2015 FORD F750 front axle

Front of vehicle
LightsVerify:
•All exterior lights illuminate and are clean
•Headlights function on high and low beam
•Reflectors are clean, unbroken and of proper
color (red on rear, amber elsewhere)
•Running lights are clean and unbroken.
Steering gearInspect for any:
•Missing or loose fasteners
•Power steering fluid leaks
•Damage to power steering hoses.
Steering linkageVerify:
•Connecting links, arms and rods are not worn
or cracked
•Joints, sockets and boot seals are not worn or
loose
•Cotter keys, nuts and bolts are not loose or
missing.
Tow hooksInspect front and rear tow hooks for damage or
loose mounting. This is particularly important on
vehicles that use them frequently.
Front suspension
SpringsInspect for leaves that may be:
•Missing
•Broken
•Shifted
•In contact with (or nearly contacting) a tire,
rim, brake drum, frame or body component.
Note:Never apply grease to spring pads.
Spring mountsInspect the following for cracks, breaks, wear,
damage and tightness:
•Spring hangers
•Bolts
•Bushings
•Axle mounting bolts
•Nuts.
Shock absorbersInspect for any:
•Cracks
•Leaks
•Missing or broken bolts or bushings.
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Towing the Vehicle with the Front Wheels Suspended
Note:To avoid transmission damage, do not tow your vehicle even a
short distance without suspending rear wheels or removing the axle
shafts or driveshaft.
Note:When towing a vehicle equipped with a tandem axle from the
front, raise the forward rear axle so it can clear the road surface and
secure it to the frame with chains or U-bolts, allowing only the rear rear
axle to contact the road surface. Remove axle shafts from the rear rear
axle assembly. Cover the wheel hub ends 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.
When it is necessary to tow a vehicle with the front wheels suspended,
take extra precautions to avoid transmission or differential damage:
•Remove the axle shafts from the axle assembly to prevent the wheels
from driving the differential and the transmission.
•Cover the wheel hub ends to prevent loss of axle lubricant and
entrance of other contaminants. If you do not remove the axle shafts,
removal of the driveshaft is required.
Towing the Vehicle with the Rear Wheels Suspended
Note:To avoid damage to the cab roof or air deflector when towing your
vehicle backward (rear wheels suspended), remove the air deflector.
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, you must lock the front wheels in the
straight-ahead position.
Vehicles equipped with a manual transmission must have at least 1.0 pint
(0.5 liter) of transmission fluid drained from the case. This prevents the
transmission fluid from entering the clutch housing and saturating the
clutch discs. Make sure to replace the transmission fluid before returning
your vehicle to service.
Towing Vehicles Equipped with a Driver-controlled Differential
Lock
Note:If you have to tow your vehicle to a service facility with the drive
axle wheels on the ground, it is necessary to remove the axle shafts
before towing your vehicle.
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Climate Control System
Have the air conditioning system checked each spring. The refrigerant
charge, cleanliness of the condenser-evaporator cores and belt condition
are essential to system performance.
When the air conditioning system is being used daily, remove the fresh
air filter (if equipped) once each season and check for things such as
dirt and lint. Replace the filter if necessary. Vehicles operating in
unusually dusty conditions may require more frequent filter inspection
and replacement.
Front Axle
Maintaining the front axle alignment to specifications is very important.
A qualified technician should check and maintain the alignment. Regular
inspections should include:
•Toe-in inspection and adjustment (if necessary), particularly with
radial tires.
•Checking for proper tightness of axle mounting U-bolt nuts, attaching
or mounting bolts and nuts.
•Checking the axle for damage, binding, worn parts and adequate
lubrication..
•Checking the kingpins for excessive wear. Also, perform this check
during other scheduled maintenance (such as tire rotation or service,
wheel bearing service and alignment). See the workshop manual for
proper procedures.
Toe-in
It is essential to maintain correct toe-in and tire pressure for optimum
tire wear.
Inspecting steer axle tires in the first 3000–10000 service miles
(5000–16000 service kilometers) generally shows 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, there can be a left-to-right steer tire tread life
differential up to 40% 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 equals
12steer axle loading).
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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.
•For proper suspension alignment. Maintain proper alignment at all
times.
•U-bolts. After the chassis has been operating under load for
1000 miles (1600 kilometers) or six months (whichever comes first),
the U-bolt nuts must be re-torqued. Re-torque the U-bolt nuts every
36000 miles (60000 kilometers) thereafter. Clean and lubricate the
U-bolt and nut threads and seats to make sure a like new condition
when re-torqueing.
Note:SeeSpring U-bolt checklater in this chapter.
Supporting Your Vehicle for Service
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.
Prepare your vehicle for service repairs by doing the following:
1. Park your vehicle on a level, concrete floor.
2. Set the parking brake and block the wheels to prevent your vehicle
from moving.
3. Select a jack with a rated capacity sufficient to lift and hold up your
vehicle.
4. Raise your vehicle with the jack applied to the axle(s). Do not use
the bumper as a lifting point.
5. Support your vehicle with floor stands under the axle(s). When
servicing the axle or the suspension, support your vehicle with floor
stands under the frame side-members, preferably between the axles.
Frame and Tow Hooks
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.
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SPRING U-BOLT CHECKS
Check U-bolt nuts and re-torque every 36000 miles (60000 kilometers)
after initial 1000-mile (1600 kilometer) re-torque. Clean and lubricate the
U-bolt and nut threads and seats to make sure they are in 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 axle – 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-torqueing and installation information below.
Air Suspension U-bolt Checks and Re-torqueing 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 you can turn any nuts with a
force below the specified torque.
3. Using the lowest discovered torqued nut as a starting point,
re-tighten the nuts using the sequence listed underAir suspension
U-bolt and U-bolt nut installation.
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.
BRAKE FLUID CHECK
WARNING:Brake fluid is toxic. If brake fluid contacts the eyes,
flush eyes with running water for 15 minutes. Seek medical
attention if irritation persists. If taken internally, drink water and induce
vomiting. Seek medical attention immediately.
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Proper tire inflation, toe-in adjustment, loads, and road speeds are
important factors governing tire mileage, steering ease and
maneuverability.
Tire Loading
WARNING:Loading tires beyond their rated capacity decreases
tire life requiring more frequent replacement of tires. Overloading
creates an unsafe condition that may result in sudden air loss from a
tire failure resulting in an accident that could cause property damage,
personal injury or death.
Note:Your GAW/GVW rating is correct at the time of your vehicle
production, and reflects the exact rating of the tires specified. When
replacing tires, make sure that the replacement tire load rating (listed in
pounds and kilograms on the tire sidewall) is the same or higher than
the tire that you are replacing. Failure to do so adversely affects
maximum load carrying capacity. Tires with the same size specification
do not always have the same load specification.
Note:The tire installed as original equipment may not be the same as
the tire specified on the DOT label, but has enough load capacity to
carry the GAW/GVW specified.
Note:Tires with the same size specification do not always have the same
load specification.
Matching Tires
Dual Tires:Dual tires should be matched using tires of equivalent size.
Do not mount tires that differ more than one-quarter inch (6
millimeters) in diameter or three-quarters inch (19 millimeters) in
circumference on the same dual wheel assembly.
Mixing:Never mix bias and radial tires on this vehicle. Never mix
different tire sizes or constructions on the same axle.
Rotation:
Rotation is always advisable:
•If there is irregular wear on the front (steering) axle tires, move to
rear position.
•In a dual assembly, reverse the position of the tires if one tire wears
much faster than its mate does.
•On the drive axle, if heel and toe wear or alternate lug wear occurs,
rotating the tires from one end of the axle to the other end of the
axle may help even out this wear.
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Rotation may not advisable:
•Front (Steering) Axle:Remove tires when tread wears down to
four–thirty seconds inch (3 millimeters) or less. Retread or rotate
worn tires to drive position. We do not recommend using retreaded
tires on steering axles.
•Rear Axles:Remove tires when tread wears down to two–thirty
seconds inch (2 millimeters).
If using a rib tire on front axle and lug or off-road type on rear axle
positions:
•Front (Steering) Axle:Replace tires at front wheels when tread is
worn to four–thirty seconds inch (3 millimeters) or less.
•Rear Axles:Remove tires when the tread wears down to two–thirty
seconds inch (2 millimeters) or less. Tires identified with the word
re-groovable molded on the sidewall can be re-grooved. There must
be a minimum of three–thirty seconds inch (2.5 millimeters) of
under-tread at the bottom of the grooves.
Wheel and Tire Balancing
Out-of-round or out-of-balance wheels or tires can cause vehicle
vibration, bounce and shimmy. Replace damaged or out-of-round wheels.
You can correct out-of-round tires and wheel assemblies by re-clocking
the tire relative to the wheel.
You should then dynamically balance the tire and wheel assembly.
Tire Wear
Radial tires can exhibit three types of normal wear patterns:
•Even
•Erosion
•Chamfer
Even wear:A sign that the tire is being properly used and maintained.
Erosion wear:Also called rolling wear, channel or river wear, erosion
wear occurs more often on free-rolling tires. This is an indication of
using the tire in a slow wearing operation. What happens is that the belt
plies are held very rigid and the tread is not allowed to distort as it
passes through the contact area. Wear only occurs at the edge of the
tread. No corrective action required. If erosion gets to be one–sixteenth
inch (2 millimeters) or more, you can rotate the tire to a drive axle.
Chamfer or shoulder wear:With tires inflated properly, this is a
normal tendency of most radial tire designs. If both inside and outside
shoulders are wearing evenly around the tire, no further action is
required. Over-inflation is not effective in correcting this effect.
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Irregular Wear:If irregular wear is present, check the axle alignment,
tire pressure, wheel balancing, shock and suspension component
condition, and wheel bearing end play.
This condition not only shortens tire life, but also adversely affects the
handling of your vehicle, which is dangerous.
Rotating tires from one wheel position to another is an often-used way to
even out many types of irregular wear or to avoid it altogether. Some of
the more effective tire rotation programs are:
•You can rotate steer tires that have developed some type of irregular
wear pattern to drive axles if using rib tires on all wheel positions.
Applying steer tires to a drive position often cleans them. You can
move them back to the steer axles or run out to re-tread stage on the
rear axle.
•Another rotation possibility for fleets with rib tires in all wheel
positions is to break in the new steer tires in the drive axle positions,
then move them to steer axles. This wears away tread rubber
relatively quickly in the early life of a tire when it is most likely to
develop an unusual wear pattern.
•You can place drive axle tires on the other end of the same axle to
reverse the direction of rotation. This is often helpful if a heel and
toe or alternate lug wear pattern has developed.
You can help minimize irregular wear by:
•Using the right inflation pressure for the load being carried.
•Maintaining proper front wheel alignment, especially toe-in, to
specifications.
•Maintaining proper tire and wheel balance.
•Maintaining shock absorbers and suspension components.
Use of Tire Chains
See the chain manufacturer’s recommendation for correct tire chain
usage, installation and removal.
WHEELS
General Information
Note:Remember to replace the wheel air valves when replacing the road
tires at the end of their useful lives.
Inspect, lubricate and adjust wheel bearings at regular intervals. This is
especially important if operating in deep sand, mud or water. See the
Capacities and Specificationschapter.
Mount wheel balance weights on the dome-side of the wheel only. Failure
to do so may result in loss of wheel weight or damage to brakes or
wheels.
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