D Height Measurement

The D height measurement determines the proper ride height for the rear end of the vehicle. There is no adjustment procedure. Repair may require replacement of suspension components.

1. Place hand on the rear bumper and jounce the rear of the vehicle. Ensure that there is at least 38 mm (1.5 in) of movement while jouncing.
2. With the vehicle on a flat surface, lift upward on the rear bumper 38 mm (1.5 in).
3. Allow the vehicle to settle into position.

4. Courtesy of GENERAL MOTORS COMPANY

   IMPORTANT:

   Measure the metal to metal contact points of the rear axle to the frame on the inboard side of the leaf springs.

   Measure the D height by measuring the distance between the rear axle tube and the frame (1).

5. Repeat the jouncing operation 2 more times for a total of 3 times.
6. Use the highest and lowest measurements to calculate the average height.
7. The true D height dimension is the average of the highest and the lowest measurements. Trim Height Specifications 
8. If these measurements are out of specifications, inspect for the following conditions:
   • Sagging rear leaf springs - Rear Leaf Spring Replacement (Chassis Cab)Rear Leaf Spring Replacement (Except Chassis Cab)
   • Collision damage