SMU - Revised Trim Height Inspection

This bulletin is being issued to revise the Trim Height Inspection procedure in the Suspension General Diagnosis sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.

The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.

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:

1. Make sure the vehicle is on a level surface, such as an alignment rack.
2. Remove the alignment rack floating pins.
3. Set the tire pressures to the pressure shown on the certification label. Refer to Label - Vehicle Certification, Tire Place Card, Anti-Theft and Service Parts ID.
4. Check the fuel level. Add additional weight if necessary to simulate a full tank.
5. Make sure the rear compartment is empty except for the spare tire.
6. Close the doors and hood.

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 the 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 the 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.

1. For vehicles equipped with a torsion bar suspension turn the bolt that passes through the torsion bar adjuster clockwise to raise the and counterclockwise to lower the height adjustment.
2. For vehicles without torsion bars, replace damaged or worn components as necessary.

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

Important: All dimensions are measured vertical to the ground. Cross vehicle D heights should be within 10 mm (0.39 in) to be considered correct.

1. Place hand on the rear bumper and jounce the rear of the vehicle. Make sure 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.

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




4. Measure the D height by measuring the distance between the bumper bracket and the top of the jounce bumper pad on the rear axle tube.
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 number is the average of the highest and the lowest measurements. Refer to Trim Height Specifications.
8. If these measurements are out of specifications, inspect for the following conditions:

•	Sagging front suspension--Refer to Torsion Bar Replacement.

•	Sagging rear leaf springs--Refer to Leaf Spring Replacement.

•	Improper tire inflation--Refer to Label - Vehicle Certification, Tire Place Card, Anti-Theft and Service Parts ID.

•	Improper weight distribution

•	Collision damage