Follow the tire manufacturer's
recommended cold inflation pressure for
the tire size, load range (ply rating) and
steer axle loading typical for their operation
(each steer axle tire equals ½ steer axle
loading).
Special applications may warrant a setting
based on experience with the type of tire
operating loads and conditions. Radial tires
are more sensitive to toe-in setting than
bias ply tires. Fine tuning school bus
alignment to line-haul truck standards
does not drastically improve tire tread life.
STEERING SYSTEM
INSPECTION
WARNING
Failure to maintain the steering
system in proper condition can cause
reduced steering ability resulting in
property damage, personal injury or death. Note:
Have any steering problems
immediately corrected by a qualified service
technician.
Ask your service technician to examine the
steering mechanism. Only minor
adjustments may be necessary.
Regular inspections should include:
• Checking the tie rod, drag link end
clamp bolts and ball joints for proper
tightness.
• Checking for installation and spread of
cotter pins and tightness of nuts at
both ends of the tie rod and drag link.
• Checking that the pitman arm (steering
arm at steering gear) mounting is tight
and locked. Check system for leaks or
hose chafing. Repair immediately, if
necessary. •
Maintaining proper steering gear and
power steering pump lubricant levels.
• Checking steering column joint bolts
and steering linkage, particularly for
body-to-chassis clearance.
Steering Column Joint Bolts
As a good maintenance practice, check
steering column joint bolt tightness every
60,000 mi (96,000 km) or annually,
whichever occurs first. Do not overtighten
the bolts.
Hydraulic System
Whenever draining and refilling the power
steering's hydraulic system for any reason,
bleed air from the system before returning
the vehicle to service. Failure to bleed the
hydraulic system properly can result in
degradation of power system performance.
Consult an authorized dealer who is aware
of the proper procedures for filling and
bleeding the system.
SUSPENSION SYSTEM
INSPECTION
Note: Do not adjust air suspension height
to any setting other than the specified
setting. Altering the height setting changes
the driveline angle and may result in
unwarrantable component damage, such
as transmission component damage.
Verify drive axle air suspension height and
height control valve performance at engine
oil change intervals.
Periodically check:
• Condition of spring leaves for evidence
of fatigue, bending or breakage.
• Condition of suspension mounting
brackets and bushings.
• Torque rod mounting fasteners for
tightness.
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F650750 (TBC), enUSA, First Printing Maintenance
•
For proper suspension alignment.
Maintain proper alignment at all times.
• U-bolts. After the chassis has been
operating under load for 1,000 mi
(1,600 km) or six months (whichever
comes first), the U-bolt nuts must be
re-torqued. Re-torque the U-bolt nuts
every
37,000 mi (60,000 km)
thereafter. Clean and lubricate the
U-bolt and nut threads and seats to
make sure a like new condition when
re-torqueing. See
Spring U-Bolt
Check (page 223).
FRAME AND TOW HOOK
INSPECTION
Your vehicle's chassis is manufactured
with frame rails of either HSLA steel or
heat-treated steel. Handle each in a
specific manner to make sure maximum
service life. Consult the service manual or
an authorized dealer before attempting
frame repair or modification.
It is important, particularly on vehicles that
use tow hooks frequently, to inspect the
front and rear tow hooks for damage or a
loose mounting.
REAR AXLE FLUID CHECK
Your rear axle may have an optional
synthetic lubricant that allows the use of
extended service intervals. A tag on the
filler plug identifies the use of the synthetic
lubricant.
Only use a lubricant that meets
manufacturer specifications. Only use a
lubricant that meets manufacturer
specifications. Use of a non-approved rear
axle lubricant may cause internal axle
component damage. See Capacities and
Specifications
(page 256). Checking the Fluid Level
1. Park your vehicle on level ground.
2. Set the parking brake and shift into
position neutral (N) or park (P). Turn
the engine off.
3. Clean any dirt from around the axle filler plug.
4. Remove the filler plug and inspect the lubricant level. It should be at the
bottom of the filler plug opening.
5. Add lubricant, if necessary, through the
filler plug opening.
6. Clean and install the filler plug securely.
Changing the Fluid
Note: Drain the rear axle while the lubricant
is warm.
1. Park your vehicle on level ground.
2. Set the parking brake and shift into position neutral (N) or park (P). Turn
the engine off.
3. Clean any dirt from around the axle filler and drain plugs.
4. Remove the filler and drain plugs. Drain
the lubricant into a suitable container.
Dispose of all used automotive fluids
in a responsible manner following your
local authorized standards.
5. Clean and install the drain plug securely.
6. Add lubricant through the filler plug opening.
7. Clean and install the filler plug securely.
SPRING U-BOLT CHECK
Check U-bolt nuts and re-torque every
37,000 mi (60,000 km)
after initial
1,000 mi (1,600 km) re-torque. Clean and
lubricate the U-bolt and nut threads and
seats to make sure they are in peak
condition when re-torqued.
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F650750 (TBC), enUSA, First Printing Maintenance
