FORD F750 2011 12.G Owners Manual

SUSPENSION INSPECTION
Note:Do not adjust air suspension height to any setting other than the
specified setting. Altering the height setting will change 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 lube oil change intervals.
Periodically:
•Check condition of spring leaves for evidence of fatigue, bending or
breakage.
•Check condition of suspension mounting brackets and bushings.
•Check that torque rod mounting fasteners are tight.
•Check to be sure the suspension alignment is maintained at all times.
•Check U-bolts after the chassis has been operating under load for
1,000 miles (1,600 km) or six months, whichever comes first, the
U-bolt nuts must be re-torqued. The U-bolt nuts thereafter must be
re-torqued every 36,000 miles (58,000 km). The U-bolt and nut
threads and seats should be cleaned and lubricated to ensure a “like
new” condition when re-torquing.
Note:See theU-bolt nut torquechart later in this section.
Supporting your vehicle for service
When performing service repairs on your vehicle, first prepare the
vehicle by doing the following:
1. Park the vehicle on a level concrete floor.
2. Set the parking brake and block the wheels to prevent the vehicle
from moving.
3. Select a jack with a rated capacity sufficient to lift and hold up the
vehicle.
4. Raise the vehicle with the jack applied to the axle(s). DO NOT use the
bumper as a lifting point.
5. Support the vehicle with floor stands under the axle(s). If the axle or
the suspension are being serviced, support the vehicle with floor stands
under the frame side-members, preferably between the axles.
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WARNING:Do not use a jack when working under a vehicle. It
may give way, causing the vehicle to fall and result in property
damage, personal injury or death. Always use floor stands to support
the vehicle.
FRAME AND TOW HOOKS
Your vehicles chassis is manufactured with frame rails of either HSLA
steel or heat-treated steel. Each must be handled in a specific manner to
ensure maximum service life. Before attempting frame repair or
modification, consult the service manual or your dealer.
It is important, particularly on vehicles where the tow hooks are used
frequently, to inspect the front and rear tow hooks for damage or a loose
mounting.
SPRING U-BOLT CHECKS
Check U-bolt nuts and re-torque every 36,000 miles (58,000 km) after
initial 1,000 miles (1,600 km) re-torque. The U-bolt and nut threads and
seats should be cleaned and lubricated to ensure peak condition when
re-torqued.
U-bolt nut torque
Suspension ft-lb N•m
Front axle – 8500 lb (3856 kg) 180-200 244-271
Front axles – 10000 lb (4536 kg) and higher 260-300 353-407
Rear axle with multi-leaf 260-300 353-407
Rear axle with IROS air suspension 370-400 502-542
Rear axle with Hendrickson air suspension 400–450 542–610
See air suspension U-bolt re-torquing and installation information below.
Air suspension U-bolt checks and re-torquing procedures
1. Inspect the threads of the U-bolt and nut for rust and debris. Clean
the threads if contaminated.
2. Using a torque wrench, determine if any nuts can be turned with a
force below the specified torque.
3. Using the lowest discovered torqued nut as a starting point, retighten
the nuts using the sequence listed underAir suspension U-bolt and
U-bolt nut installation.
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Air suspension U-bolt and U-bolt nut installation
1. Inspect the threads of the U-bolt and nut for rust and debris. Clean
the threads if contaminated.
2. Install the U-bolts and nuts and torque the nuts to seat the cap flat
which is about 18 ft-lb (25 N•m) using a diagonal pattern. Use the same
diagonal pattern for each of the following U-bolt nut re-torque steps.
3. Tighten U-bolt nuts in increments of 74 ft-lb (100 N•m) until
tightened to final torque for the particular suspension.
DRIVESHAFT
At the regular lubrication interval, check the universal joints for any
evidence of wear or looseness. Should driveshaft vibrations occur, stop
the vehicle immediately to avoid possible hazardous consequences or
damage to other components.
REAR AXLE LUBRICANT
Refer to theScheduled Maintenance Guidechapter for rear axle
lubricant level checks and lubricant change intervals.
Your rear axle may be filled with an optional synthetic lubricant which
allows the use of extended service intervals. A tag on the filler plug will
identify the use of the synthetic lubricant.
Use only a lubricant that meets manufacturer specifications (refer to
Lubricant specificationsin this chapter).
Use of a non-approved rear axle lubricant may cause internal axle
component damage.
Checking the rear axle lubricant level
1. Park the vehicle on level ground.
2. Set the parking brake and shift into N (Neutral) (automatic
transmission) or 1 (First) (manual transmission) and turn the engine off.
3. Clean any dirt from around the rear axle filler plug.
4. Remove the filler plug and inspect the lubricant level.
5. The lubricant level should be up to the bottom of the filler plug
opening.
6. If necessary, add enough lubricant through the filler plug opening so
that the lubricant level is at the bottom of the opening.
7. Clean and install the filler plug securely.
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Draining and refilling the rear axle lubricant
1. Drain the rear axle while the lubricant is warm.
2. Park the vehicle on level ground.
3. Set the parking brake and shift into N (Neutral) (automatic
transmission) or 1 (First) (manual transmission) and turn the engine off.
4. Clean any dirt from around the rear axle filler and drain plugs.
5. Remove the filler and drain plugs and drain the lubricant into a
suitable container. Dispose of all used automotive fluids in a responsible
manner following your local authorized standards.
6. Clean and install the drain plug securely.
7. Add enough lubricant through the filler plug opening so that the
lubricant level is up to the bottom of the opening.
8. Clean and install the filler plug securely.
WHEELS
General
Wheel bearings should be inspected, lubricated and adjusted at regular
intervals. This is especially important if operating in deep sand, mud, or
water. Refer toLubricant specificationsin this chapter.
When installing wheel balance weights, they must be mounted on the
dome-side of the wheel only. Failure to do so may result in loss of wheel
weight and/or damage to brakes or wheels.
Important:Remember to replace the wheel air valves when the road
tires are replaced at the end of their useful life.
Oil-lubricated front wheel bearings
During normal vehicle duty cycle, the lube and air inside the hub/wheel
cavity expands and if not vented, causes pressure build-up that could
cause accelerated seal wear.
There are two venting methods:
•a slit or small hole in the rubber check vent or
•the window
You can use either of these methods to prevent pressure build-up.
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Normal maintenance
Over a period of time, if not routinely cleaned, a slight film of oil can
collect dirt around the rubber fill plug and face, which could appear to
be a leak. Routine cleaning ensures that the lube level can be easily
observed through the clear window as intended. In situations where the
window is clean on the outside but discolored on the inside, the lube
level may be checked by inserting a finger through the rubber check
vent hole.
The specified lube level for a clear window type hubcaps is from the
minimum line to + 5/16 inch above the minimum line.
If the lube level should suddenly drop dramatically below the minimum
level, see theWorkshop Manualfor diagnostic procedure.
Installation, tightening and alignment
When installing wheels, be certain that the threads on studs and nuts are
clean to permit correct torque. The mounting surfaces of rims, wheels,
spacer rings and clamps must be free of dirt, rust, lubricants or damage.
Use a wire brush to clean the mounting contact surfaces. Do not use
lubricant on threads.
After the rim or wheel has been properly tightened, it should be checked
for alignment. Rotate the wheel with a piece of chalk attached to a
steady, firm surface, and placed to just barely clear the outside surface of
the tire bead seat. This procedure will point out the high spot. A high
spot does not necessarily mean that the lug nuts have been unevenly
tightened. This condition or misalignment could be caused by a bent
wheel.
Use the following installation procedure:
1. Slide inner rear or front tire and wheel in position over studs and push
it back as far as possible. Use care so that the threads on studs are not
damaged.
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Disc wheel with flange nuts (hub-piloted)
Front wheel mounting of flange nut
system
1. Flange nut
2. Wheel(s)
3. Brake drum
4. Wheel stud (22 mm)
5. Wheel hub
2. Position the outer rear tire and wheel in place over the studs and
push it back as far as possible. Use care so that the threads on studs are
not damaged.
Rear wheel mounting of flange nut
system
1. Flange nut
2. Wheel(s)
3. Brake drum
4. Wheel stud (22 mm)
5. Wheel hub
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Aluminum rear disc wheel with flange nuts (hub-piloted)
1. Flange nut
2. Wheel(s)
3. Brake drum
4. Wheel stud (22 mm)
5. Wheel hub
6. Wheel locator pad
Note for aluminum wheels:Prior to re-installing rear aluminum
hub-piloted wheels, clean each wheel locator pad on the hub from all
dirt, rust and foreign material. Apply a light coat of chassis grease,
never-seize or disc brake corrosion control grease, only to the wheel
locator pad.
3. Run the nuts on the studs until they contact the wheel(s). Rotate the
wheel assembly a half-turn to permit the parts to seat.
4. Draw up the nuts alternately following the crisscross sequence
illustrated under the following wheel tightening sequence illustrations.
Do not fully tighten the nuts. This will allow uniform seating of the nuts
and ensure even face-to-face contact of the wheel and hub.
1
6
5
4
32
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Wheel tightening sequence:
8–lug wheel
10–lug wheel
5. Continue tightening the nuts to the torque specifications in the torque
chart using the same crisscross sequence shown.
6. After operating the vehicle approximately 50 miles (80 km), check the
nuts for tightness. Some natural seating of parts may be encountered
and the torque on the nuts will drop. Retighten all nuts to specifications.
Once a week, inspect and retighten the wheel stud nuts.
Note:When installing the tire and rim assembly on disc-brake equipped
axles, make sure the tire valve stem clears the brake caliper. The use of
a tire manufacturer’s stem forming tool is the only acceptable method of
obtaining clearance when necessary.
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.
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WARNING: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.
WHEEL NUT TORQUE
Size Nut mountingTorque
ft-lb N•m
22 mm Flange 450–500 610–678
Note:Do not use lubrication on dry threads. Where excessive corrosion
exists, a light coat of lubricant on the first three threads of the stud bolt
is permitted. Keep lubricant away from:
•Hex nut and rim clamp contact surfaces.
•Cap nut ball face and ball seat on the disc wheel.
•Flange nut washer surface and flat on the disc wheel.
TIRE INFORMATION
Inflation
WARNING:Always maintain your tires in good condition.
Frequently check and maintain correct inflation pressures as
specified by tire manufacturers. Inspect periodically for abnormal wear
patterns and repair/replace cut or broken tire casing. Always use
experienced, trained personnel with proper equipment and correct
procedures to mount or remove tires and wheels. Failure to adhere to
these warnings could result in wheel or tire malfunction, damage to
your vehicle, personal injury, or death.
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WARNING:To avoid personal injury or death, always follow
these instructions when mounting radial tires on wheels:
•Only personnel that have had proper training and experience should
mount or remove tires from rims or wheels.
•Use only heavy-duty rims or approved rims for radial tires. It may be
necessary to contact your wheel and rim distributor to determine if
your rims are approved for radial tires.
•If a tube is to be used, make sure special radial tire tubes are used
because of the increased flexing of the sidewalls on radial tires.
•Never use anti-freeze, silicones, or petroleum based lubricants when
mounting radial tires. Only an approved lubricant should be used as
an aid for mounting tires.
•Always inflate tires in a safety cage.
•Do not attempt to mix stud piloted wheels or fasteners with hub
piloted wheels or fasteners. To do so may cause premature wheel
failure resulting in property damage, personal injury, or death.
•Do not mix foreign (not made in North America) wheel mounting
parts with domestic (made in North America) parts. Many foreign
wheel components look similar to, but not exactly the same as
domestic made components. Mixing components could cause wheel
or fastener failures and result in property damage, personal injury, or
death.
•Do not change from aluminum wheels to steel wheels or vice-versa
without changing the mounting hardware where required or, in some
cases with flange nut mounting systems, changing the hub and stud
assembly. Mixing components could cause wheel or fastener failures
and result in property damage, personal injury, or death.
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.
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