Alignment: Testing and Inspection
Trim Height Inspection
Trim Height Measurements
Trim height is a predetermined measurement relating to vehicle ride height. Incorrect trim heights can cause bottoming out over bumps, damage to the suspension components, and symptoms similar to wheel alignment problems. Check the trim heights when diagnosing suspension concerns and before checking the wheel alignment.
Perform the following before measuring the trim heights:
* Ensure the vehicle is on a level surface, such as an alignment rack.
* Ensure that the suspension is fully supporting the vehicle.
* Remove the alignment rack floating pins.
* Set the tire pressures to the pressure shown on the certification label. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label .
* Inspect the fuel level. Add additional weight if necessary to simulate a full tank.
* To ensure proper weight distribution make sure the rear storage compartment is empty.
* Close all doors, lift gate/trunk and the hood.
Z Height Measurement
Important: K models only-The Z height must be adjusted before the alignment.
The Z height dimension measurement determines the proper ride height for the front end of the vehicle. Vehicles equipped with torsion bars use a adjusting arm in order to adjust the Z height dimension. Vehicles without torsion bars have no adjustment and could require replacement of suspension components.
Important: All dimensions are measured vertical to ground. Cross vehicle Z heights should be within 12 mm (0.47 in) to be considered correct.
1. Jounce the front and rear suspension to obtain at least 38 mm (1.5 in) deflection, then allow the vehicle to settle.
2. Set the top edge of the level on the reference surface of the steering knuckle (C) and extend the level directly under the rear end of the front attachment bolt of the lower control arm (A).
3. While keeping the level in contact with the knuckle reference surface, adjust the level up/down until the bubble indicates it is horizontally level.
4. Extend a tape measure straight down from the center of the attachment bolt. The point where the tape measure and the level intersect is your first measurement.
5. Keep the top edge of the level on the reference surface of the steering knuckle (C) and move the level directly under the front end of the rear attachment bolt of the lower control arm (B).
6. Extend a tape measure straight down from the center of he attachment bolt. The point where the tape measure and the level intersect is your second measurement.
7. Average the 2 readings (add them together, then divide by 2) and write down the result.
8. Repeat steps 1 through 7 a total of 3 times, writing down the results.
9. Average the results (add them together, then divide by 3) and this result is your final Z height number.
10. Compare your Z height number with the Service Information Z height specification. Refer to Trim Height Specifications (Trim Height Specifications) .
Z Height Adjustment
1. For vehicles equipped with a torsion bar suspension, turn the bolt (1) that contacts the torsion arm as needed. One revolution of the bolt (1) into the nut increases the Z height by approximately 6 mm (0.2 in).
2. For vehicles without torsion bars, replace damaged or worn components as necessary.
3. If these measurements are still out of specifications after adjustment or are not equipped with torsion bars, inspect for the following:
* Sagging front suspension-Refer to Torsion Bar and Support Assembly Replacement (Bushing Style) (Torsion Bar and Support Assembly Replacement (Bushing Style))Torsion Bar and Support Assembly Replacement (Link Style) (Torsion Bar and Support Assembly Replacement (Link Style)) .
* Collision damage
D Height Measurement
Important: The left and right D height difference should be no more than 14 mm (0.55 in). Use the following procedure to measure the D height.
1. Lift the rear bumper of the vehicle up about 38 mm (1.5 in).
2. Gently remove your hands and let the vehicle settle.
3. Repeat this operation 2 more times for a total of 3 times.
4. Measure between the axle bracket and jounce bumper mount bracket as shown in graphic.
5. Lift the rear bumper of the vehicle up about 38 mm (1.5 in),
6. Gently remove your hands and let the vehicle settle.
7. Repeat this operation 2 more times for a total of 3 times.
8. The true D height is the average of the measurement from step 4 and step 8. The side to side difference in D height must not exceed 14 mm (0.55 in).
9. If any of these measurements are out of specifications, inspect for the following conditions:
* Worn or damaged suspension components
* Collision damage