GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 Torrent 🢒 Suspension 🢒 Suspension General Diagnosis 🢒 Trim Height Inspection

Trim Height Measurement

Trim height is a predetermined measurement relating to vehicle ride height. Incorrect trim heights can cause the vehicle to bottom 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:

    • Set the tire pressure to the specifications shown on the certification label. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label .
    • Check the fuel level. Add additional weight if necessary to simulate a full tank.
        One U.S. gallon of gasoline weighs approximately 6.5 lbs. One liter of gasoline weights approximately 0.70 kg.
    • Make sure the passenger and rear compartments are empty, except tor the spare tire.
    • Make sure the vehicle is on a flat and level surface, such as an alignment rack.
    • For vehicles equipped with automatic level control, ensure the system is functioning properly.
    • Check that all the vehicle doors are securely closed.
    • Check that the vehicle hood and rear deck lids are securely closed.
    • Check for installed after market accessories or modifications that could affect trim height measurement:
       - Larger of smaller than production wheels and tires
       - Lifting or lowering kits
       - Wheel opening flares or ground affects

Measuring the P and R Heights
Object Number: 1858097 Size: SH

Important: The left and right P and R height difference should be no more than 12 mm (0.47 in).

Use the following procedure to measure the P and R dimensions:

  1. Lift the front 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 vertically from the ground to the bottom lip of the wheel opening through the centerline of the front wheel, P height.
  5. Push the front bumper of the vehicle down 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. Re-measure the P height as in step 4.
  9. The true P height is the average of the measurements taken in steps 4 and 8. Refer to Trim Height Specifications .
  10. Repeat the above steps at the rear of the vehicle for the R heights.
  11. If the P and R heights are outside of specifications, measure the Z and D heights.

Measuring the Z Height
Object Number: 1616905 Size: SH

Important: 

   • In order to obtain the proper measurement, Z will equal inner minus the outer.
   • The left and right Z height difference should be no more than 12 mm (0.47 in).

Use the following procedure to measure the Z height:

  1. Lift the front 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. Repeat this jouncing operation 2 more times for a total of 3 times.
  5. Measure from the center of the lower ball joint (A) to the alignment rack.
  6. Measure from the center of the cradle (B) to the alignment rack.
  7. The difference between these 2 measurements is the Z height.
  8. Push the front bumper of the vehicle down about 38 mm (1.5 in).
  9. Gently remove your hands and let the vehicle settle.
  10. Repeat this operation 2 more times for a total of 3 times.
  11. Re-measure the Z height as in step 4.
  12. The true Z height is the average of the measurements taken in steps 4 and 8. Refer to Trim Height Specifications .

If any of these measurements are out of specifications, inspect for the following conditions:

    • Worn or damage suspension components
    • Collision damage

Measuring the D Height
Object Number: 1616908 Size: SH

Important: 

   • In order to obtain the proper measurement, D will equal inner minus the outer.
   • The left and right D height difference should be no more than 12 mm (0.47 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 from the center of the inner pivot bolt (A) to the alignment rack.
  5. Measure from the center of the outer pivot bolt (B) to the alignment rack.
  6. The difference between these 2 measurements is the D height.
  7. Lift the rear bumper of the vehicle up about 38 mm (1.5 in).
  8. Gently remove your hands and let the vehicle settle.
  9. Repeat this operation 2 more times for a total of 3 times.
  10. Re-measure the D height as in step 4.
  11. The true D height is the average of the measurements taken in steps 4 and 8. Refer to Trim Height Specifications .

If any of these measurements are out of specifications, inspect for the following conditions:

    • Worn or damage suspension components
    • Collision damage