vibration complaints. For future reference, explain to the operator that misalignment
rarely causes vibration.
Road Test.
If possible, road test the vehicle before beginning the alignment. Pick a
quiet, level street for the road test. The road test can be brief, but it should be complete.
Make a series of stops and turns. Drive several blocks in a straight line. Listen, look,
and feel for road wander, unusual noises, pulling, hard steering effort, excessive road
shocks, and other handling problems. The results of the road test will give you a basis
for making other pre-alignment checks and for determining what alignment adjustments
will be necessary.
To the shop.
After the road test is complete and you have determined it is an alignment
problem, drive the vehicle onto the alignment rack. Make sure that the front tires are
centered on the turning plates.
Before beginning the alignment procedures, always check ride height, the tire and rims,
and the vehicle's underbody.
Height.
Check the riding height. If incorrect, adjust the height if the suspension uses
torsion bars, or replace parts, as needed.
Before deciding that ride height is incorrect, check the backseat, trunk, or bed for
excess weight. Remove excess weight before proceeding with the height check.
Worn parts.
Once the vehicle is properly positioned on the rack, raise the front and rear
wheels to check for worn parts. Do not skip this step. It is impossible to align a vehicle
with worn or damaged parts.
CAUTION
If the vehicle is equipped with an electronic suspension system, open the trunk and turn
the suspension switch off before raising the vehicle.
Raise the suspension so the ball joints are unloaded. On a suspension with the spring
on the lower control arm, place the jack under the control arm. On suspensions with the
spring on the upper control arm or around the MacPherson strut, place the jack on the
frame. On solid axles, place the jack under the axle.
With the vehicle properly raised, perform a shake test. Grasp the wheel at the front and
back and shake it. If the vehicle has an offset strut assembly, it may be necessary to
grasp the wheel at about 45° counterclockwise from the top and bottom and then shake
it. If the wheel moves excessively in any direction or makes knocking or clunking noises,
look for worn or loose parts.
As a general rule, looseness when the wheel is shaken from the top and bottom
indicates worn ball joints or very worn control arm or strut rod bushings. Worn tie rods or
other steering system parts will cause looseness when the wheel is shaken from front
and back. Loose or worn out wheel bearings usually cause looseness in all directions. If
looseness is detected, have an assistant shake the wheel while you look for worn parts.
Sometimes it is necessary to pry on parts using a pry bar. On some vehicles, the tie
rods will be looser when the wheels are on the ground. Check your service manual for
recommendations.
NAVEDTRA 14050A
9-20