2003 FORD MUSTANG Workshop Manual

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FORD MUSTANG 2003 Workshop Manual DESCRIPTION AND OPERATION
Noise, Vibration and Harshness (NVH)
Noise is any undesirable sound, usually unpleasant in nature. Vibration is any motion, shaking or
trembling, that can be felt or seen

DESCRIPTION AND OPERATION
Noise, Vibration and Harshness (NVH)
Noise is any undesirable sound, usually unpleasant in nature. Vibration is any motion, shaking or
trembling, that can be felt or seen when an object moves back and forth or up and down. Harshness is
a ride quality issue where the vehicle's response to the road transmits sharply to the customer.
Harshness normally describes a firmer than usual response from the suspension system. Noise,
vibration and harshness (NVH) is a term used to describe these conditions, which result in varying
degrees of dissatisfaction. Although, a certain level of NVH caused by road and environmental
conditions is normal. This section is designed to aid in the diagnosis, testing and repair of NVH
concerns.
Acceptable Noise, Vibration and Harshness
All internal combustion engines and drivelines produce some noise and vibration; operating in a real
world environment adds noise that is not subject to control. Vibration isolators, mufflers and dampers
reduce these to acceptable levels. A driver who is unfamiliar with a vehicle can think that some sounds
are abnormal when actually the sounds are normal for the vehicle type. For example, Traction-
Lok®
differentials produce a slight noise on slow turns after extended highway driving. This is acceptable
and has no detrimental effect on the locking axle function. As a technician, it is very important to be
familiar with vehicle features and know how they relate to NVH concerns and their diagnosis. For
example, if the vehicle has automatic overdrive, it is important to test drive the vehicle both in and out
of overdrive mode.
Diagnostic Theory
The shortest route to an accurate diagnosis results from:
zsystem knowledge, including comparison with a known good system.
z system history, including repair history and usage patterns.
z condition history, especially any relationship to repairs or sudden change.
z knowledge of possible sources.
z using a systematic diagnostic method that divides the system into related areas.
The diagnosis and correction of noise, vibration and harshness concerns requires:
za road or system test to determine the exact nature of the concern.
z an analysis of the possible causes.
z testing to verify the cause.
z repairing any concerns found.
z a road test or system test to make sure the concern has been corrected or brought back to
within an acceptable range.
Glossary of Terms SECTION 100-
04: Noise, Vibration and Harshness 2003 Mustang Workshop Manual Klj . 1 ba
152003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

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FORD MUSTANG 2003 Workshop Manual Acceleration-
Light
An increase in speed at less than half throttle.
Acceleration- Medium
An increase in speed at half to nearly full throttle, such as 0- 97 km/h (0-60 mph) in approximately 30
se

Page 35 of 4378

FORD MUSTANG 2003 Workshop Manual The angle of the wheel in relation to the true vertical as measured looking from the front of the vehicle.
Camber is positive when the wheel angle is offset so that the top of the wheel is positioned

Page 36 of 4378

FORD MUSTANG 2003 Workshop Manual Clonk
A hydraulic knocking sound. Sound occurs with air pockets in a hydraulic system. Also described as
hammering.
Clunk/Driveline Clunk
A heavy or dull, short-
duration, low-frequency sound. Occ

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FORD MUSTANG 2003 Workshop Manual starting point.
Decibel
A unit of measurement, referring to sound pressure level, abbreviated dB.
Drive Engine Run-
Up (DERU) Test
The operation of the engine through the normal rpm range with the

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FORD MUSTANG 2003 Workshop Manual The equal distribution of weight on each side of the centerline, so that when the wheel and tire
assembly spins, there is no tendency for the assembly to move from side-
to-side (wobble).
Dynamicall

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FORD MUSTANG 2003 Workshop Manual A mid-
range frequency (200- 800 Hz) noise between drumming and whine. Also described as a hum.
Hum
Mid- frequency (200- 800 Hz) steady sound, like a small fan motor. Also described as a howl.
Hz

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FORD MUSTANG 2003 Workshop Manual Pinion Shaft
The input shaft in a driving axle that is usually a part of the smaller driving or input hypoid gear of a
ring and pinion gearset.
Pitch
The physical quality of sound that relates to

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