Steering and vibration complaints are not always the result
of improper alignment. Another possibility is tire lead due to worn or improperly
manufactured tires. Lead is the vehicle deviation from a straight path on
a level road without pressure on the steering wheel. Refer to
Radial Tire Lead/Pull Correction
in Tires and Wheels
to determine if the vehicle has a tire lead problem. Before making any adjustment
affecting wheel alignment, make the following inspections to ensure correct
alignment readings and adjustments.
| • | Inspect all the tires for proper inflation pressures. |
| • | Inspect that all tires are of the recommended size. |
| • | Inspect that all tires have about the same tread wear. |
| • | Inspect the wheel bearings for proper adjustment. Correct if necessary. |
| • | Inspect the control arm ball joints, the relay rod, and the tie
rod ends. If they are loose, correct them before adjusting the wheel alignment. |
| • | Inspect the vehicle trim height. If the vehicle trim height is
out of limits, make the necessary corrections before adjusting the wheel alignment.
Refer to
Trim Height Inspection
in Suspension General
Diagnosis. |
| • | Inspect that the steering gear is not loose at the frame. |
| • | Inspect the lower control arms for loose bushings. |
| • | Inspect the stabilizer shafts for loose or missing parts. |
| • | Inspect for leaking or worn out shock absorbers. |
| • | Inspect the remaining suspension and steering components for damage.
All worn parts must be replaced prior to adjusting the wheel alignment. |
| • | Inspect the vehicle for stability. The fuel tank should be full
or the vehicle should have compensating ballast. |
Consideration must be given to excess loads, such as tool boxes, sample
cases, etc. If these items are normally carried in the vehicle, they should
remain in the vehicle during alignment adjustments. Consideration should also
be given to the condition of the equipment being used to adjust alignment.
Be sure to follow the equipment manufacturer's instructions. Regardless of
the equipment used to adjust alignment, the vehicle must be on a level surface,
both front-to-rear and side-to-side.
Satisfactory vehicle operation may occur over a wide range
of alignment settings. However, should the settings vary beyond the specifications,
the alignment angles should be corrected.
Perform the following steps to measure the wheel alignment angles:
- Install the alignment equipment according to the manufacturer's
instructions.
- Jounce the front bumpers lightly three times and jounce the rear
bumpers lightly three times to normalize the suspension prior to measuring
the angles.
- Measure the alignment angles.
- Record the readings. If adjustments are required, make them in
the following order:
