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:
- Set the tire pressures to the pressure shown on the certification
label. Refer to
Vehicle Certification Label
in General Information.
- Check the fuel level. Add additional weight if necessary to simulate
a full tank.
- Make sure the rear compartment is empty except for the spare tire.
- Make sure the vehicle is on a level surface, such as an alignment
rack.
- Close the doors.
- Close the hood.
- All dimensions are measured vertical to the ground. Trim heights
should be within 13 mm (0.5 in) to be considered correct.
The measurements are to be used for comparison only.
Front Axle Height Measurement
The C height dimension measurement determines the proper ride height
for the front end of the vehicle. Vehicles without torsion bars have no adjustment
and could require replacement of suspension components. The B height dimension
measurement determines if the front axle is bent. Check the suspension
and steering components for any binding conditions.
- Lift the front bumper
of the vehicle up about 38 mm (1.5 in).
- Gently remove your hands.
- Allow the vehicle to settle into position.
- Repeat this jouncing operation 2 more times for a total of 3 times.
- Measure from the center line to the bottom inside frame rail in
order to obtain the C height measurement for the axle.
- Measure from the axle center line of each front wheel to the bottom
of the axle beam to obtain the B height measurement for the front axle.
- The true C and B height dimension is the average of the high and
low measurements. Refer to
Trim Height Specifications
.
Rear Single Axle Height Measurement
The C height dimension measurement determines the proper rear end ride
height. There is no adjustment procedure. Repair may require replacement of
suspension components.
- Make sure the vehicle
is on a flat level surface.
- Measure the C height by measuring the distance between the rear
axle center line to bottom inside of frame rail.
- Check the suspension components for any binding conditions. Allow
the vehicle to settle into position.
- Measure the C height dimension.
- The true C height dimension number is the average of the high
and the low measurements.
- If these measurements are out of specifications, inspect for the
following conditions:
• | Improper weight distribution |