CS35 2013.04
1.1.5-9 1.1.5-9Noise, Vibration and Harshness
Road T
e
st Quick Inspect
s
1.
2
4
~ 80 km / h:
W
i
th light acceleratio
n
, a moa
n
ing no
ise
is
h
eard and
possibly a vibration felt in the
front
floor p
ane
l. It is usually worse at a
p
a
rticu
l
ar
e
ngine
spe
ed and
at a p
a
rticular thro
ttle set-
ting
during
acceleration at
that
spe
ed.
It may
a
l
so
produce a
moan
ing sound
, depe
nding
on
what component is causing it. Refer to Tip-in
Moan in the
driveline noise
and vibration
sy
mptom c
h
art.
2.
Acceleratio
n
/Dece
l
eration:
W
i
th slow acceleratio
n
and d
e
celeration, a
shake is
sometimes no
tice
d in the
steering
wheel/column, seats, front floor panel, front
door trim panel or front end sheet metal. It is
a low frequency vibration (around 9-15 cycles
p
e
r se
cond
). It may or may
not b
e
in
creased
b
y
applying
th
e b
r
akes light
ly
.
Re
fer t
o
Id
le
boom/shake/vibration in the driveline noise
and vibration symptom chart.
3.
High S
peed:
A vibration is felt in the front floor panel or
seat
s wit
h
no visible shake, but with an
a
cco
mp
anying sound
o
r rumble, buzz, hu
m,
drone or booming noise. Coast with the clutch
p
edal dep
ressed (man
ual transmission) or
shift control selector lever in "N" (NEUTRAL)
(automatic transmission) and engine idling. If
vibra
t
ion is still eviden
t, it ma
y be rela
ted to
wheels, tires, front brake discs, wheel hubs or
fro
n
t
whe
e
l bearings.
Refer to shake and
vibra
t
ion
wh
ile
driving
in
the dr
iveline
noise
and vibration symptom chart.
4. Engine speed sensitivity:
A vibration is felt whenever the engine
reaches a particular rpm. It will disappear in
neutral coasts. The vibration can be dupli-
cated by operat
ing the en
gine
at
th
e problem
rpm while the vehicle is stationary. It can be
caused b
y
a
n
y
component, fro
m
the a
c
ces-
sory drive belt to the clutch or torque con-
verter which turns at engine speed when the
vehicle is stopped. Refer to shake and vibra-
tion while driving in the driveline noise and
vibration symptom chart.
5. Noise and vibration while turning (clicking,
popping or grinding noises) may be due to the
following:
• Worn, damaged or incorrectly installed
front wheel bearing.
• Damaged powertrain/drivetrain mounts.
Road Conditions
An experienced technician will always establish a
route that will be used for all NVH diagnosis road
test
s. The road selected sho
u
ld be reasonab
ly
smooth, level and free of undulations (unless a
particular condition needs to be identified). A
smooth asphalt road that allows driving over a
ran
ge of
spe
eds
is best. Gravel or
bump
y
roa
d
s
are
unsuit
able b
e
cau
s
e
of the
add
itio
nal
road
no
ise
produ
ced.
Once th
e rout
e is est
a
b
lished
an
d co
nsisten
t
ly
use
d
, the
road
noise varia
b
le
is
eliminated from the test results.
CAUTION: Some concerns may be appar-
ent only on smooth asphalt roads.
If
a cu
stomer complains of
a noise o
r
vibratio
n on
a p
a
rticular road and only
o
n
a p
a
rticular road, the
source of the concern may be the road surface. If
po
ssible
,
try
to test the
vehicle
on th
e sa
me type
of road.
Vehicle Preparation
Carry out a tho
r
ough visu
al in
spection
of the vehi-
cle before carrying out the road test. Note any-
thing
unusual.
Do no
t rep
a
ir or
adju
s
t a
n
y
condition until the road test is carried out, unless
the vehicle is inoperative or the condition could
po
se a
haza
r
d to th
e technician.
After verifying that the condition has been cor-
rected,
make sure all compo
nent
s re
moved ha
ve
been installed.
To Next Page
Loading...
