2003 FORD MUSTANG tires

condition. It may not always be necessary to follow a pinpoint test to its conclusion. Carry out only the
steps necessary to correct the condition. Then, test the system for normal operation. Sometimes, it is
necessary to remove various vehicle components to gain access to the component requiring testing.
Reinstall all components after verifying system operation is normal.
PINPOINT TEST A: BRAKE VIBRATION/SHUDDER
Test Step Result / Action to Take
A1 ROAD TEST THE VEHICLE—
LIGHT BRAKING z
Check that the wheel and tires are correct for the vehicle.
Inspect the tires for abnormal wear patterns.
z Road test the vehicle. Warm the brakes by slowing the vehicle
a few times from 80– 32 km/h (50 to 20 mph) using light braking
applications. At highway speeds of 89–97 km/h (55- 60 mph),
apply the brake using a light pedal force.
z Is there a vibration/shudder felt in the steering wheel, seat
or brake pedal? Yes
GO to
A4 .
No
GO to A2 .
A2 ROAD TEST THE VEHICLE—
MODERATE TO HEAVY
BRAKING z
Road test the vehicle. At highway speeds of 89–97 km/h (55- 60
mph), apply the brake using a moderate to heavy pedal force.
z Is there a vibration/shudder? Yes
For vehicles with ABS,
GO to
A3 . For vehicles
with standard brakes,
GO to A4 .
No
Vehicle is OK. VERIFY
condition with customer.
TEST the vehicle for
normal operation. A3 NORMAL ACTUATION OF THE ABS SYSTEM DIAGNOSIS
z
During moderate to heavy braking, noise from the hydraulic
control unit (HCU) and pulsation in the brake pedal can be
observed. Pedal pulsation coupled with noise during heavy
braking or on loose gravel, bumps, wet or snowy surfaces is
acceptable and indicates correct functioning of the ABS
system. Pedal pulsation or steering wheel nibble, (frequency is
proportioned to the vehicle speed) indicates a concern with a
brake or suspension component.
z Is the vibration/shudder vehicle speed sensitive? Yes
GO to
A5 .
No
The brake system is
operating correctly. A4 APPLICATION OF THE PARKING BRAKE
z
NOTE: Begin at the front of the vehicle unless the vibration or
shudder has been isolated to the rear.
z This test is not applicable to vehicles with drum- in-hat type
parking brakes. For vehicles with drum- in-hat parking brakes,
proceed to the next test. For all other vehicles, apply the
parking brake to identify if the problem is in the front or rear
brake. At highway speeds of 89–97 km/h (55- 60 mph), lightly
apply the parking brake until the vehicle slows down. Release
the parking brake immediately after the test.
z Is there a vibration/shudder? Yes
GO to
A7 .
No
GO to A5 .
A5 CHECK THE FRONT WHEEL BEARINGS
z
Check the front wheel bearings. Refer to Wheel Bearing Check in this section.
z Are the wheel bearings OK? Yes
GO to
A6 . Klj . 48 ba
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Take
J1 ROAD TEST THE VEHICLE
z
NOTE: Wheel or tire vibrations felt in the steering wheel are most
likely related to the front wheel or tire. Vibration felt through the
seat are most likely related to the rear wheel or tire. This may not
always be true, but it can help to isolate the problem to the front
or rear of the vehicle.
z Test drive the vehicle at different speed ranges.
z During the road test, if the vibration can be eliminated by placing
the vehicle in neutral or is affected by the speed of the engine,
the cause is not the wheels or tires.
z Is there a vibration and noise? Yes
GO to
J2 .
No
The wheel and tires
are OK. CONDUCT a
diagnosis on other
suspect systems. J2 CHECK THE FRONT WHEEL BEARINGS
z
Check the front wheel bearings. Refer to Wheel Bearing Check in
this section.
z Are the wheel bearings OK? Yes
GO to
J3 .
No
INSPECT the wheel
bearings. ADJUST or
REPAIR as necessary.
TEST the system for
normal operation. J3 INSPECT THE TIRES
z
Check the tires for missing weights.
z Check the wheels for damage.
z Inspect the tire wear pattern. Refer to the Tire Wear Patterns
chart in this section.
z Do the tires have an abnormal wear pattern? Yes
CORRECT the
condition that caused
the abnormal wear.
INSTALL new tire(s).
TEST the system for
normal operation.
No
GO to
J4 .
J4 TIRE ROTATION
z
Spin the tires slowly and watch for signs of lateral runout.
z Spin the tires slowly and watch for signs of radial runout. Yes
GO to
J5 .
No
CHECK the wheel and
tire balance.
CORRECT as
necessary. TEST the
system for normal
operation. Klj . 56 ba
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z
Are there signs of visual runout? J5 RADIAL RUNOUT CHECK ON THE TIRE
z
Measure the radial runout of the wheel and tire assembly. A
typical specification for total radial runout is 0.045 inch.
z Is the radial runout within specifications? Yes
GO to
J8 .
No
GO to J6 .
J6 RADIAL RUNOUT CHECK ON THE WHEEL
z
Measure the radial runout of the wheel. A typical specification for
total radial runout is 0.045 inch.
z Is the radial runout within specifications? Yes
INSTALL a new tire.
TEST the system for
normal operation.
No
GO to
J7 .
J7 CHECK THE HUB/BRAKE DISC OR DRUM PILOT RUNOUT OR
BOLT CIRCLE RUNOUT z
Measure the pilot or bolt circle runout. A typical specification for
radial runout is:
zPilot runout— less than 0.15 mm (0.006 inch).
z Bolt circle runout— less than 0.38 mm (0.015 inch).
z Is the radial runout within specifications? Yes
INSTALL a new wheel.
TEST the system for
normal operation.
No
REPAIR or INSTALL
new components as
necessary. REFER to
Section 204
- 01 for the
front wheels or Section 204 - 02 for the rear
wheels. J8 LATERAL RUNOUT CHECK ON THE TIRE
z
Measure the lateral runout of the wheel and tire assembly. A
typical specification for total lateral runout is 1.14 mm (0.045
inch). Yes
Wheel and tires OK.
CONDUCT diagnosis
on other suspect
systems. Klj . 57 ba
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PINPOINT TEST K: HIGH SPEED SHAKE OR SHIMMY z
Is the lateral runout within specifications? No
GO to
J9 .
J9 LATERAL RUNOUT CHECK ON THE WHEEL
z
Measure the lateral runout of the wheel. A typical specification for
total radial runout is 1.14mm (0.045 inch.
z Is the lateral runout within specifications? Yes
INSTALL a new tire.
TEST the system for
normal operation.
No
GO to
J10 .
J10 CHECK THE FLANGE FACE LATERAL RUNOUT
z
Measure the flange face lateral runout. A typical specification for
lateral runout is:
zHub/brake disc— less than 0.13 mm (0.005 inch).
z Axle shaft— less than 0.25 mm (0.010 inch).
z Is the lateral runout within specifications? Yes
INSTALL a new wheel.
TEST the system for
normal operation.
No
REPAIR or INSTALL
new components as
necessary. REFER to
Section 204
- 01 for the
front wheels or Section 204 - 02 for the rear
wheels. Test Step Result / Action to Take
K1 CHECK FOR FRONT WHEEL BEARING ROUGHNESS
z
Chock the rear wheels.
z Raise and support the front end of the vehicle so that the front
wheel and tire assemblies can spin.
z Spin the front tires by hand. Refer to Wheel Bearing Check in
this section.
z Do the wheel bearings feel rough? Yes
INSPECT the wheel
bearings. REPAIR as
necessary. TEST the
system for normal
operation.
No
GO to
K2 .
K2 CHECK THE END PLAY OF THE FRONT WHEEL BEARINGS
z
Check the end play of the front wheel bearings. Refer to
Section 204 - 01 .
z Is the end play OK? Yes
GO to
K3 .
No
ADJUST or REPAIR as
necessary. TEST the
system for normal Klj . 58 ba
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operation.
K3 MEASURE THE LATERAL RUNOUT AND THE RADIAL
RUNOUT OF THE FRONT WHEELS ON THE VEHICLE z
Measure the lateral runout and the radial runout of the front
wheels on the vehicle. Refer to Go To Pinpoint Test J .
z Are the measurements within specifications? Yes
GO to
K4 .
No
INSTALL new wheels as
necessary and BALANCE
the assembly. TEST the
system for normal
operation. K4 MEASURE THE LATERAL RUNOUT OF THE FRONT TIRES
ON THE VEHICLE z
Measure the lateral runout of the front tires on the vehicle. Go To Pinpoint Test J .
z Is the runout within specifications? Yes
GO to
K5 .
No
INSTALL new tires as
necessary and BALANCE
the assembly. TEST the
system for normal
operation. K5 MEASURE THE RADIAL RUNOUT OF THE FRONT TIRES
ON THE VEHICLE z
Measure the radial runout of the front tires on the vehicle. Go To Pinpoint Test J .
z Is the runout within specifications? Yes
BALANCE the front wheel
and tire assemblies. If any
tire cannot be balanced,
INSTALL a new tire.
TEST the system for
normal operation.
No
GO to
K6 .
K6 MATCH MOUNT THE TIRE AND WHEEL ASSEMBLY
z
Mark the high runout location on the tire and also on the
wheel. Break the assembly down and rotate the tire 180
degrees (halfway around) on the wheel. Inflate the tire and
measure the radial runout.
z Is the runout within specifications? Yes
BALANCE the assembly.
TEST the system for
normal operation.
No
If the high spot is not
within 101.6 mm (4
inches) of the first high
spot on the tire, GO to
K7
.
K7 MEASURE THE WHEEL FLANGE RUNOUT
z
Dismount the tire and mount the wheel on a wheel balancer.
Measure the runout on both wheel flanges. Go To Pinpoint Test J . Yes
LOCATE and MARK the
low spot on the wheel.
INSTALL the tire,
matching the high spot on
the tire with the low spot
on the wheel. BALANCE
the assembly. TEST the
system for normal
operation. If the condition Klj . 59 ba
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Wheel and tire NVH concerns are directly related to vehicle speed and are not generally affected by
acceleration, coasting or decelerating. Also, out-of-
balance wheel and tires can vibrate at more than
one speed. A vibration that is affected by the engine rpm, or is eliminated by placing the transmission
in NEUTRAL is not related to the tire and wheel. As a general rule, tire and wheel vibrations felt in the
steering wheel are related to the front tire and wheel assemblies. Vibrations felt in the seat or floor are
related to the rear tire and wheel assemblies. This can initially isolate a concern to the front or rear.
Careful attention must be paid to the tire and wheels. There are several symptoms that can be caused
by damaged or worn tire and wheels. Carry out a careful visual inspection of the tires and wheel
assemblies. Spin the tires slowly and watch for signs of lateral or radial runout. Refer to the tire wear
chart to determine the tire wear conditions and actions. Klj . 68 ba
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For a vibration concern, use the vehicle speed to determine tire/wheel frequency and rpm. Calculate
tire and wheel rpm and frequency by carrying out and following:
zMeasure the diameter of the tire.
z Record the speed at which the vibration occurs.
z Obtain the corresponding tire and wheel rpm and frequency from the Tire Speed and Frequency
Chart.
„If the vehicle speed is not listed, divide the vehicle speed at which the vibration occurs by
16 km/h (10 mph). Multiply that number by 16 km/h (10 mph) tire rpm listed for that tire
diameter in the chart. Then divide that number by 60. For example: a 40 mph vibration
with 835 mm (33 in) tires. 40 ÷ 10 = 4. Multiply 4 by 105 = 420 rpm. Divide 420 rpm by 60
seconds = 7 Hz at 40 mph.
Tire Speed and Frequency Chart Tire
Diameter Tire RPM/Hz Tire RPM/Hz Tire RPM/Hz Tire RPM/Hz
mm (inch) @ 16 km/h (10
mph) @ 80 km/h (50
mph) @ 97 km/h (60
mph) @ 113 km/h (70
mph) 483 (19) 182 910/15 1092/18 1274/21
508 (20) 173 865/14 1038/17 1211/20
533 (21) 165 825/14 990/16 1155/19
560 (22) 158 790/13 948/16 1106/18
585 (23) 151 755/13 906/15 1057/18
610 (24) 145 725/12 870/14 1015/17
635 (25) 139 695/12 834/14 973/16
660 (26) 134 670/11 804/13 938/16
685 (27) 129 645/11 774/13 903/15
710 (28) 124 620/10 744/12 868/14
735 (29) 119 595/10 714/12 833/14
760 (30) 115 575/10 690/11 805/13
785 (31) 111 555/9 666/11 777/13
810 (32) 108 540/9 648/11 756/13
835 (33) 105 525/9 630/10 735/12
864 (34) 102 510/8 612/10 714/12 Klj . 69 ba
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GENERAL PROCEDURES
Wheel Bearing Check
1. WARNING: The electrical power to the air suspension system must be shut off prior
to hoisting, jacking or towing an air suspension vehicle. This can be accomplished by
turning off the air suspension switch. Failure to do so can result in unexpected inflation
or deflation of the air springs, which can result in shifting of the vehicle during these
operations.
Raise the vehicle until the front tires are off the floor.
zMake sure the wheels are in a straight forward position.
2. NOTE: Make sure the wheel rotates freely and that the brake pads are retraced sufficiently to
allow free movement of the tire and wheel assembly.
Spin the tire by hand to check the wheel bearings for roughness.
3. Grip each front tire at the top and bottom and move the wheel inward and outward while lifting the weight of the tire off the front wheel bearing.
4. If the tire and wheel (hub) is loose on the spindle, does not rotate freely, or has a rough feeling when spun, carry out one of the following:
1. On vehicles with inner and outer bearings, inspect the bearings and cups for wear or damage. Adjust or install new bearings and cups as necessary.
2. On vehicles with one sealed bearing, install a new wheel hub.
SECTION 100-
04: Noise, Vibration and Harshness 2003 Mustang Workshop Manual Klj . 1 ba
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