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2H-8
WHEELS AND TIRES
(2) Remove axle shaft and shaft gasket. Discard
gasket.
(3) Straighten lip of lockwasher and remove locknut
and lockwasher.
(4) Raise vehicle.
(5) Rotate wheel and tighten adjusting nut to 50
foot-pounds (68 N*m) torque using tool J-25106.
(6) Back off adjusting nut about 1/6-turn or until
wheel rotates freely without lateral movement.
(7) Install and tighten locknut to 50 foot-pounds (68
N*m) torque and bend lockwasher lip over locknut.
(8) Check adjustment and correct if necessary.
(9) Install replacement axle shaft gasket and axle
shaft. Install cone washers, lockwashers, and bolts.
(10) Lower vehicle.
T I R E
R0JJ1HIESS
Roughness, vibration, tramp, shimmy, and thump are
usually caused by excessive wheel or tire runout, cupped
tires, or wheel/tire unbalance. These problem conditions
may also be caused by operation over rough or undulat-
ing road surfaces. Driving the vehicle on different road
surfaces will usually help determine if the road surfaces
or tires are causing the problem.
Always road test the vehicle to determine the exact
nature of the problem. Drive the vehicle for at least
seven miles (11 km) to warm the tires and remove tem-
porary flat spots that may have formed while the vehicle
was parked. Note tire condition and wear and check and
adjust inflation pressures to recommended levels before
road testing.
Radial Tire Performance Characteristics
As a result of their unique construction, radial tires
produce ride, handling, and appearance characteristics
that are noticeably different from conventional tires.
The low speed ride quality or feel of radial tires may
seem harsh when compared to conventional tires. This is
a normal characteristic and is due to the stiff belts used
in radial tire construction. Harshness often leads to the
assumption that the tires are overinflated. Do not un-
derinflate radial tires in an attempt to correct this con-
dition. Inflate radial tires to recommended levels only.
Because radial tire body plies are positioned at a 90
degree angle to the tread centerline, they have highly
flexible sidewalls. It is this flexibility which produces a
characteristic sidewall bulge making the tire appear un-
derinflated. This is a normal condition. Do not attempt
to reduce this bulge by overinflating the tire. Check
inflation pressure using an accurate gauge and inflate
radial tires to recommended levels only.
At speeds of 15 mph (24 km/h) or less, radial tires
may generate a side-to-side or waddle motion. This mo-
tion is a normal radial tire characteristic and is due to
the highly flexible sidewall. An objectionable waddle
condition can be reduced only by rotating the tires.
Wheel balancing will not alleviate this condition.
Proper mounting of radial tires is very important.
Incomplete seating of the tire bead can produce a high
frequency vibration at speeds above 45 mph (72 km/h).
Improper bead seating can be checked by visually in-
specting the tire. Correction involves removing and re-
seating the tire on the wheel.
Because of their construction, radial tires are some-
times less responsive to certain methods of wheel bal-
ancing. Radial tire balancing is best accomplished using
dynamic, two-plane, off-vehicle balance equipment.
Tire Thump
Thump noise is caused by the tire moving over irre-
gularities in the road or by irregularities in the tire
itself. The sound coincides with each wheel revolution.
To determine which tire is causing thump, inflate all
tires to 45 psi (310 kPa) temporarily and drive over the
same roads. If thump stops, reduce the pressure in one
tire at a time and repeat the road test. Perform this
procedure until all tires have been tested and each test is
made with three tires at high pressure and one tire at
recommended pressure. When thump develops again,
the tire just reduced to normal inflation pressure is the
problem tire.
N O T E : Although the procedure for diagnosing
thump
is quite effective with conventional tires, it is consid-
erably less effective with radial tires.
Tire Tramp
Tramp is caused by wheel/tire static unbalance or by
excessive lateral runout of the tire or wheel.
The most effective method for checking static balance
is by using off-vehicle balancing equipment.
Static balance is the result of an equal distribution of
wheel and tire weight about the circumference of the
tire. In this case, weight is distributed about the spindle
in such a manner that the assembly lacks the tendency
to rotate by itself when mounted on the arbor of a
balancing machine.
Static unbalance occurs when an unequal portion of
weight is concentrated at one point on the tire and wheel
(fig. 2H-11). It causes a vibratory-type pounding action
which is referred to as tramp or hop.
Dynamic balance is the result of an equal distribution
of wheel/tire weight around the plane of rotation (fig.
2H-12). This causes the wheel to rotate smoothly about
the axis that bisects the wheel and tire centerline.
Dynamic unbalance occurs when unequal forces are
concentrated at opposing points on the tire circum-
ference. It will cause shimmy and vibration at medium
and high speeds (fig. 2H-12).
The most effective method for balancing wheels and
tires is by using equipment that will correct both static
and dynamic balance. Dynamic, two-plane balancing
equipment is preferable.
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