2003 FORD MUSTANG test G

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.
SECTION 204-
04: Wheels and Tires 2003 Mustang Workshop Manual Klj . 1 ba
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DIAGNOSIS AND TESTING
Driveline System
SECTION 205-
00: Driveline System — General Information 2003 Mustang Workshop Manual Special Tool(s)
Clamp Plate
205-
320 (T92L-4851- C) Clutch Housing Alignment
Adapter
308-
021 (T75L-4201- A) Companion Flange Holding
Tool
205-
126 (T78P-4851- A) Companion Flange Runout
Gauge
205-
319 (T92L-4851- B) Dial Indicator with Bracketry
100-
002 (TOOL- 4201-C) or
equivalent Dial Indicator/Magnetic Base
100-
D002 (D78P-4201- B) or
equivalent Vibration Analyzer
100-
F027 (014- 00344) Traction-Lok® Torque Tool
205- 022 (T66L-4204- A) Klj . 1 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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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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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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