Measuring the Z Dimension

Fig 1: Z Dimension

Courtesy of GENERAL MOTORS COMPANY

Measurement Definitions 

Z Height: The vertical distance (a) between the lowest point of the bushing hoop (2) on the front suspension to the center of the ball joint (1).

Use the following procedures to measure the Z dimensions:

NOTE:

The left and right Z height differences should be no more than 10 mm (.39 in).

1. Push the front bumper down a minimum of 25 mm (1 in). Perform this step three times.
2. Measure and record the trim height per the "Measurement Definitions" above.
3. Lift the front bumper a minimum of 25 mm (1 in). Perform this step three times.
4. Measure and record the trim height per the "Measurement Definitions" above.
5. The true Z height dimension is the average of the measurements taken in steps 2 & 4. Refer to Trim Height Specifications .
6. If these measurements are out of specifications, inspect for the following conditions:
   • Worn or damaged suspension components
   • Collision damage