Cobalt L4-2.2L (2008)
Alignment: Testing and Inspection
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.
*
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.
*
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.
Important: All dimensions are measured vertical to the ground. Trim height should be within ±10 mm (±0.39 in) to be considered correct.
Measuring the J and K Dimension
Use the following procedure to check the J and K dimensions:
1. Measuring the J dimension for the left and right side of the vehicle inboard of the pinch-weld flange at 544 mm (21.4 in) from the centerline of the
front wheel.
2. Compare the measurement to the J specification. Refer to Trim Height Specifications (See: Suspension/Specifications/Trim Height Specifications)
.
3. If the measurement is outside of the specified range, replace the front springs. Refer to Strut, Strut Component, and Spring Replacement (See:
Suspension/Suspension Strut / Shock Absorber/Service and Repair/Front Suspension Strut/Strut, Strut Component, and Spring Replacement) .
4. Using your hands, lift the rear bumper approximately 38 mm (1.59 in).
5. Gently remove your hands and allow the vehicle to lower.
6. Using your hands, jounce the rear of the vehicle downward approximately 38 mm (1.59 in).
7. Gently remove your hands and allow the vehicle to rise.
8. Measuring the K dimension for the left and right side of the vehicle inboard of the pinch-weld flange at 560 mm (22 in) from the centerline of the
rear wheel.
9. Compare the measurement to the K specification. Refer to Trim Height Specifications (See: Suspension/Specifications/Trim Height Specifications
) .
10. If the measurement is outside of the specified range, replace the rear springs. Refer to Coil Spring Replacement (See: Suspension/Suspension
Spring ( Coil / Leaf )/Service and Repair/Rear Suspension Coil Spring/Coil Spring Replacement) .
Measuring the Z Dimension
