For 1990-2009 cars only
The following are 2 common types of cracks:
| • | The straight crack, normally starts from the edge of a flange. The straight crack will go across the flange and through the web section of a rail, and continue through the other flange. The straight crack may result from high concentrations of stress in small areas of the frame, excessive bending movement, and torsional loading. Refer to Minimizing Frame Service Description . |
| • | Sunburst cracks radiate outward from a hole in the web area of a rail or crossmember. Sunburst cracks are caused by high loads being applied at a mounting bracket or crossmember which is not properly attached to the rail. |
Repair cracks separately when cracks occur the rail and reinforcement at a particular area of the frame. The flanges react independently to prevent localized stress concentration. Use a copper spacer between the flanges of cracked base rail flanges and reinforcement flanges.
Use a weld bead to provide a good, smooth radius when repairing crossmember mounting flange cracks. Replace any damaged crossmember.
Align the frame and level the rails before repairing the frame:
- Remove any equipment that interferes with access to the crack.
- Locate the extreme end of the crack and drill a 3 mm (0.12 in) hole.
- V grind the entire length of the crack from the starting point to the 3 mm (0.12 in) hole at the extreme end.
- Remove the protective coating on the frame in the area of the repair. Open the bottom of the crack 2 mm (1/16 in) to allow good penetration of the weld. Use a hacksaw blade.
- Weld the frame with the proper electrode and the proper welding techniques. Refer to Welding Description .
- Grind the weld smoothly on the inside and the outside of the rail or the crossmember. Eliminate the weld buildup or notches on the edge of the flange. Apply the coating of protective material.
