Notice: Use the offset lap-joint only in the recommended areas.

Important: The offset lap-joint is used in areas that have compound angles that won't allow the service part to fit properly with an internal sleeve. In these areas use the offset overlap method which will provide for some adjustment as well as allow for cut lines that may not be completely straight.

1. Determine the location to perform the sectioning, being sure to stay within the recommended areas.
2. Cut the damaged rail accordingly.
3. Cut any additional welds as necessary.
4. Remove the damaged portion of the frame rail.
5. Measure the service rail for sectioning.

•	The overlap of the service part and the original rail can be as large as 100 mm (4 in).

•	This 100 mm (4 in) tolerance provides an area to install plug welds on the sides of the rail. It also allows for adjustment during the installation process.

6. Mark the location.
7. Cut the service rail as square as possible.



8. Modify the portion of the rail left on the vehicle to accept the service part. This is done by cutting 75 mm (3 in) slots in two opposite corners of the rail.
9. Slightly pry open the slots to accept the service part. The slots allow the service part to overlap the existing rail to form a surface for welding.



10. Drill three 8 mm (5/16 in) holes through each of the sides and two holes each in the top and bottom surface for plug welding.
11. Install the modified service part to form the offset lap-joint.
12. Align the service part using three dimensional measurements.
13. Plug weld along the overlap.
14. Stitch weld along the entire sectioning joint.

14.1.

Make 50 mm (2 in) welds on all four sides of the rail.

14.2.

Re-check the rails for proper dimensions.

14.3.

Complete the stitch welds. This will create a solid joint with minimal heat distortion.

15. Clean and prepare welded surfaces.

•	Blend in exposed side of lap joint with Goodwrench Structural Bonding Epoxy (GM part number 12345726), or equivalent.

•	Apply as necessary to achieve original appearance.

16. Prime all bare metal surfaces with two-part catalyzed primer. Refer to GM 4901M-D Refinish Manual. Do not top-coat any bonding surface.
17. Clean and prepare all bonding surfaces as necessary.