If the vehicle has been involved in a collision check for Stress Crack (1) and/or Spotted Stress (2) in the frame or for signs of damage.

A misaligned underbody rail may have moved forward from, up or down from, or to the side of where the rail should be. Inspect the rails for all of these possibilities.

The easiest way to check alignment is with tramming gauges and with universal measuring systems made for this purpose. Detailed instructions are normally supplied with the equipment at the time of purchase. Therefore, instructions for equipment usage are not given in this manual.

Whether alignment is made with or without gauges, the vehicle must be parked on a level section of the floor.

Certain conditions call for preliminary inspections before actually examining the underbody structure.

A visual inspection of the top and the bottom flanges of each rail may reveal the specific area where sag or buckle exists. In the case of sag, wrinkles may appear on the top of the upper flange. Wrinkles on the bottom of the lower flange are definite evidence of buckle.