap.

1. Drill 4 plug weld holes (2 at the top and 2 at the bottom), 13 mm (1/2 in) from the cut line and 50 mm (2 in) apart on the existing frame rail (1).
2. Prepare all of the bare metal surfaces with a suitable weld through primer.




Important: The replacement bumper bracket (2) is a bolt-on component that must be ordered separately.

Important: Retain a gap of 1½ times the metal thickness at the butt joint when attaching the service part to the vehicle (1).

3. Install and position the replacement crush cap using 3 dimensional measuring.
4. Tack weld the part into position at the initial plug weld holes.
5. Inspect the service part for proper dimensions.
6. Stitch weld along the entire sectioning joint. Make 25 mm (1 in) welds along the seam with 25 mm (1 in) gaps between.
7. Complete the stitch weld.
8. Clean and prepare the welded surfaces.

Important: Prior to refinishing, refer to GM P/N 4901MD-98 Refinish Manual for recommended products.

9. Apply approved anti-corrosion primer.
10. Position the new core support mounting bracket. Weld the bracket in place according to the specified dimensions.
11. Apply the sealers.
12. Refinish the welded surfaces as necessary.
13. Replace the related panels and the components.