GM Service Manual Online
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.