FORD MUSTANG 2003 Workshop Manual

4. While the noise is occurring, either place an EngineEAR probe near the IAC valve and the inlet
tube, or create a 6.35 mm (0.25 in)- 12.7 mm (0.50 in) air gap between the inlet tube and the
clean air tube. If the IAC valve is making the noise, install a new IAC valve.
5. Test the vehicle for normal operation.
Steering Gear Grunt/Shudder Test
1. Start and run the vehicle to operating temperature.
2. Set engine idle speed to 1200 rpm.
3. CAUTION: Do not hold the steering wheel against the stops for more than three to
five seconds at a time. Damage to the power steering pump will occur.
Rotate the steering wheel to the RH stop, then turn the steering wheel 90° back from that
position. Turn the steering wheel slowly in a 15° to 30° arc.
4. Turn the steering wheel another 90°. Turn the steering wheel slowly in a 15° to 30° arc.
5. Repeat the test with power steering fluid at different temperatures.
6. If a light grunt is heard or a low (50- 200 Hz) shudder is present, this is a normal steering system
condition.
7. If a loud grunt is heard, or a strong shudder is felt, fill and purge the power steering system.
Checking Tooth Contact Pattern and Condition of the Ring and Pinion
There are two basic types of conditions that will produce ring and pinion noise. The first type is a howl
or chuckle produced by broken, cracked, chipped, scored or forcibly damaged gear teeth and is
usually quite audible over the entire speed range. The second type of ring and pinion noise pertains to
the mesh pattern of the gear pattern. This gear noise can be recognized as it produces a cycling pitch
or whine. Ring and pinion noise tends to peak in a narrow speed range or ranges, and will tend to
remain constant in pitch.
1. Raise and support the vehicle. For additional information, refer to Section 100 - 02 .
2. Drain the axle lubricant. Refer to Section 205 - 02A for Ford 7.5 rear axles or
Section 205 - 02B for
Ford 8.8 integral axles.
3. Remove the carrier assembly or the axle housing cover depending on the axle type. Refer to Section 205 - 02A for Ford 7.5 rear axles or
Section 205 - 02B for Ford 8.8 integral axles.
4. Inspect the gear set for scoring or damage. Klj . 64 ba
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5. In the following steps, the movement of the contact pattern along the length is indicated as
toward the" heel" or "toe" of the differential ring gear.
6. Apply a marking compound to a third of the gear teeth on the differential ring gear. Rotate the differential ring gear several complete turns in both directions until a good, clear tooth pattern is
obtained. Inspect the contact patterns on the ring gear teeth.
7. A good contact pattern should be centered on the tooth. It can also be slightly toward the toe. There should always be some clearance between the contact pattern and the top of the tooth.
z Tooth contact pattern shown on the drive side of the gear teeth. 8. A high, thick contact pattern that is worn more toward the toe. Item Description
1 Heel
2 Toe Klj . 65 ba
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z
Tooth contact pattern shown on the drive side of the gear teeth.
z The high contact pattern indicates that the drive pinion is not installed deep enough into the
carrier.
z The differential ring gear backlash is correct, a thinner drive pinion shim is needed. A decrease
will move the drive pinion toward the differential ring gear.
9. A high, thin contact pattern that is worn toward the toe. z Tooth contact pattern shown on the drive side of the gear teeth.
z The drive pinion depth is correct. Increase the differential ring gear backlash.
10. A contact pattern that is worn in the center of the differential ring gear tooth toward the heel. z Tooth contact pattern shown on the drive side of the gear teeth.
z The low contact pattern indicates that the drive pinion is installed too deep into the carrier.
z The differential ring gear backlash is correct. A thicker drive pinion shim is needed.
11. A contact pattern that is worn at the top of the differential ring gear tooth toward the heel. Klj . 66 ba
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z
Tooth contact pattern shown on the drive side of the gear teeth.
z The pinion gear depth is correct. Decrease the differential ring gear backlash.
Tire Wear Patterns and frequency calculations Tire Wear Chart Klj . 67 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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Klj . 70 ba
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GENERAL PROCEDURES
Brake Disc Machining
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.
CAUTION: Do not install brake discs that are less than the minimum thickness specified.
Do not machine a brake disc below the minimum thickness specification.
1. Check wheel bearing end- play and correct as necessary.
2. NOTE: Begin at the front of the vehicle unless the vibration has been isolated to the rear.
Remove the tire and wheel assembly.
3. Remove the brake caliper and the brake caliper anchor plate. Refer to the appropriate section in Group 206 for the procedure.
4. Inspect the brake linings. Install new brake linings if below specification. For additional information, refer to the appropriate brake section.
5. Measure and record the brake disc thickness. Install a new brake disc if the thickness after machining will be at or below specification. The specification is molded into the brake disc.
zDo not machine a new brake disc.
SECTION 100-
04: Noise, Vibration and Harshness 2003 Mustang Workshop Manual Special Tool(s)
Gauge, Clutch Housing
308-
021 (T75L-4201- A) Dial Indicator Gauge with
Holding Fixture
100-
002 (TOOL- 4201-C) or
equivalent
Material Item Specification
Metal Surface Cleaner
F4AZ-
19A536- RA or equivalent WSE-
M5B392-
A High Temperature Nickel Anti-
Seize Lubricant
F6AZ-
9L494- AA or equivalent ESE-
M12A4-A Klj . 1 ba
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6. For vehicles with a two-
piece hub and brake disc assembly:
z Match-mark before disassembly.
z Remove the brake disc.
z Clean the hub and brake disc mounting surfaces with metal surface cleaner.
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.
7. 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 an on- car brake lathe, machine the brake discs. Follow the manufacturer's instructions.
After machining, make sure the brake disc still meets the thickness specification.
8. Using the special tools, verify that the brake disc lateral runout is now within specification. For additional information, refer to Section 206 - 00 .
9. Remove the special tool hub adapter.
10. Remove any remaining metal chips from the machining operation.
11. For vehicles with a two- piece hub and 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 a liberal amount of lubricant to the hub flange, pilot area and to the brake disc- to-
hub mounting surface.
z Using the match marks, mount the brake disc on the hub.
12. Install the brake caliper anchor plate and the brake caliper.
13. Install the tire and wheel assembly.
14. Test the system for normal operation. Klj . 2 ba
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