wheel FORD MUSTANG 2003 Workshop Manual

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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NOTE:
A low-pitched rumble normally associated with a worn/damaged wheel bearing can also be
caused by tires.
A wheel bearing noise can be mistaken for a pinion bearing noise. Check the wheel bearing for a
spalled cup, and spalled/damaged rollers. Check the wheel bearing for rotating smoothness and end
play. Install a new wheel bearing if any of these concerns are detected.
If the wheel bearing is damaged, the roller surface on the axle shaft may also be damaged. Install a
new axle shaft if any damage is detected.
Chuckle
Chuckle that occurs on the coast driving phase is usually caused by excessive clearance between the
differential gear hub and the differential case bore.
Damage to a gear tooth on the coast side can cause a noise identical to a chuckle. A very small tooth
nick or ridge on the edge of a tooth can cause the noise.
Clean the gear tooth nick or ridge with a small grinding wheel. If the damaged area is larger than 3.2
mm (1/8 inch), install a new gearset.
To check the ring gear and pinion, remove as much lubricant as possible from the gears with clean
solvent. Wipe the gears dry or blow them dry with compressed air. Look for scored or damaged teeth.
Also look for cracks or other damage.
If either gear is scored or damaged badly, install a new ring gear and pinion. Klj . 7 ba
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2.
NOTE: Measure the end play with a Dial Indicator with Bracketry and not by feel.
Knock is also caused by excessive end play in the axle shafts. Up to 0.762 mm (0.030 inch) is
allowed in semi- float axles. The frequency of the knock will be less because the axle shaft
speed is slower than the driveshaft.
Clunk
Clunk is a metallic noise heard when the automatic transmission is engaged in REVERSE or DRIVE.
The noise may also occur when throttle is applied or released. It is caused by backlash somewhere in
the driveline or loose suspension components; it is felt or heard in the axle. Refer to Total Backlash
Check in this section.
Additionally, clunk may be heard upon initial drive- away. This occurs as engine torque shifts vehicle
weight, forcing changes in driveline angles, preventing the driveshaft slip- yoke from sliding on the
output shaft. To correct for this condition, lubricate the slip- yoke splines.
Total Backlash Check 1. Raise and support the vehicle. Refer to Section 100 - 02 .
2. Remove the driveshaft. Refer to Section 205 - 01 .
3. Install the special tool. zClamp a rigid bar or pipe to the tool. Clamp the other end of the bar or pipe to the frame
or a body member in order to prevent movement of the rear axle pinion flange.
4. Lower the vehicle so that one rear wheel is resting on a wheel chock to prevent it from turning. The other rear wheel will be used to measure total rear axle backlash.
5. Rotate the free wheel slowly, by hand, until the feeling of driving the rear axle is encountered. Place a mark on the side of the tire, 305 mm (12 inches) from the center of the wheel, with a Klj . 9 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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presence of the vibration. If the vibration is not evident, check the non-
driving wheels with a
wheel balancer to rule out imbalance as a possible cause. If required, balance the non- driving
wheels and repeat the road test. If the vibration is still evident, proceed to Step 2.
2. Mark the relative position of the drive wheels to the wheel nuts. Remove the wheels. Install all the nuts in the reversed position and repeat the road speed acceleration. If the vibration is gone,
refer to the tire and wheel runout procedure in Section 204 - 04 . If the vibration persists, proceed
to Step 3.
3. Inspect the driveshaft for signs of physical damage, missing balance weight, undercoating, incorrect seating, wear and binding universal joints. Clean the driveshaft and install new
universal joints or a new driveshaft if damaged. Check the index marks (paint spots) on the rear
of the driveshaft and pinion flange. If these marks are more than one- quarter turn apart,
disconnect the driveshaft and re- index to align the marks as closely as possible. After any
corrections are made, recheck for vibration at the road test speed. If the vibration is gone,
reinstall the wheels and road test. If the vibration persists, proceed to Step 4.
4. Raise the vehicle on a hoist and remove the wheels. Rotate the driveshaft by turning the axle and measure the runout at the front, the center, and the rear of the driveshaft with the indicator.
If the runout exceeds 0.89 mm (0.035 inch) at the front or center, a new driveshaft must be
installed. If the front and center are within this limit, but the rear runout is not, mark the rear
runout high point and proceed to Step 5. If the runout is within the limits at all points, proceed to
Step 7.
5. NOTE: Check the U-joints during re- indexing. If a U-joint feels stiff or gritty, install new U- joints.
Scribe alignment marks on the driveshaft and the pinion flange. Disconnect the driveshaft,
rotate it one-half turn, and reconnect it. Circular pinion flanges can be turned in one- quarter
increments to fine tune the runout condition. Check the runout at the rear of the driveshaft. If it is
still over 0.89 mm (0.035 inch), mark the high point and proceed to Step 6. If the runout is no
longer excessive, check for vibration at the road test speed. If vibration is still present, re- index
the driveshaft slip yoke on the transmission output shaft one- half turn and road test the vehicle.
If the vibration persists, proceed to Step 7.
6. Excessive driveshaft runout may originate in the driveshaft itself or in the pinion flange. To determine which, compare the two high points marked in Steps 4 and 5. If the marks are close
together, within about 25 mm (1 inch), a new shaft must be installed and the vehicle road
tested. Klj . 12 ba
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If no improvement is noted, rotate the clamps in opposite directions, equal distances from the best
position determined in Step 8. Separate the clamp heads about 13 mm (1/2 inch) and recheck for
vibration at the road speed.
Repeat the process with increasing separation until the best combination is found or the vibration is
reduced to an acceptable level.
10. Install the wheels and road test (vibration noticeable on the hoist may not be evident during the road test). If the vibration is still not acceptable, install a new axle driveline vibration damper
first, if so equipped. If the vibration is still not acceptable, refer to Section 205 - 02A or
Section 205 - 02B for differential case and ring gear runout checks.
Driveshaft Vibrates 1. Road test the vehicle to determine the critical vibration points. Note the road speed, the engine RPM, and the shift lever positions at which the vibration occurs.
2. Stop the vehicle, place the transmission lever in neutral and run the engine through the critical speed ranges determined in Step 1.
3. If no vibration is felt, balance the driveshaft. Refer to Driveline Vibration in this section.
Traction- Lok® Differential Operation Check
A Traction-Lok® differential can be checked for correct operation without removing it from the rear axle
housing.
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 Klj . 14 ba
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off the floor.
With the engine off, raise only one rear wheel. Install the special tool on the wheel nuts.
Use a torque wrench with a capacity of at least 271 Nm (200 lb-
ft) to rotate the axle shaft. Be sure that
the transmission is in NEUTRAL, and that one rear wheel is on the floor while the other rear wheel is
raised off the floor. The breakaway torque required to start rotation must be at least 27 Nm (20 lb- ft).
The initial breakaway torque may be higher than the continuous turning torque.
The axle shaft must turn with even pressure throughout the check without slipping or binding. If the
torque reading is less than specified, check the differential case. Refer to Section 205 - 02A or
Section 205 - 02B .
Traction- Lok® Differential Check Road Test
1. Place one wheel on a dry surface and the other wheel on ice, mud or snow.
2. Gradually open the throttle to obtain maximum traction prior to break away. The ability to move the vehicle demonstrates correct operation of a Traction- Lok® rear axle assembly.
3. When starting with one wheel on an excessively slippery surface, a slight application of the parking brake may be necessary to help energize the Traction- Lok® feature of the differential.
Release the brake when traction is established. Use light throttle on starting to provide
maximum traction.
4. If, with unequal traction, both wheels slip, the limited slip rear axle has done all it can possibly do.
5. In extreme cases of differences in traction, the wheel with the least traction may spin after the Traction-Lok® has transferred as much torque as possible to the non- slipping wheel. Klj . 15 ba
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wheels.
z Consists of two single- cardan universal joints, a driveshaft slip yoke, a welded tube assembly
and a driveshaft centering socket yoke.
z The splined driveshaft slip yoke permits the driveshaft to move forward and rearward on the
transmission output shaft during drivetrain movement and during driveshaft removal and
installation. Klj . 2 ba
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4 4222 Differential bearing cup
5 4067 Differential bearing shim
6 4216 Rear axle differential gear case bolt
7 4204 Differential case
8 — Ring gear (part of 4209)
9 — Bearing cap (part of 4010)
10 4010 Rear axle housing
11 373098-
S Filler plug
12 4662 Collapsible spacer
13 4670 Rear axle drive pinion shaft oil slinger
14 4676 Rear axle drive pinion seal
15 4851 Pinion flange
16 389546-S100 Pinion nut
17 4621 Differential pinion bearing
18 2C026 Rear brake disc
19 — Axle shaft flange (part of 4234)
20 2C189 Rear brake anti-
lock sensor indicator 21 2552 Rear disc brake caliper
22 N601951-S2 Bolt
23 N804361-S100 Clip
24 — Bolt
25 2C190 Rear brake anti-
lock sensor 26 2C101 Left hand rear disc brake adapter
27 2C100 Right hand rear disc brake adapter
28 N8015163-S190 Caliper anchor bolt
29 2C028 Rear wheel brake disc shield
30 N602726-S2 Bolt (3 req'd)
31 4616 Differential drive pinion bearing cup
32 4628 Rear axle pinion bearing cup
33 4630 Differential pinion bearing
34 — Drive pinion gear
(part of 4209)
35 4663 Drive pinion bearing adjustment shim
36 — Bolt (part of 4010)
37 4241 Differential pinion shaft lock bolt
38 4211 Differential pinion shaft
39 4N237 U-
washer 40 383548 Bolt
41 — Rear axle identification tag
42 4033 Differential housing cover
43 4230 Differential pinion thrust washer
44 4215 Differential pinion gear Klj . 2 ba
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