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
are not slipping. The differential must not be locked when the vehicle is
traveling down steep grades and traction is minimal.
Note: Never use the differential lock at vehicle speeds above 25 mph (40
km/h).
Note: The driver-controlled differential lock function will vary with some
transmissions.
• Vehicles equipped with an Allison 3000 Series transmission: The
differential lock and differential lock light will automatically disengage
at speeds above 25 mph (40 km/h). The differential lock will remain
off until either the vehicle is restarted or the differential lock switch is
turned off then back on.
• Vehicles equipped with a 5–speed, 6–speed or 7–speed manual:
The differential lock and differential lock light will automatically
disengage at speeds above 25 mph (40 km/h). The differential lock
will remain off until either the vehicle is restarted or the differential
lock switch is turned off then back on.
Axle conversions
It is not recommended, or approved, for axle conversions to be
performed. However, it is understood that, on occasion, aftermarket
2007 F-650/750 (f67)
Supplement
USA (fus)
Driving
131
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.
2007 F-650/750 (f67)
Supplement
USA (fus)
Driving
132
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
2007 F-650/750 (f67)
Supplement
USA (fus)
Driving
133
Note:Do not exceed the GVWR or the GAWR specified on the
certification label.
Towing trailers beyond the maximum recommended gross trailer
weight exceeds the limit of the vehicle and could result in
engine damage, transmission damage, structural damage, loss of vehicle
control, vehicle rollover and personal injury.
Model Maximum
GVWR - lb.(kg) Maximum
GCWR - lb. (kg)*
F-650 Regular/Super/Crew Cab 26000 (11793) 40000 (18143)
F-750 Regular/Super/Crew Cab 30000 (13608) 45000 (20412)
F-750 Regular/Super/Crew Cab 33000 (14969) 60000 (27216)
* Figures shown are the maximum available for each model. Actual
ratings may be less, depending on your transmission. Check with your
sales consultant for the exact rating on your vehicle.
Preparing to tow
Use the proper equipment for towing a trailer and make sure it is
properly attached to your vehicle. See your dealer or a reliable trailer
dealer if you require assistance.
Hitches
Do not use hitches that clamp onto the vehicle’s bumper or attach to the
axle. You must distribute the load in your trailer so that 10–15% of the
total weight of the trailer is on the tongue.
Safety chains
Always connect the trailer’s safety chains to the frame or hook retainers
of the vehicle hitch. To connect the trailer’s safety chains, cross the
chains under the trailer tongue and allow slack for turning corners.
If you use a rental trailer, follow the instructions that the rental agency
gives to you.
Do not attach safety chains to the bumper.
Trailer brakes
Electric brakes and manual, automatic or surge-type trailer brakes are
safe if installed properly and adjusted to the manufacturer’s
specifications. The trailer brakes must meet local and Federal
regulations.
2007 F-650/750 (f67)
Supplement
USA (fus)
Driving
136
•The trailer tongue weight should be 10–15% of the loaded trailer
weight.
• If you will be towing a trailer frequently in hot weather, hilly
conditions, at GCW, or any combination of these factors, consider
refilling your rear axle with synthetic gear lube if not already so
equipped. Refer to Lubricant specifications in theMaintenance and
Specifications chapter for the lubricant specification. Remember that
regardless of the rear axle lube used, do not tow a trailer for the first
500 miles (800 km) of a new vehicle, and that the first 500 miles (800
km) of towing be done at no faster than 70 mph (112 km/h) with no
full throttle starts.
• After you have traveled 50 miles (80 km), thoroughly check your
hitch, electrical connections and trailer wheel lug nuts.
• To aid in engine/transmission cooling and A/C efficiency during hot
weather while stopped in traffic, place the gearshift lever in P (Park)
(if available on your automatic transmission) or N (Neutral) (manual
transmissions and automatic transmissions withou taP[Park]
position).
• Vehicles with trailers should not be parked on a grade. If you must
park on a grade, place wheel chocks under the trailer’s wheels.
FIFTH WHEEL OPERATION
Failure to follow the fifth wheel manufacturer’s instructions for
hooking and unhooking as well as sliding the fifth wheel could
result in an accident, personal injury or death.
When the tractor and trailer are parked unattended, the trailer
brake hand control should never be used to apply the brake,
since air may leak from the system, allowing vehicle movement,
resulting in possible property damage, personal injury or death.
Before hook-up, make sure:
• The fifth wheel jaws are fully opened.
• The fifth wheel is fully tilted back to prevent body damage when the
tractor is backed under a trailer.
• The trailer wheels are blocked and the trailer spring brakes are
adjusted and applied. Never chase a trailer.
• The brake hoses and light cords are clear of the fifth wheel.
2007 F-650/750 (f67)
Supplement
USA (fus)
Driving
138
To reduce the risk of personal injury or property damage when
manually releasing the spring brakes, be sure to block the wheels
so the vehicle cannot move once the brakes are released.
Towing the vehicle with the front wheels suspended
When it is necessary to tow a vehicle with the front wheels suspended,
extra precautions must be taken to avoid transmission or differential
damage. Proceed as follows:
•Remove the axle shafts from the axle assembly to prevent the wheels
from driving the differential and the transmission.
•The wheel hub ends must be covered to prevent loss of axle lubricant
and entrance of other contaminants. If the axle shafts are not
removed, removal of the propeller shaft is required.
Note:To avoid transmission damage, vehicles should not be towed even
a short distance without suspending rear wheels or removing the axle
shaft or propeller shaft.
Note:In the event the chassis is equipped with a tandem axle and the
vehicle is to be towed from the front, the forward rear axle may be
raised to clear the road surface and secured to the frame by chains or
U-bolts, allowing only the rear rear axle to contact the road surface. Axle
shafts must be removed from the rear rear axle assembly. The wheel hub
ends must be covered to prevent loss of axle lubricant and entrance of
contaminants. Use extreme care in securing the chains or U-bolts to
avoid possible damage to the brake lines, hoses or other components.
Towing vehicles equipped with a driver-controlled differential lock
Note:If the vehicle must be towed to a service facility with the drive
axle wheels on the ground, it is necessary to remove the axle shafts
before the vehicle is towed.
2007 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
153
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.
2007 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
155
If you must leave the engine running while checking under the
hood, do not allow any loose clothing, jewelry, hair or other
items to get near moving engine components or possible personal
injury may occur.
To open the hood:
1. Set the parking brake, shift into N (Neutral) (automatic transmission)
or 1 (First) (manual transmission) and turn the engine off.
2. Lift upward on the bottom of
each latch.
3. Pull the bottom of each latch
away from the fender.
2007 F-650/750 (f67)
Supplement
USA (fus)
Maintenance and Specifications
174