Ford Falcon. Manual — part 494

501-25E-2

Body Repairs - Wind Noise

501-25E-2

DESCRIPTION AND OPERATION

The build-up and decay of turbulence and the

Wind Noise

associated pressure changes lead to creation of
sound waves. A similar effect can be observed at the

General

A-pillar on a vehicle. Here the area where eddies are

Wind noise can not be completely eliminated,

usually formed is directly above the side window. This

however the aim of vehicle development is to

makes it easy for the noise (roaring) to be passed to

significantly reduce wind noise levels and increase

the vehicle interior.

customer comfort is to reduce wind noise. The quieter

Eddy current zone

that noise producing components such as the engine,
drive train, tyres etc. become, the more the wind noise
at high speeds will be heard.
Apart from general wind rush, some noises may arise
which are typically heard as an irritating hissing or
whistling. The causes of these noises may be partly
caused by production or repair factors. They are
mostly caused by incorrectly mounted components,
which must be correctly installed in the correct
position.

Normal air flow noises

At high speed, as air flows past uniform flat surfaces
such as the roof, side windows, etc., turbulent air
layers form, in which air pressure variations occur.
Part of this pressure variation spreads in the form of

Item

Description

sound waves and is transferred to the vehicle interior

1

Air flow

by the side windows and seals. Here the noise is

2

Build up of eddies

particularly loud because of the closeness of the side
window to the driver or passenger. The noise

Eddy currents are also formed underneath the

experienced is mostly a low roaring, which becomes

vehicle, and so associated noise is also produced.

louder as speed increases.

When air flows past smaller components or through
smaller gaps (such as the radiator grill), the roaring

Noises caused partly by changes in the

noise can become a whistling, which may increase in

direction of air flow and by air flow

pitch and becomes louder as speed increases.

around separate components

Noise caused by vibrating seals

If air flows over an edge on a vehicle, the air flow

Seals which are not making firm contact in the window

cannot fully the contour of the surface, and it breaks

and door areas can also lead to vibrations caused by

up at the edge. Eddies are formed, which collapse

pressure variations on the outside of the vehicle which

again after a certain time or distance.

then means transfer of noise into the vehicle interior.

Change in the direction of air flow

The vibrating part of the seal operates here in the
same way as loudspeaker membrane. This type of
noise could be described as a "buzz" and sometimes
can originate around windscreen perimeters.

Item

Description

1

Eddy

2

Sound Wave

3

Flow

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501-25E-3

Body Repairs - Wind Noise

501-25E-3

DESCRIPTION AND OPERATION (Continued)

resonate. The note produced depends on the volume

Origin of vibrations (diagram)

of the cavity and the size of the opening. (For
example, making a note by blowing across the top of
a bottle).

Wind noise with the sun roof open

Problem:

When the sliding roof is open at about 60 km/h a
low frequency noise is produced (drumming).

Cause:

When the sliding roof is fully open, perceptible air
pressure variations occur inside the vehicle
because of the air current over the opening.

Corrective action:

Item

Description

At speeds above about 60km/h, close the sliding

1

Vibrating Seal

roof slightly until the drumming noise is no longer

2

Radiation into the Vehicle Interior

heard.

Wind noises from the door seals

Escaping noises

Because of the air currents passing by the sides

Small leaks in the vehicle interior sealing system allow

of the bodywork and over the roof, the pressure

small currents of air to enter. This leads to the

outside is slightly lower. Because of the heating

creation of "free stream noise" (a stream of air mixes

and ventilation system the pressure inside the

with still air and in doing so causes turbulence). The

vehicle is slightly higher. This pressure difference

loudness of free stream noise increases strongly with

causes, for example, the doors to lift away from

increasing escape speed and can be heard as a

the seals by several millimetres at high speeds. If

hissing noise (for example, letting the air out of a

there is also a side wind affecting the moving

tyre).

vehicle, this effect is increased.

Cavity noises

The resulting differences in gap are compensated
for by the use of flexible door seals (when the

If a bodywork cavity is open to the outside of the

door seals are intact).

vehicle, this can cause the air volume in the cavity to

Routes by which external sound is transferred to the inside of a vehicle

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501-25E-4

Body Repairs - Wind Noise

501-25E-4

DESCRIPTION AND OPERATION (Continued)

Item

Description

Item

Description

4

Sun roof seal

1

Interior ventilation

5

Primary and Secondary Door Seals

2

Windscreen sealing

6

Boot lid seal

3

Glass run w/strip

7

Interior ventilation

Wind noises

Type of wind noise

Where do they arise?

Normal

Normal air flow noises

Roof, side windows

Noises caused partly by changes

A-pillars, side mirrors, windscreen

in the direction of air flow and by

wipers

air flow around separate

components

Concern

Noises caused by vibrations seals

Door gaps too wide, door/window

(ie. "buzz"

seals not seated firmly

Air escape and air passage noises

Leaks in the bodywork sealing

system

Cavity noises

Unsealed bodywork cavities

Summary

The correct gap between the door and A-pillar or
door and roof

The creation and intensity of wind noise on a vehicle
depends on the fundamental shape and structure of
the different components.
There are two subjective evaluation and service
diagnosis methods in which sound levels can be
reduced and sound nature improved in a vehicle
interior:

Reduction in the intensity of the noise sources
Reduction of the noise transmission routes

In order to achieve a general improvement in the wind
noise situation in the vehicle, both factors must be
taken into account. The sealing systems of the doors,
windows and tailgate have a major influence on the
acoustic comfort in a vehicle.

Problem sources in practice

Adjustment of the tailgate

Diagnosis:

Seal on driver and passenger door

Wind noise coming from where the roof meets

Diagnosis:

the top edge of the tailgate

Wind noise from the door seal at the top of

Cause:

the door

Tailgate is set too high

Cause:

Corrective action:

The alignment of the door frame to the

Loosen the tailgate where it is attached at the

roof/bodyside is incorrect

hinges and move the tailgate further down.

Corrective action:

When doing so, pay attention to the gaps with

Re-align the door with the side window open

adjacent components.

Check the door seal to sealing surface
contact area. The width of the sealing area or
"footprint" should be at least 5mm.

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501-25E-5

Body Repairs - Wind Noise

501-25E-5

DESCRIPTION AND OPERATION (Continued)

Reset the lock if necessary.

The seal around the sun roof must touch it
evenly all round.

Tailgate too high

Correct installation of the sun roof

Sun roof adjustment

Adjustment of the right-hand windscreen

Diagnosis:

wiper arm

Wind noise from the sun roof

Diagnosis:

Cause:

Wind noise from the area of the right-hand

Sun roof incorrectly adjusted

windscreen wiper

Corrective action:

Cause:

Adjust the sun roof according to the following

Windscreen wiper arm is set too high

requirements:

Corrective action:

There must be an equal gap all round the sun

Remove the wiper arm from its shaft and

roof.

reposition it so that it lies within the black

The sun roof must be adjusted to suit the roof

ceramic band on the w/screen.

contour.
The front edge of the sun roof should close
flush with the top face of the roof itself, or
slightly lower.

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