GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Corvette 🢒 Suspension 🢒 Rear Suspension 🢒 Trim Height Adjustment

Tools Required

J 42854 Trim Height Measurement Gauge

Important: When adjusting either the right or left rear trim height the opposite side trim height will be effected.

Trim height should be measured with a full tank of gas and zero passengers or cargo.

An alignment hoist should be checked periodically to assure that both runners are the same height off the ground, side-to-side and front-to-rear.


    Object Number: 296173 Size: SH
  1. Place the vehicle on an alignment rack.
  2. Set the tire air pressure to the proper pressure.
  3. Manually lift the rear of the vehicle up approximately 38 mm (1½ in), gently remove hands and let the vehicle settle.
  4. Repeat the above step two more times for a total of three times.
  5. Use J 42854 to measure the distance between the lowest point of the ball joint (2) and the center of the front side of the lower control arm mounting bolt (1).

    6. Object Number: 200752 Size: SH
  6. Manually push the rear of the vehicle down approximately 38 mm (1½ in), gently remove hands and let the vehicle settle.
  7. Repeat the above step two more times for a total of three times.
    8. • Measure both the right and left sides of the vehicle.
    • The true D trim height is the average of the high and low measurements.
    • Refer to Trim Height Specifications in Suspension General Diagnosis.

    Object Number: 192478 Size: SH

    Important: One complete turn of the adjustment bolt is equal to 2 mm (5/64 in).

  8. Remove the retainers (1) on the top of the spring bolts (2).
  9. Adjust the D trim height by turning the spring bolt.

    10. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  10. Perform the jounce procedures again and measure the D trim height.

    11. Object Number: 200316 Size: SH

    Important: Do not exceed the maximum difference between the right and left rear spring stud heights.

  11. Measure the rear spring stud heights (1). Refer to General Specifications .
  12. Install the retainers to the bolts.
  13. Lower the vehicle.