The main components of a frame are the side rails and the crossmembers. The rails carry the load and the crossmembers stabilize the rails.
Types of body misalignment are divided into the following groups:
| • | Sag |
| • | Collapse |
| • | Diamond |
| • | Sidesway |
| • | Twist |
A misaligned frame rail may move up or down or to the side of where the rail should be. These possibilities must be checked.
The easiest way to check body alignment is with tramming gages and universal measuring systems made for this purpose. Detailed instructions are normally supplied at the time of purchase. Instructions for equipment usage are not given in this manual.
Whether alignment is checked with or without gauges, the vehicle must be parked on a level section of floor.
Certain conditions call for preliminary inspections before actually inspecting the frame. Suspension or axle problems may make it appear that the vehicle frame is out of alignment. If an axle shifts, a diamond or sidesway may appear to exist when, in fact, they do not. A weak spring may make the vehicle appear to have a twisted frame.
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.
