2003 FORD MUSTANG tire type

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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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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crayon or chalk.
6. While holding the crayon or chalk against the tire, rotate the wheel slowly in the opposite direction until the feeling of driving the rear axle is encountered again.
7. Measure the length of the crayon or chalk mark on the tire. zIf the length of the mark is 25.4 mm (1 inch) or less, the rear axle backlash is within
allowable limits.
z If the chalk mark is greater than 25.4 mm (1 inch), check for these conditions:
„Elongation of the differential pinion shaft and holes in the differential case (4204).
„ Missing differential pinion thrust washer (4230) or differential side gear thrust
washer (4228).
„ Galling of the differential pinion shaft (4211) and bore.
„ Excessive ring gear and pinion backlash. Follow the procedure for the type of rear
axle to check backlash.
Axle Shaft Bearing Noise
Axle bearing shaft noise is similar to gear noise and differential pinion bearing whine. Axle shaft
bearing noise will usually distinguish itself from gear noise by occurring in all driving modes (drive,
coast, and float), and will persist with the transmission in NEUTRAL while the vehicle is moving at the
speed in which the concern is occurring. If the vehicle makes this noise, remove the suspect axle
shaft, install a new bearing and a new axle seal. Re- evaluate the vehicle for noise before removing any
internal components.
Bearing Rumble
Bearing rumble sounds like marbles being tumbled. This condition is usually caused by a
worn/damaged wheel bearing. The lower pitch is because the wheel bearing turns at only about one-
third of the driveshaft speed. Wheel bearing noise also may be high- pitched, similar to gear noise, but
will be evident in all four driving modes.
Symptom Chart
Symptom Chart Condition
Possible Sources Action
z Traction- Lok®
does not work in
snow, mud or on
ice z
Differential. zCARRY OUT the Traction-
Lok® Differential Operation
Check in this section. REPAIR
as necessary. REFER to
Section 205 - 02A or
Section 205 - 02B .
z Lubricant leaking
from the pinion
seal, axle shaft oil
seals z
Vent.
z Damage in the
seal contact area
or damaged or
worn seal. z
CLEAN the axle housing vent.
z INSTALL a new seal if
damage is found.
z Differential side
gears/pinion
gears are scored z
Insufficient
lubrication. z
INSTALL new gears. REFER
to Section 205 - 02A or
Section 205 - 02B . FILL the axle to
specification.
z Incorrect or
contaminated z
INSTALL new gears. REFER
to Section 205 - 02A or
Section Klj . 10 ba
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Component Tests
Driveline Vibration
An analysis of driveline vibration can also be conducted using the Vibration Analyzer; follow the
manufacturer's directions.
Driveline vibration exhibits a higher frequency and lower amplitude than does high-
speed shake.
Driveline vibration is directly related to the speed of the vehicle and is usually noticed at various speed
ranges. Driveline vibration can be perceived as a tremor in the floorpan or is heard as a rumble, hum,
or boom. Driveline vibration can exist in all drive modes, but may exhibit different symptoms depending
upon whether the vehicle is accelerating, decelerating, floating, or coasting. Check the driveline angles
if the vibration is particularly noticeable during acceleration or deceleration, especially at lower speeds.
Driveline vibration can be duplicated by supporting the axle upon a hoist or upon jack stands, though
the brakes may need to be applied lightly in order to simulate road resistance.
1. Raise the vehicle promptly after road testing. Use a twin- post hoist or jack stands to prevent tire
flat- spotting. Engage the drivetrain and accelerate to the observed road test speed to verify the lubricant type.
205 - 02B . CLEAN and
REFILL the axle to
specification.
z Axle overheating zLubricant level too
low. z
CHECK the lubricant level.
FILL the axle to specification.
z Incorrect or
contaminated
lubricant type. z
INSPECT the axle for
damage. REPAIR as
necessary. CLEAN and
REFILL the axle to
specification.
z Bearing preload
adjusted too tight. z
CHECK the ring and pinion for
damage. INSPECT the ring
and pinion wear pattern.
ADJUST the preload as
necessary.
z Excessive gear
wear. z
INSPECT all the axle gears
for wear or damage. INSTALL
new components as
necessary.
z Incorrect ring gear
backlash. z
INSPECT the ring gear for
scoring. INSPECT the ring
and pinion wear pattern.
ADJUST the ring gear
backlash as necessary.
z Broken gear teeth
on the ring gear
or pinion z
Overloading the
vehicle. z
INSTALL a new ring and
pinion. REFER to Section 205 - 02A or
Section 205 - 02B .
z Axle shaft broken zOverloading the
vehicle. z
INSTALL a new axle shaft.
REFER to Section 205 - 02A or
Section 205 - 02B .
z Misaligned axle
shaft tube. z
INSPECT the axle for
damage. CHECK axle shaft
tube alignment. INSTALL a
new axle shaft. REFER to
Section 205 - 02A or
Section 205 - 02B . Klj . 11 ba
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z
Do not drop assembled halfshafts. The impact will cut the boots from the inside without
evidence of external damage.
z Inspect all machined surfaces and splines for damage.
Wheel and Tire Balancing, Rear
WARNING: Do not balance the rear wheels and tires while mounted on the vehicle.
Possible tire disintegration, differential or halfshaft failure can result, causing personal injury
or extensive component damage. Use an off- vehicle wheel and tire balancer only.
Hoisting
CAUTION: Use a frame- contact hoist only. Vehicle or component damage can result if
other types of hoists are used.
Never raise the vehicle using the halfshafts as lift points.
Undercoating and Rustproofing
During undercoating and rustproofing procedures, protect the boots from the coating materials.
Foreign materials on the rubber boots will cause extreme advanced wear. Klj . 3 ba
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not machine a new brake disc.
7. For vehicles with a two- piece hub and brake disc assembly:
z Match-mark before disassembly.
z Remove the brake disc.
z Using a die grinder with a mild abrasive (Scotch Brite® type), remove any rust or
corrosion from the hub and brake disc mounting surfaces.
z Align the match- marks and reinstall the brake disc on the hub.
8. CAUTION: Do not use a bench lathe to machine brake discs.
NOTE: The depth of cut must be between 0.10 and 0.20 mm (0.004 and 0.008 inch). Lighter
cuts will cause heat and wear. Heavier cuts will cause poor brake disc surface finish.
Using on- vehicle brake lathe, machine the brake discs. Follow the manufacturer's instructions.
After machining, make sure the brake disc still meets the thickness specification.
9. Using a dial indicator, verify that the brake disc lateral runout is now within vehicle specification.
10. Remove any metal chips.
11. Remove the hub adapter.
12. Remove any remaining metal chips from the machining operation.
13. CAUTION: Do not carry out this step on rear drum- in-hat brake discs.
For vehicles with a two- piece hub and a non drum- in-hat brake disc assembly:
z Remove the brake disc from the hub.
z Remove any remaining metal chips from hub and brake disc mounting surfaces and from
the ABS sensor.
z Apply High Temperature Nickel Anti- Seize Lubricant F6AZ-9L494-AA to the mounting
surfaces.
z Using the match- marks, mount the brake disc on the hub.
14. Install the caliper and check brake operation.
Symptom Chart Symptom Chart
Condition
Possible Sources Action
z The Brakes Pull or
Drift z
Tire air pressure.
z Wheel alignment.
z Brake pads.
z Brake components.
z Suspension
component. z
Go To Pinpoint Test A .
z The Red Brake
Warning Indicator Is z
Instrument cluster.
z Circuit. z
Go To Pinpoint Test B . Klj . 4 ba
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PINPOINT TEST C: BRAKE LOCKUP DURING LIGHT BRAKE PEDAL
FORCE z
Is the resistance greater than 10,000 ohms? No
REPAIR the ground short in
circuit 128 (VT/YE). TEST the
system for normal operation.
B6 CHECK DAYTIME RUNNING LIGHTS (DRL) MODULE
z
Disconnect: DRL Module C1030.
z Measure the resistance to ground at C124- 2.
z Is the resistance greater than 10,000 ohms? Yes
REPAIR the DRL module. TEST
the system for normal operation.
No
REPAIR the ground short in
circuit 22 (LB/BK) or 977
(VT/WH). TEST the system for
normal operation.
Test Step Result / Action to Take
C1 INSPECT THE TIRES
z
Inspect the tires for uneven or excessive
wear, correct pressure, correct size and
type.
z Are the tires OK? Yes
GO to
C2 .
No
CORRECT as necessary. RETEST for
normal operation. C2 CHECK THE BRAKE CALIPER
COMPONENTS z
Inspect the brake pads and brake discs for
wear, damage, contamination and correct
installation.
z Are the brake components OK? Yes
GO to
C3 .
No
CORRECT as necessary. RETEST for
normal operation. C3 CHECK THE PROPORTIONING VALVE
z
Install the gauges from the ABS brake and
pressure test kit on one front and one rear
bleeder screw.
z Apply 6895 kPa (1000 psi) to the front
brake system.
z Is the pressure in the rear system 3516- Yes
INSPECT the disc brake calipers and
INSTALL new calipers as necessary.
RETEST for normal operation.
No Klj . 9 ba
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Brake Pressure Control Valve
The brake pressure control valve proportions the pressure to the rear brakes.
zWhen the brake pedal is applied, brake fluid pressure passes through the proportioning valves
to the rear brake system until the valve split point is reached.
z Above its split point, the proportioning valve begins to reduce the hydraulic pressure to the rear
brakes, creating a balanced braking condition between the front and rear brakes.
Brake Tubes and Hoses CAUTION: Never use copper tubing. It is subject to fatigue, cracking and corrosion which
could result in brake tube failure.
Steel tubing is used throughout the brake hydraulic system. All brake tube fittings must be correctly
double flared to provide strong leakproof connections. When bending the tubing to fit the underbody or
rear axle contours, be careful not to kink or crack the tube.
If a section of brake tube is damaged, the entire section must be removed and a new tube of the same
type, size, shape and length installed.
When replacing hydraulic brake tubing, hoses, or connectors, tighten all connections securely. After
installation, bleed the brake system. For additional information, refer to Section 206 - 00 . Klj . 3 ba
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