Ford Falcon. Manual — part 495

501-25E-6

Body Repairs - Wind Noise

501-25E-6

DESCRIPTION AND OPERATION (Continued)

as when the wind noise was produced

Adjustment of the wiper arm

earlier.
If this road test does not show that the
work has been successful, additional
techniques such as powder testing,
stethoscope testing or ultrasonic detection
must be employed.

Workshop diagnosis

Before repair work is carried out, a visual check of the
vehicle must be performed, paying special attention to
the fit of the doors. When the doors are adjusted to fit
exactly, development of wind noise can often be
eliminated at high speeds (lifting of doors off the
seals).

Stethoscope testing

Item

Description

The stethoscope is a simple and appropriate tool

1

Too high (above black ceramic bend)

for finding bodywork air leaks. If the blower is

2

Correct (within black ceramic bend)

turned on at the highest speed and all the doors,
windows and other openings are closed, the air

Sequence for performing a wind noise

pressure inside the vehicle can be made higher

diagnosis

than that outside. The outside of the vehicle is
then checked for streams of escaping air.

1. Customer

concern

What is the customer concern and what

Powder test

details can they supply about the wind noise?

By coating the contact surface of the door seal

2. Under which conditions does the wind noise

with white powder (eg. chalk), door seals that do

appear?

not make close contact can be found. To do this,

1. Sequence A: A diagnosis is possible based

the door is carefully closed and re-opened. In this

on the details supplied by the customer.

way, the sealing surfaces which do not touch will

Carry out corrective measures to remedy

be visible.

the wind noise.

Ultrasonic detector

Road test the vehicle to check that the
concern is resolved. The vehicle must be

It is also possible to detect leaks using an

driven in the exactly same way as when

ultrasonic detector and a tone generator. To do

the wind noise was produced with the

this, the ultrasonic tone generator is put inside the

customer.

vehicle and the outside of the vehicle is tested

If the corrective measures based on the

using the detector tuned to the generator. The

information supplied by the customer

detector will quite easily show any leaks present.

were not successful, further testing must

Road tests

be carried out in the workshop (see
sequence B).

The causes and origins of wind noises can often

2. Sequence B: A diagnosis based on details

be located by a road test. Attention should be

supplied by the customer is not possible

paid to the following points:

Test for faults in the workshop, referring

Choose a dry, flat and straight road with as

to any TSB (Technical Service Bulletin)

little traffic as possible.

which may be relevant.

Make sure that the tyres are at the correct

Visually check external seals, check gaps.

pressure, to avoid tyre noise.

Visual check: Have any components been

Vehicle speed should be the max legal/safe

fitted to the vehicle after manufacture or

speed (eg. 100km/h)

has the vehicle been repaired after an
accident?

Road surface should be smooth

Perform a diagnosis based on the road

Wind speed should be minimal

test.

Testing should be carried out in N,E,S,W

Carry out corrective measures based on

directions if possible

the diagnosis.
Perform another road test. The vehicle

A separate rear seat auditor is required for

must be driven in the exactly same way

wind noise in the rear of the vehicle

G27425 en

501-25E-7

Body Repairs - Wind Noise

501-25E-7

DESCRIPTION AND OPERATION (Continued)

All windows should be checked to ensure
fitment and condition is correct
The A/C blower fan should be OFF
A standard medical stethoscope with the
amplifier and removed is a usefull aspiration
leak diagnosis tool (source from medical
suppliers or chemist)
Powered chalk can be used to idendify air
leak paths
If a suspect leak/source of wind noise has
been idendified the vehicle should be stopped
on the side of the road and cloth tape or
similiar used to cover the suspected
leak.Continue test and confirm leak ha sbeen
eliminated/reduced.

G27425 en

501-25G-1

Body Repairs - Noise, Vibration and Harshness

501-25G-1

SECTION : 501-25G Body Repairs - Noise,

Vibration and Harshness

VEHICLE APPLICATION : 2002.50 BA Falcon
CONTENTS

PAGE

DESCRIPTION AND OPERATION

Noise, Vibration and Harshness . . . . . . . . . . . . . . . . . . . . . . ..501-25G-2

Introduction

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501-25G-2

What is understood by NVH in vehicle technology . . . . . . . . . . . . . . ...501-25G-2

Types of noise in NVH technology . . . . . . . . . . . . . . . . . . . . . 501-25G-2

Noise transmission through air . . . . . . . . . . . . . . . . . . . . . . ..501-25G-2

Sound transmission through a body . . . . . . . . . . . . . . . . . . . . .501-25G-2

Combination of transmission through air and bodies . . . . . . . . . . . . . . 501-25G-3

Vibration

technology

. . . . . . . . . . . . . . . . . . . . . . . . . . ..501-25G-3

Noise and oscillation behaviour in a vehicle . . . . . . . . . . . . . . . . . .501-25G-6

Noise and oscillation behaviour of intake and exhaust systems . . . . . . . . . ...501-25G-6

Bodywork

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...501-25G-8

01/2003 2002.50 BA Falcon

501-25G-2

Body Repairs - Noise, Vibration and Harshness

501-25G-2

DESCRIPTION AND OPERATION

Where the different notes come from in a

Noise, Vibration and Harshness

vehicle:

Introduction

Low notes are mostly produced by the engine.

This chapter gives an overview of how noise, vibration

Low notes are also caused by the road surface,

and harshness (NVH) can be produced in a vehicle,

especially if the surface is rough. This is a form of

and which corrective measures are possible.

droning which can be felt by the vehicle

occupants as vibration or roughness.

What is understood by NVH in vehicle

High notes however, which are experienced as

technology

howling or whistling noises are often air currents

N = Noise - Sound, can be heard

(wind noise) or come from attached components

such as the generator, power steering pump or

V = Vibration - Oscillation, can be felt

drivebelt.

H = Harshness - Roughness, can be heard and felt

There are also clattering noises which can occur

Types of noise in NVH technology

when driving over an uneven road. These jerking

noises are produced by, for example, the shock

Noises in a vehicle are classified by their notes:

absorbers, chassis components or loose articles

Low notes - growling, droning

inside the vehicle.

Mid-pitch notes - buzzing, whirring

Noise transmission through air

High notes - howling, whistling, squeaking
Loud howling and whistling is painful to the

Spreading of sound waves in the air

ears.

Sound transmission through a body

Item

Description

1

Sound source e.g. Engine

Sound is passed through liquids or solids e.g. through

the car bodywork.

2

Sound wave

3

Amplitude

The sound is spread by longitudinal waves in the

form of pressure changes in the air.

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01/2003 2002.50 BA Falcon