Rear axles with locking or limited-slip differentials
If your vehicle is equipped with a locking or limited-slip differential, note
the following:
•Power will be transmitted to the opposite wheel should one of the
wheels begin to slip.
•Both wheels must be raised off the ground should it be necessary to
operate one wheel with the vehicle stationary.
If both wheels are not raised off the ground, the one wheel that
is not raised may pull the vehicle off its support, possibly
resulting in personal injury
Driver-controlled differential lock
To prevent the vehicle from moving when servicing the wheels, tires or
brakes, turn the engine off and raise all drive wheels of the locker
differential axle. Axles equipped with NoSPIN Detroit Locker differentials
deliver power to both wheels even when only one wheel is on the
ground.
Failure to raise all drive wheels with this type of differential
could cause the vehicle to move unexpectedly, resulting in
property damage, personal injury or death.
Care should be taken to avoid sudden accelerations when both drive
wheels are on a slippery surface.
Sudden accelerations on slippery surfaces could cause the
wheels to spin, the vehicle to turn sideways on a crowned road
surface or in a turn, possibly resulting in loss of vehicle control and
personal injury.
Some Dana/Spicer drive axles have a driver-controlled differential lock.
The differential lock can lock or unlock the differential when the vehicle
is moving or stopped. When extra traction is required, the differential
lock will provide full power to both axles.
When the differential is locked, the vehicle’s turning radius will increase
(vehicle will “under-steer”)
The differential can be locked or unlocked when the vehicle is moving at
a constant speed of less than 25 mph (40 km/h) and while the wheels
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Check to make sure that the axle mounting U-bolt nuts, attaching or
mounting bolts and nuts are securely tightened. Regularly check front
axle for damage, binding, worn parts and adequate lubrication.
At regular intervals, or during other scheduled maintenance, (tire
rotation/service, wheel bearing service, alignment, etc.) the kingpins
should be checked for excessive wear. Refer to the service manual for
proper procedures.
Toe-in setting - general inspection
Inspecting steer axle tires in the first 3,000–10,000 service miles
(4,800–16,000 service km) will generally show if tires are wearing
normally.
Rapid outside shoulder wear on both tires indicates too much toe-in.
Rapid inside shoulder wear on both tires indicates too much toe-out. In
P&D-type service, left-to-right steer tire tread life differentials up to 40%
can be observed depending on routes and other variables.
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 will equal
1 2steer axle loading).
Special applications may warrant a setting based on past experience with
the type of tire operating loads and conditions. Radial tires are more
sensitive to toe-in setting than bias ply tires. While not insensitive to
vehicle alignment, fine tuning school bus alignment to line-haul truck
standards will not drastically improve tire tread life.
It is essential that correct toe-in and tire pressure be maintained for
optimum tire wear.
Rear axle - general inspection
Check to make sure that the axle mounting U-bolts, attaching or
mounting bolts and nuts are securely tightened. Refer toU-bolt nut
torquein this chapter. Regularly check the rear axle for damaged,
binding or worn parts.
NoSpin Detroit Locker positive locking differential
Vehicles equipped with this type differential have the operator’s manual
supplied with the vehicle. Refer to this manual for maintenance checks.
Brake system - general inspection
Your vehicle is equipped with non-asbestos brake linings. However,
exposure to excessive amounts of brake material (whether asbestos or
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interval to determine if adjustment is necessary. Brake chamber push
rods on original equipment chambers now incorporate a stroke indicator
to aid in adjustment checks; an orange paint marker near the base of the
push rod. If the push rod is clean and the brakes require adjustment, the
orange marker can be seen protruding from the chamber when the
brakes are applied.
Slack adjusters should also be checked to ensure proper operation of the
adjuster mechanism at the six-month interval. Push rod travel should be
kept at a minimum without the brakes dragging.
Inspect the brake lining every maintenance interval. When brake lining or
blocks are worn to within 1/16 inch (1.6 mm) of rivets, brake lining must
be replaced. This inspection or adjustment should only be performed by
a qualified technician and must be in accordance with instructions
provided by the service manual.
Do not back off or disconnect the front brakes so that they are less
effective, letting the rear brakes do all the stopping of the vehicle. Do
not overlook the brakes on the trailer, either. Brake condition on the
trailer is just as important as the tractor. Proper brake balance on trucks
and tractor-trailers is essential for effective braking.
Once a year, the entire brake system must be inspected. Check the
following:
•Any rubber as it may deteriorate whenever used. Rubber brake
components should be inspected by a qualified technician and
replaced as necessary. Replacement intervals vary according to the
severity and length of vehicle service.
•Condition of brake drums, brake chambers and slack adjusters.
•System for air leaks.
•Hose or pipes for rust, damage and deterioration.
•Operation of service and parking brakes.
Some parts such as air brake chamber diaphragm, air compressor and air
cleaner should be inspected periodically and replaced if considered
unserviceable.
Air brakes - air dryer
Performance of desiccant or after-cooler type air dryers is dependent on
climatic conditions in which your vehicle is operating. Maintenance
schedules must be established for each specific operation.
The use of an air dryer on a vehicle does not eliminate the need to
periodically drain the air reservoirs.
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•Always loosen rim clamps before complete removal of nut from stud
(cast spoke wheels). With loosened nuts on stud, strike clamps with a
heavy hammer and be sure each clamp is loose.
•Always deflate tires completely before removing locks or side rings.
•Always inflate tires in a safety cage.
•Never mix rim side rings or lock rings of different types,
manufacturers or sizes.
•Never use cracked, bent or badly rusted parts.
•Never re-inflate flat tires on-vehicle; use the spare tire.
•Never add air until each side ring or lock ring is fully seated.
•Never hammer side ring or lock ring on a partially- or fully-inflated
tire.
Proper torque
It is important to tighten and maintain wheel and rim mounting nuts to
the proper torque. Loose nuts or over-tightened nuts can lead to
premature wear and possible failure of the wheel and/or mounting
hardware.
Changing wheel types
Consult your dealer or wheel/rim distributor before attempting any wheel
or fastener changes.
Use only the same type and style wheels and mounting hardware
to replace original parts. Failure to do so may result in an
assembly that looks fine, but does not fit together properly. This could
possibly cause wheel or fastener failures which could result in property
damage, personal injury or death.
Note:Do not attempt to mix stud-piloted wheels or fasteners with
hub-piloted wheels or fasteners.
Note:Do not change from aluminum wheels to steel wheels or
vice-versa without changing the mounting hardware required or, with
flange-nut mounting systems, changing the hub and stud assembly.
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Tire sizeLoad
rangeApproved
rim widthsAxle capacity
Front - lb.
(kg)/psi
(kPa)Rear - lb.
(kg)/psi
(kPa)
295/80R22.5 H8.2514400 (6531) /
120 (827)27760 (12591)
/ 120 (827)
9.0014780 (6704) /
120 (827)27760 (12591)
/ 120 (827)
Tire inflation information
All tires with Steel Carcass Plies (if equipped):
This type of tire utilizes steel cords in the sidewalls. As such, they
cannot be treated like normal light truck tires. Tire service, including
adjusting the air pressure, must be performed by personnel trained,
supervised and equipped according to Federal Occupational Safety and
Health Administration (OSHA) regulations. For example, during any
procedure involving tire inflation, the technician or individual must
utilize a remote inflation device, and ensure that all persons are clear of
the trajectory area.
WARNINGAn inflated tire and rim can be very dangerous if
improperly used, serviced or maintained. To avoid serious injury,
never attempt to re-inflate a tire which has been run flat or seriously
under-inflated without first removing the tire from the wheel assembly
for inspection. Do not attempt to add air to tires or replace tires or
wheels without first taking precautions to protect persons and
property.
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