add-on axles are installed by others on the truck chassis which allow
operator control for weight transfer from other axles (i.e., air lift axles).
When operating a loaded vehicle, the driver must keep all
adjustable axles on the ground at all times, supporting their
share of the vehicle’s load. Failure to do so can overload other axles,
tires, wheels, springs, steering components, brakes and frames,
resulting in early component failure, loss of vehicle control, possible
property damage and personal injury.
TWO-SPEED REAR AXLE (IF EQUIPPED)
A two-speed rear axle allows the driver to select a LO range for greater
pulling power and a HI range for greater road speed and fuel economy.
These ranges can also be used to provide additional steps between
transmission shifts when driving on steep grades and/or fuel economy
may be factors.
Note: Do not shift between ranges when the speed control is on.
Never shift a two-speed axle when descending a steep grade as
this may cause loss of vehicle control and result in personal injury.
Axle shifting
Manual transmissions:
•To downshift, select the next lower gear, release and depress the
accelerator pedal rapidly, or while holding the accelerator pedal down,
release and engage the clutch rapidly. Note:The clutch method is
recommended when driving at slower speeds.
• To upshift, keep the accelerator pedal down, select the next higher
gear, release the accelerator and pause until the axle upshifts. Note:
De-clutch for smoother axle upshifts when driving at slower speeds.
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Automatic transmissions:
•Use LO range for when you drive
a fully loaded vehicle on a severe
grade or in congested traffic. To
activate LO range, press the
upper portion of the switch.
• Use HI range for all normal
driving conditions with a lightly
loaded or partially loaded vehicle.
To activate HI range, press the
lower portion of the switch.
Note: You cannot split-shift with an automatic transmission. Also,
downshifting above 40 mph (64 km/h) may result in transmission or axle
damage.
Shifting the axle from LO to HI range - vehicle stopped
Place the transmission in N (Neutral), then press the lower part of the switch.
Shifting the axle from LO to HI range - vehicle moving
Accelerate to approximately 35 mph (56 km/h), press the lower part of
the switch while the transmission is in N (Neutral), then release and
apply the accelerator.
Shifting the axle from HI to LO range - vehicle stopped
Place the transmission in N (Neutral), then press the upper part of the switch.
Note: Do not shift the axle to LO range with the vehicle in motion.
Split-shifting (combined axle and transmission shift - manual
transmissions only)
Split-shift sequence
Ratio
combination 1234567891011
Transmission
gear 1st 1st 2nd 2nd 3rd 3rd 4th 4th 5th 6th 6th
Axle range LO HI LO HI LO HI LO HI LO LO HI
To downshift the axle to a slower ratio and shift the transmission, shift
the transmission and move the control switch to the lower ratio before
the clutch is re-engaged.
To upshift the axle and shift the transmission, move the control switch
to a faster ratio and make the transmission shift in the usual manner.
LOW
2SPD
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Installing the axle shafts
1. Remove the covers from the wheel ends
2. Shift the differential lock to the unlocked position (disengaged)
position.
3. Install the axle shafts
•Place the gaskets on the wheel hub studs.
•Push the right-hand axle shaft and gasket into the wheel end and
housing until the shaft stops against the differential shift collar.
•Push down and in on the axle shaft flange and rotate the shaft until
the splines of the shaft and shift collar are engaged.
•Push the axle shaft further into the housing until the shaft stops
against the differential side gear.
•Push down on the axle shaft flange and rotate the shaft until the
splines of the shaft and side gear are engaged.
•Push the axle shaft completely into the housing until the axle shaft
flange and the gasket are flush against the wheel hub.
•Install the left-hand axle shaft and gasket into the wheel end.
4. If tapered dowels are required, install them at each stud and into the
flange of the axle shaft. Use a punch or drift and hammer, if needed.
5. Install the fasteners and tighten to correct torque value. Refer to the
Service Manual.
Towing the vehicle with the rear wheels suspended
Note:To avoid damage to the cab roof or air deflector when towing the
vehicle backward (rear wheels suspended) the air deflector must be
removed.
Whenever possible, it is preferable to tow a disabled vehicle from the
rear by raising the rear of the chassis. When towing a vehicle with the
rear of the chassis suspended the front wheels must be locked in the
straight-ahead position.
Vehicles equipped with a manual-shift transmission must have at least
1.0 pint (0.5L) of transmission fluid drained from the case. This will
prevent the transmission fluid from entering the clutch housing and fluid
saturating the clutch discs. Make sure that the transmission fluid is
replaced before the vehicle is returned to service.
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GENERAL SERVICING GUIDELINES AND PRECAUTIONS
As with any machine, care should be taken to avoid being injured when
performing maintenance, repairs or system checks. Improper or
incomplete service could result in the vehicle not working properly
which, in turn, may result in personal injury or damage to the vehicle or
equipment. It is the operator’s responsibility to see that the vehicle
receives proper care and maintenance. If you have any questions about
performing some service, have the service done by a qualified technician.
Servicing guidelines
When servicing your vehicle, always:
•turn off the ignition unless the particular procedure calls for the
engine to be running.
•set the parking brake or chock the wheels.
•use support stands, not a jack, whenever you must be under a raised
vehicle.
•do not smoke.
•wear safety glasses for eye protection.
•operate the engine in a well-ventilated area
•do not work on the brakes or the clutch unless the proper precautions
are taken to avoid inhaling friction material dust.
•do not wear loose-fitting clothing, hanging jewelry, watches or rings.
•avoid contact with hot metal parts. Allow the hot components to cool
before working with, or around them.
Quality service parts are available through your dealer. If dealer parts are
not used, the owner must make sure that the parts that are being used
are equivalent quality to dealer parts.
The use of inferior parts can adversely affect the quality and
reliability of your vehicle which, in turn, can result in property
damage, personal injury or death.
Note:To avoid damage to the vehicle’s electrical components, disconnect
the positive (+) and negative (-) battery cables prior to electric welding.
Attach the welder ground cable as close as possible to the part being
welded. If it is necessary to weld close to an electrical component, it is
recommended that the electronic component be temporarily removed.
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If you drive in extremely hot climates:
•It is still necessary to maintain the coolant concentration
above 40%.
•NEVER decrease the coolant concentration below 40%.
•Engine coolant concentrations below 40% will decrease the
corrosion protection characteristics of the engine coolant and
may cause engine damage.
•Engine coolant concentrations below 40% will decrease the
freeze protection characteristics of the engine coolant and may
cause engine damage.
•If available, refer to the chart on the coolant container to
ensure the coolant concentration in your vehicle will provide
adequate protection at the temperatures in which you drive.
Vehicles driven year-round in non-extreme climates should use a 50/50
mixture of engine coolant and distilled water for optimum cooling system
and engine protection.
Fan clutches
Your vehicle’s cooling system is equipped with a viscous fan clutch.
•The fan clutch helps control cooling, increase performance, improve
fuel economy and reduce noise.
•The fan clutch is controlled by bimetallic spring sensors. Do not
tamper with these sensors as this may change their calibration or keep
the fan clutch from operating at all.
Stay clear of the fan/fan area while the engine is running or
possible personal injury may occur.
FUEL FILTER/WATER SEPARATOR
Do not drain water separator while engine is running. Fuel may
ignite if separator is drained while engine is running or vehicle is
moving.
The fuel filter/water separator removes any contaminated particles
and/or water from the fuel before the fuel enters the engine.
The fuel filter/water separator should be drained as recommended in the
Scheduled Maintenance Guidechapter.
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•Fuel economy may decrease with lower temperatures during the first
8–10 miles (12–16 km) of driving.
•Flat terrain driving improves fuel economy over hilly roads.
•Transmissions give their best fuel economy when operated in the top
cruise gear and with steady pressure on the accelerator.
•Close windows for highway driving.
NOISE EMISSIONS – EXTERIOR
In order to comply with the federal exterior noise regulations, your
vehicle may be equipped with noise emission items. Depending on the
vehicle configuration, it may have all or some of the following items:
Air Intake System
•Air Cleaner:should be inspected and its location should not be
altered. Do not alter inlet and outlet piping.
Body
•Wheel Well:splash shields, cab shields and under-hood insulation
should be inspected for deterioration, dislocation, and orientation.
Cooling System
•Check the fan for damage to blades; replace, if damaged, with the
recommended parts. Inspect for fan to shroud interference, and any
damage to shroud such as cracks and holes.
•The fan ratio should not be changed and the fan spacer dimensions
and positions should not be altered.
•Inspect the fan clutch for proper operation, make sure that the fan is
disengaged when cooling of the engine is not required.
•Check for proper operation of radiator shutters, if equipped. The
shutters should be open during normal operating temperatures.
Engine and Driveline System
•Transmission Enclosure:inspect for cracks, holes, and tears. Clean
any deposits such as oil, dirt, and stones.
•Engine valve covers and block covers are made to damp out engine
mechanical noise and, if needed, should be replaced with
recommended parts. Check for mechanical isolations.
Exhaust System
•Inspect the exhaust system for leaks at various joint connections and
tighten the clamps.
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Do not let the reservoir for the master cylinder run dry. This
may cause the brakes to fail.
CLUTCH FLUID/LINKAGE ADJUSTMENTS
Clutch fluid (if equipped)
Check the clutch fluid level. Refer to theScheduled Maintenance
Guidechapter for the service interval schedules.
During normal operation, the fluid level in the clutch reservoir should
remain constant. If the fluid level drops, maintain the fluid level at the
step in the reservoir.
Use only a DOT 3 brake fluid designed to meet manufacturer
specifications. Refer toLubricant specificationsin this chapter.
Carefully read cautionary information on product label. For
additional information see product Material Safety Data Sheet
(MSDS). For 24-hour MEDICAL EMERGENCY INFORMATION on
Ford-Motorcraft products call: 1-800-959-3673 (FORD). Failure to
follow these instructions may result in personal injury
1. Set the parking brake, shift into 1
(First) and turn the engine off.
2. Open the hood.
3. Clean the reservoir cap before
removal to prevent dirt and water
from entering the reservoir.
4. Remove cap and rubber
diaphragm from reservoir.
5. Add fluid until the level reaches
the step in the reservoir.
6. Reinstall rubber diaphragm and cap onto reservoir.
Clutch linkage (if equipped)
Lubricate the clutch linkage using the following procedure. Refer to the
Scheduled Maintenance Guidechapter for the service interval
schedules.
Use a grease which meets manufacturer specifications. Refer to
Lubricant specificationsin this chapter.
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1. Set the parking brake, shift into 1 (First) and turn the engine off.
2. Remove the inspection cover from the clutch housing.
•Transmission and clutch
removed for clarity.
3. With a grease gun, lubricate the clutch release bearing (at one
location) and the clutch release shaft (at two locations) using the grease
fittings provided.
4. Lubricate clutch release wear pads at the two locations where they
contact the clutch release bearing using a brush or similar tool.
5. Install the inspection cover onto the clutch housing.
TRANSMISSION FLUID
Always dispose of used automotive fluids in a responsible manner.
Follow your community’s standards for disposing of these types of fluids.
Call your recycling center to find out about recycling automotive fluids.
Automatic transmission fluid
Refer to your Allison Automatic Transmission Operator’s Manual for
scheduled intervals for transmission fluid checks and changes. Your
transmission does not consume fluid. However, the fluid level should be
checked if the transmission is not working properly, i.e., if the
transmission slips or shifts slowly or if you notice some sign of fluid
leakage.
Automatic transmission fluid expands when warmed. To obtain an
accurate fluid check, drive the vehicle until it is warmed up
(approximately 20 miles [30 km]). If your vehicle has been operated for
an extended period at high speeds, in city traffic or during hot weather,
the vehicle should be turned off for about 30 minutes to allow fluid to
cool before checking.
1. Drive the vehicle 20 miles (30 km) or until it reaches normal operating
temperature.
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