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MAINTENANCE
Crusader
MC-8
[ ,.c,_1-_1 _ _ _ DATE~J~ul+-+-y,~19~73~-l
MANUAL
FRONT AXLE
FRONT AXLE
DESCRIPTION
The front axle is of I-beam construction using a
forged center and steering knuckles. Steering knuckle
pins a~e tapered, drawn into the axle center by
tighten mg the nut at the upper end of the pin. The pin
then becomes an integral part of the axle center.
Steering knuckles are bushed in the upper and
!owe~ pin bosses so that they may turn freely about.
the pms. Bronze bushings with grooves on the inside
allow grease to flow uniformly to high-pressure areas.
Grease fittings are installed at both upper and lower
knuckle pin bosses.
The two steering knuckle assemblies are connected
to each other by the tie rod which is threaded at each
end and held securely in position by clamps.
Right-hand and left-hand threads are provided to
simplify toe-in adjustment.
Wheel bearings, air suspension, steering, and brake
parts which are mounted on the front axle are
described in the applicable sections of this manual.
FRONT END ALIGNMENT
Correct front end alignment must be maintained.
for ease of steering and satisfactory tire life. Road
-~hock, vibrations, normal stresses and strains set up
m the front end system under average operation can
result in loss of front end alignment.
If
incorrect front end alignment is suspected, front
wheel balance should first be checked to make sure
that the difficulties are not originating from out-of.
balance front wheels. A check of tire inflation, wheel
installation and run out, wheel bearing adjustment,
tie rod and drag-link end wear should also be made.
_Correct front end alignment can only be main-
tamed when parts in the steering knuckle are in
satisfactory condition.
Factors in front end alignment are as follows:
1.
Front wheel toe-in: The distance the wheels are
closer together at the front than at the rear.
2.
Front wheel camber: The amount the wheel in-
clines from the vertical plane. "Positive" camber
means the wheels lean outward at the top.
"Negative" camber means the wheels lean inward
at the top, and "Zero" camber means that the
wheels are in a vertical plane.
3.
Axle caster: The fore and aft inclination from
vertical of the steering knuckle. "Positive" caster
is inclination of the top of the steering knuckle
towards the rear of the vehicle. "Negative" caster
is the inclination of the top of the steering
knuckle towards the front of the vehicle. "Zero"
caster means no inclination of the steering
knuckle.
4.
King pin inclination: The amount king pins are
inclined inward at the top.
5.
Steering Geometry: The science of keeping the
front wheels in proper alignment during left or
right turns.
CAMBER ADJUSTMENT
Before checking front wheel camber jack up the
front axle of the vehicle and check wheel bearings
and steering knuckle pins. To do this attach a camber
gauge to the wheel collar, pull outward at the bottom
to take up all slack and take the camber reading.
If
the reading differs more than 1 /4 of 1 degree, adjust
the wheel bearings and repeat the check. If - the
second reading is still different in excess of 1/4 of 1
degree, replace the steering knuckle bushings and
pins.
Check wheel run out for excessive wobbling.
Correct any discrepancy either by straightening or
replacing the wheel.
A final camber reading should be made with the
full weight of the coach on a level floor. Camber
readings can be made as illustrated in the alignment
charts if no camber gauge is available. The difference
between the two readings (B minus A) should not
vary more than 3/32" "! 1 /8" from one wheel to the
other.
A larger difference is usually due to a bent axle or
a bent steering knuckle. To determine if the axle is
bent, check the king pin inclination (U minus V on
the chart).
If
the king pin inclination is correct, the
trouble is a bent steering knuckle which should be
replaced.
FRONT WHEEL TOE-IN
Toe-in is utilized to prevent undue tire wear.-To
measure and adjust toe-in, the following procedure is
recommended:
1.
Jack up the front axle.
2.
Using a piece of chalk, whiten the center area of
both front tires around the entire circumference.
3.
Position a scribe or pointed instrument against
the whitened part of each tire and rotate the tires.
The scribe must be held firmly so that a single
straight line is scribed all the way around the tire.
4.
Place a full-floating turning radius gauge plate
under each wheel. Lower the vehicle and remove
the lock pins from the gauge plates.
If
full-
floating turning radius gauge plates are not
available, lower the vehicle and move it back-
ward and then forward approximately six feet.
5.
Set the sliding scale end of a trammel bar on zero
and lock in place. Position the bar at the rear of
the tires and adjust the pointers to line up with
the scribe lines on the tires and lock in place.
(Scale still set at zero.)
6.
Place the trammel bar at the front of the tires.
Adjust the scale end so that the pointers line up
with the scribe marks.
7.
Read toe-in or toe-out from the scale. Scale
should read toe-in 1/16". (Tolerance
t
1/16.)
8.
If
adjustment is necessary, loosen the tie-rod
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