Z Height Measurement

WARNING: This page is about a different car, the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The Z height measurement determines the proper ride height for the front end of the vehicle. Vehicles equipped with torsion bars use an adjusting arm to adjust the Z height. Vehicles without torsion bars have no adjustment and may require replacement of suspension components.

IMPORTANT: All dimensions are measured vertical to the ground. Cross vehicle Z heights should be within 24 mm (0.9 in).

Place hands on the front bumper and jounce the front of the vehicle. Make sure that there is at least 38 mm (1.5 in) of movement while jouncing.
Allow the vehicle to settle into position.

Fig 1: Measuring Front Ride Height (Z Height)

Courtesy of GENERAL MOTORS CORP.

Measure from the centerline (1) of the lower control arm bushing bolt (4) down to the machined edge of the steering knuckle (2) in order to obtain Z height measurement (3).
Repeat the jouncing operation and measurement 2 more times for a total of 3 times.
Use the highest and lowest measurements to calculate the average height.
The true Z height dimension number is the average of the high and the low measurements. Refer to Trim Height Specifications .
If these measurements are out of specifications, inspect for the following conditions:
- Sagging front suspension. Refer to Shock Module Replacement in Front Suspension.
- Collision damage.