Figure 12-21.Checking the turning radius.
point. This will cause less wear on the steering gears. A
suggested procedure is as follows:
1. Position the wheels straight ahead; check the
position of the steering wheel. It should be centered; if
it is not, center it now. To find center, turn the steering
wheel all the way to the left and count the number of
turns while turning it all the way to the right. Now, turn
the steering wheel back half the number of turns. Now
check the front wheels; one may be turned in more or
less than the other; adjust them so that they are parallel
with the frame of the vehicle.
2. At this point, your toe reading should be zero (0).
Now, adjust the toe by turning the tie rod end sleeves.
They should be adjusted in equal amounts. If the setting
is 1/4-inch toe-in, you take 1/8th off the right and 1/8th
off the left wheel.
Now that we have covered the angles you can adjust,
it is equally important that you understand the
nonadjustable angles and how they can be checked as
presented in the following section.
Turning radius is nonadjustable, but it can be
checked (fig 12-21). Using turntable pads calibrated in
degrees, turn the right wheel 20 degrees and read the
setting on the left wheel. Then turn the left wheel 20
degrees and read the setting on the right wheel. Check
your readings against the manufacturers specifications.
If all other adjustments are correct (caster, camber,
toe-in), and the turning is incorrect, replacement of the
steering arm is the only method of correction.
Figure 12-22.Steering axis inclination.
STEERING AXIS INCLINATION (SAI)
Steering axis inclination is nonadjustable; it is the
angle formed by the true vertical centerline of the ball
joints or kingpin (fig. 12-22). SAI and camber are
closely related. If you change the camber by tilting the
top of the wheel in or out, you change SAI an equal
amount. As previously stated, SAI is nonadjustable;
therefore, the angle built into the steering knuckle
does not change unless it is bent.
To check the spindle or spindle support, measure
both camber and SAI. If camber is positive, add the
two measurements. If camber is negative, subtract the
camber measurement from the SAI measurement. The
resulting figure is the angle built into the spindle
support. Check the manufacturers specifications. If
your readings differ from the manufacturers, then the
only corrective action is to replace the bent spindle.
STEERING AND ALIGNMENT
The driver can sense steering and alignment trouble.
He or she can detect hard steering or play in the steering
system and will call you to find the trouble and remedy
it. The following are some complaints and their possible
1. When breaking, vehicle pulls to one side:
Uneven tire pressure
Caster incorrect or uneven
Wheel bearing too tight