Section 02-01: Frame | 1996 F-150, F-250, F-350, F-Super Duty Chassis Cab and Bronco Workshop Manual |
NOTE: An alternate method of checking frame alignment is to use a frame gauge.
Frame alignment can be checked without removing the body from the frame (5005) by using the diagonal or X-frame checking method.
This method should be used to identify misalignment prior to any attempt to straighten a frame.
Place the vehicle on a clean, level floor and set the parking brake.
Select at least four points along the left frame side rail (5015) and transfer these points to the floor with a plumb bob. If desired, paper can be taped on the floor along both sides of the vehicle below the frame. Mark the points on the floor as accurately as possible.
Locate the corresponding points along the right frame side rail (5016) and transfer these points to the floor in the same manner.
Move the vehicle away from the marks on the floor, and measure diagonally between all points on the floor. Both measurements should be equal within 6.35mm (1/4 inch).
Measure between corresponding points parallel to the frame side rails. These measurements should be within 3.18mm (1/8 inch) of each other.
The squareness of the frame side rail web to the floor at the spring hangers and at the steering gear mounting location should be within 1.59mm (1/16 inch). The squareness of the frame side rail web to the floor at all other points should be within 3.18mm (1/8 inch). The web and flange should be square at all other points within 3.18mm (1/8 inch).
Any point on one side rail should be within 3.18mm (1/8 inch) ahead, behind, above, or below the corresponding point on the opposite side rail. The frame side rail should not be bowed more than 3.18mm (1/8 inch) for each 2540mm (100 inches) of frame length. The overall width of the frame should not vary more than 3.18mm (1/8 inch).
An alternate method of checking frame alignment is to use Rotunda Laser Measuring System 073-00451 or equivalent.