tires FORD MUSTANG 2003 Owner's Guide

DIAGNOSIS AND TESTING
Wheels And Tires
Inspection and Verification
WARNING: A vehicle equipped with a Traction- Lok® differential will always have both
wheels driving. If, while the vehicle is being serviced, only one wheel is raised off the ground
and the rear axle is driven by the engine, the wheel on the ground could drive the vehicle off
the stand or jack. Be sure both rear wheels are off the ground.
WARNING: Never run the engine with one wheel off the ground, for example, when
changing a tire. The wheel(s) resting on the ground could cause the vehicle to move.
WARNING: Do not balance the wheels and tires while they are mounted on the vehicle.
Possible tire disintegration or differential failure could result, causing personal injury and
extensive component damage. Use off- vehicle wheel and tire balancer only.
Be sure to follow the warnings when carrying out inspection and verification.
Road Test
Verify the customer concern by carrying out a road test on a smooth road. If any vibrations are
apparent, refer to Section 100 - 04 .
To maximize tire performance, inspect for signs of incorrect inflation and uneven wear, which may
indicate a need for balancing, rotation, or front suspension alignment.
Correct tire pressure and driving techniques have an important influence on tire life. Heavy cornering,
excessively rapid acceleration and unnecessary sharp braking increases tire wear.
Replacement tires must follow the recommended:
ztire sizes.
z speed rating.
z load range.
z tire construction type.
Use of any other tire size or type can seriously affect:
zride.
z handling.
z speedometer/odometer calibration.
z vehicle ground clearance.
z tire clearance between the body and chassis.
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z
wheel bearing life.
z brake cooling.
New wheels need to be installed when vehicle's wheels:
zare bent.
z are cracked.
z are dented.
z are heavily corroded.
z are leaking.
z have elongated wheel hub bolt holes.
z have excessive lateral or radial runout.
Wheel and tire assemblies are attached by six wheel nuts.
It is mandatory to use only the tire sizes recommended on the tire chart attached to the vehicle. Larger
or smaller tires can damage the vehicle, affect durability, and require changing the speedometer
calibration. Make sure wheel size and offsets match those recommended for the tire in use. 1. Inspect for signs of uneven wear that may indicate a need for balancing, rotation, front suspension alignment, damaged tie- rod, or steering components.
2. Check tires for: zcuts.
z stone bruises.
z abrasions
z blisters.
z embedded objects.
3. Tread wear indicators are molded into the bottom of the tread grooves. Install a new tire when the indicator bands become visible.
Symptom Chart Symptom Chart Condition
Possible Sources Action
z Tires show
excess wear on
edge of tread z
Underinflated tires. zADJUST air pressure
in tires.
z Vehicle overloaded. zRETURN vehicle.
NOTIFY customer of
overload condition.
z High- speed cornering. zRETURN vehicle.
NOTIFY customer of
cause of condition.
z Incorrect ride height. zSET ride height.
z Incorrect wheel alignment. zSET alignment to
specification. REFER Klj . 2 ba
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to
Section 204 - 00 .
z Incorrect tire rotation
intervals. z
ADVISE customer of
condition. ROTATE
tires.
z Tires show
excess wear in
center of tread z
Tires overinflated. zADJUST air pressure.
z Other excessive
tire wear
problems z
Incorrect tire rotation
intervals. z
ADVISE customer of
condition. ROTATE
tires.
z Incorrect tire pressure. zADJUST pressure.
z Loose or leaking shock
absorbers. z
TIGHTEN or INSTALL
new shock absorbers
as necessary.
z Incorrect wheel alignment. zSET alignment to
specification. REFER
to Section 204 - 00 .
z Loose, worn or damaged
suspension components. z
REFER to Section 204 - 00 .
z Wheel and tire assembly
out of balance. z
BALANCE wheel and
tire assembly.
z Excessive lateral or radial
runout of wheel. z
REFER to Section 100 - 04 .
z Wobble or
shimmy z
Damaged wheel bearings. zREFER to Section 204 - 00 .
z Loose or damaged
suspension components. z
REFER to Section 204 - 00 .
z Bent wheel. zINSTALL a new wheel
as necessary.
z Damaged tire. zINSTALL a new tire as
necessary.
z Loose wheel nuts. zTIGHTEN to
specification.
z High- speed
shake z
Wheel hub face/pilot/bolt
circle runout.
z Tires/wheels.
z Wheel bearings.
z Suspension/steering
linkage.
z Engine.
z Transmission.
z Brake discs/imbalance. z
REFER to Section 100 - 04 .
z Vehicle vibration zDriveline — engine.
z Tires. z
REFER to Section 100 - 04 . Klj . 3 ba
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GENERAL PROCEDURES
Wheel Leaks
WARNING: Wheel repairs that use welding or peening are not approved. An inner tube is
not an acceptable repair for leaking wheels or tires.
If the air pressure in a tire mounted on an aluminum wheel is found to be low, perform the
following procedure before considering installation of a new wheel.
1. Remove the tire and wheel assembly, and inspect the wheel for structural damage. If none exists, go to Step 2. If the wheel is damaged, install a new wheel.
2. With the tire mounted on the wheel, locate the air leak using a water bath or equivalent method, and mark the location. Check the complete wheel for possible additional leaks. When leaks are
marked, dismount the tire marking valve location on the tire for correct indexing.
3. On the tire side of the wheel, thoroughly clean the leaking area with an appropriate choke cleaner or use sandpaper of approximately 80- grit to remove all contamination. Using the
sandpaper, score the surface of the leaking area to improve adhesion of the sealer. If the valve
stem is close to the area, remove it.
4. Use a clean cloth to remove all cleaner or sanding dust.
5. NOTE: Do not use a torch containing oxyacetylene.
Heat the prepared area with a Heat Gun or a propane torch until aluminum wheel repair
compound flows. Apply the hot melt material over the prepared area using a liberal flow and
wiping action. Repair is most effective when heat is applied to the brake side of the rim, and the
sealer is melted by heat in the metal.
6. Apply only enough heat to melt the sealer, then remove the heat source. After repairing the leak, allow the wheel to cool until it can be handled safety.
7. CAUTION: Use caution when mounting the tire so as not to damage the sealer.
Index and assemble the tire and wheel. Inflate the tire to the recommended pressure as
indicated on the tire pressure decal.
8. Repeat Step 2 to verify repair.
9. When the repair is completed, balance the assembly and install it on the vehicle.
SECTION 204-
04: Wheels and Tires 2003 Mustang Workshop Manual Material
Item Specification
Professional Choke and
Linkage Cleaner
F8AZ-
19520- AB WSS-
M14P10-
B Aluminum Wheel Repair
Compound ESA-
M4G280-
A Klj . 1 ba
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REMOVAL AND INSTALLATION
Wheel And Tire
Removal
1. CAUTION: Do not use heat to loosen a seized wheel nut (1012). Heat can damage
the wheel and wheel bearings.
NOTE: To avoid damage or scratching to the center cap, place facing up when removed.
Loosen the wheel nuts. 1. NOTE: To avoid wheel damage, do not twist wrench when removing center cap.
Remove the center cap, if equipped.
2. Loosen, but do not remove, the wheel nuts.
2. CAUTION: Never use the differential housing as a lifting point.
Raise the vehicle until the tire clears the ground. For additional information, refer to Section 100 - 02 .
3. CAUTION: Do not use heat to loosen a seized wheel because heat can shorten the
life of the wheel and damage the wheel bearings. If the wheel cannot be removed by
hand, use a wheel puller to remove the seized wheel.
Remove the wheel and tire assembly.
zRemove the wheel nuts.
z Remove the wheel and tire.
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Inspection and Verification
Certain axle noise or vibration symptoms are also common to the engine, transmission, wheel
bearings, tires, and other parts of the vehicle. For this reason, be sure that the cause of the trouble is
in the axle before disassembling, adjusting or repairing the axle. Refer to
Section 100 - 04 .
Certain driveshaft vibration symptoms are common to the front engine accessory drive (FEAD), the
engine, transmission or tires. Be sure the cause of the concern is the driveshaft before repairing or
installing a new driveshaft. Refer to Section 100 - 04 .
Certain symptoms may be caused by Traction- Lok® differentials (4026). Check the vehicle certification
label and axle identification tag to determine the type of differential. Refer to Section 100 - 01 .
Noise Acceptability
NOTE: A gear-driven unit will produce a certain amount of noise. Some noise is acceptable and
audible at certain speeds or under various driving conditions such as a newly paved blacktop road.
Slight noise is not detrimental to the operation of the axle and is considered normal.
With the Traction- Lok® differential axle, slight chatter noise on slow turns after extended highway
driving is considered acceptable and has no detrimental effect on the locking axle function.
Universal Joint (U- Joint) Inspection
Place the vehicle on a frame hoist and rotate the driveshaft (4602) by hand. Check for rough operation
or seized U- joints. Install a new U- joint if it shows signs of seizure, excessive wear, or incorrect
seating. Refer to Section 205 - 01 .
Analysis of Leakage
Clean up the leaking area enough to identify the exact source. An axle leak can be caused by the
following. zAxle lubricant level is too high.
z Worn or damaged axle shaft seals or differential seals.
z Differential housing is cracked.
z Flange yoke seat is worn or damaged.
z Pinion flange is scored or damaged.
z Axle cover is not sealed.
z Vent is plugged. Klj . 2 ba
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Repair the axle as necessary. Make sure the axle lubricant is at the correct level. Refer to
Specifications in this section.
Axle Vent
NOTE:
If a plugged vent cannot be cleared, install a new one.
A plugged vent will cause excessive seal lip wear due to internal pressure buildup. If a leak occurs,
check the vent. Make sure the vent hose is not kinked. Remove the hose from the vent nipple and
clear the hose of any foreign material. While the hose is removed, pass a length of mechanics wire in
and out of the vent to clean it. Connect the hose when done.
Flange Yoke Seal
Leaks at the axle drive pinion seal originate for the following reasons:
zSeal was not correctly installed.
z Poor quality seal journal surface.
Any damage to the seal bore (dings, dents, gouges, or other imperfections) will distort the seal casing
and allow leakage past the outer edge of the axle drive pinion seal.
The axle drive pinion seal can be torn, cut, or gouged if it is not installed carefully. The spring that
holds the axle drive pinion seal against the pinion flange may be knocked out and allow leakage past
the lip.
The rubber lips can occasionally become hard (like plastic) with cracks at the oil lip contact point. The
contact point on the pinion flange may blacken, indicating excessive heat. Marks, nicks, gouges, or
rough surface texture on the seal journal of the pinion flange will also cause leaks.
When a seal leak occurs, install a new seal and check the vent and the vent hose to make sure they
are clean and free of foreign material.
Axle Shaft Seals
Axle shaft oil seals are susceptible to the same kinds of damage as axle drive pinion seals if incorrectly
installed. The seal bore must be clean and the lip handled carefully to avoid cutting or tearing it. The
axle shaft journal surface must be free of nicks, gouges, and rough surface texture.
Differential Seals
Refer to Section 205 - 02A or
Section 205 - 02B .
Analysis of Vibration WARNING: A vehicle equipped with a Traction- Lok® differential will always have both
wheels driving. If only one wheel is raised off the floor and the rear axle is driven by the engine,
the wheel on the floor could drive the vehicle off the stand or jack. Be sure both rear wheels are
off the floor.
Few vibration conditions are caused by the rear axle. On a vibration concern, follow the diagnosis
procedure in Section 100 - 04 unless there is a good reason to suspect the axle.
Tires Klj . 3 ba
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WARNING: Do not balance the wheels and tires while they are mounted on the vehicle.
Possible tire disintegration/differential failure could result, causing personal injury/extensive
component damage. Use an off- vehicle wheel and tire balancer only.
Most vibration in the rear end is caused by tires or driveline angle.
Vibration is a concern with modern, high- mileage tires if they are not "true" both radially and laterally.
They are more susceptible to vibration around the limits of radial and lateral runout of the tire and
wheel assembly. They also require more accurate balancing. Wheel and tire runout checks, truing and
balancing are normally done before axle inspection. Refer to Section 204 - 04 .
Driveline Angle
Driveline angularity is the angular relationship between the engine crankshaft (6303), the driveshaft,
and the rear axle pinion. Factors determining driveline angularity include ride height, rear spring, and
engine mounts.
Driveline Angle
An incorrect driveline (pinion) angle can often be detected by the driving condition in which the
vibration occurs.
zA vibration during coastdown from 72 to 56 km/h (45 to 35 mph) is often caused by an
excessive U-joint angle at the axle (pinion nose downward).
z A vibration during acceleration, from 56 to 72 km/h (35 to 45 mph) may indicate an excessive U- joint angle at the axle (pinion nose upward). Item Description
1 Bottom of the frame
2 Engine crankshaft centerline
3 Engine angle
4 Driveshaft and coupling shaft centerline
5 Driveshaft and coupling shaft angle
6 Rear axle pinion centerline
7 Axle pinion angle Klj . 4 ba
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When these conditions exist, check the driveline angles as described in the General Procedures
portion of this section.
If the tires and driveline angle are not the cause, carry out the NVH tests to determine whether the
concern is caused by a condition in the axle. Refer to
Section 100 - 04 .
Universal Joint (U- Joint) Wear
Place the vehicle on a frame hoist and rotate the driveshaft by hand. Check for rough operation or
seized U- joints. Install a new U- joint if it shows signs of seizure, excessive wear, or incorrect seating.
Refer to Section 205 - 01 .
Wheel Hub or Axle Flange Bolt Circle Runout
NOTE: The brake discs must be removed to carry out all runout measurements.
1. Position the special tool perpendicular to the wheel hub or axle flange bolt, as close to the hub or flange face as possible. Zero the indicator to allow the pointer to deflect either way.
2. Rotate the hub or flange until the next bolt is contacted. Record the measurement and continue until each bolt is checked. The difference between the maximum and minimum contact readings
will be the total wheel hub or axle flange bolt pattern runout. The runout must not exceed 0.38
mm (0.015 inch).
Pilot Runout
1. Position the special tools as close to the hub or axle flange face as possible. Zero the indicator to allow the pointer to deflect either way.
2. Rotate the hub or flange one full turn and note the maximum and minimum readings. The difference between the maximum and minimum readings will be the total pilot runout. Pilot
runout must not exceed 0.15 mm (0.006 inch).
Wheel Hub or Axle Flange Face Runout Klj . 5 ba
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NOTE:
If the axle shaft assembly is removed, check runout of the shaft itself. The forged (unmachined)
part of the shaft is allowed to have as much as 3.0 mm (0.120 inch) runout. This alone will not cause a
vibration condition.
1. Position the special tool on the wheel hub or axle flange face, as close to the outer edge as possible. Zero the indicator to allow the pointer to deflect either way.
2. Rotate the hub or flange one full turn and note the maximum and minimum readings. The difference between the maximum and minimum readings will be the total face runout. The
runout must not exceed 0.127 mm (0.005 inch).
Drive Pinion Stem and Pinion Flange
Check the pinion flange runout when all other checks have failed to show the cause of vibration.
One cause of excessive pinion flange runout is incorrect installation of the axle drive pinion seal.
Check to see if the spring on the seal lip has been dislodged before installing the ring gear and pinion.
Axle Noise
NOTE: Before disassembling the axle to diagnose and correct gear noise, eliminate the tires, exhaust,
trim items, roof racks, axle shafts and wheel bearings as possible causes. Follow the diagnostic
procedures in Section 100 - 04 .
The noises described as follows usually have specific causes that can be diagnosed by observation as
the unit is disassembled. The initial clues are the type of noise heard during the road test.
Gear Howl and Whine
Howling or whining of the ring gear and pinion is due to an incorrect gear pattern, gear damage or
incorrect bearing preload.
Bearing Whine
Bearing whine is a high- pitched sound similar to a whistle. It is usually caused by worn/damaged
pinion bearings, which are operating at driveshaft speed. Bearing noise occurs at all driving speeds.
This distinguishes it from gear whine which usually comes and goes as speed changes.
As noted, pinion bearings make a high- pitched, whistling noise, usually at all speeds. If however there
is only one pinion bearing that is worn/damaged, the noise may vary in different driving phases. If
pinion bearings are scored or damaged or there is a specific pinion bearing noise, new pinion bearings
must be installed. A worn/damaged bearing will normally be obvious at disassembly. Examine the
large end of the rollers for wear. If the pinion bearings original blend radius has worn to a sharp edge, a new pinion bearing must be installed. Klj . 6 ba
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