DIAGNOSIS AND TESTING
E1049 EN 06/2001 2002 Bantam
Suspension System
CAUTION: Make sure the tyres are
inflated to their correct pressures before
and after this check is completed.
Vibrations, roughness, tramp, shimmy and thump
may be caused by excessive tyre or wheel run
out, worn or cupped tyres, or wheel and tyre
imbalance.
These conditions may also be caused by rough
or undulating road surfaces. Driving the vehicle
on different types of road surfaces will indicate if
the road surfaces are actually causing the
conditions.
Do not immediately suspect the tyres when
attempting to diagnose a vibration concern. Other
sources of vibration include:
• Loose or worn front wheel bearing.
• Loose or worn suspension or steering
components.
• Excessive front brake disc run out.
• Loose engine or transaxle supports.
• Engine driven accessories.
This section covers those vibrations related to the
suspension, tyres and wheels.
A thumping noise usually means that the tyre has
flat or soft spots making a noise as they slap the
roadways. Tyre whine can be distinguished from
axle noise because axle noise diminishes or
changes according to load or
with a road test. REFER to Section 100-04. The
speed. Tyre noise
remains the same over a range of speeds.
To verify that tyre noise is not associated with
shake or vibration, over inflate the tyres one at a
time and check for a change in the sound. The
pitch or whine will change as the increased
pressure changes the tyre frequency.
Check for other types of vibration.
REFER to Section 100-04.
Inspection and Verification
A vibration diagnostic procedure always begins
road test and customer interview (if available) will
provide much of the information needed to find
the source of a vibration.
During the road test, drive the vehicle on a road
that is smooth and free of undulations. If a
vibration is apparent, note and record the
following:
• The speed at which the vibration occurs.
• What type of vibration occurs in each speed
range – mechanical or audible.
• How the vibration is affected by changes in
engine torque, vehicle speed and engine
speed.
• Type of vibration sensitivity – torque
sensitive, vehicle speed sensitive, or engine
speed sensitive.
If the road test indicates the vibration is related to
the tyres or wheels, use the Tyre Wear Condition
Chart to help pinpoint the cause of the concern. If
the road test indicates that there is tyre whine but
no shake or vibration, the noise originates with
the contact between the tyre and the road
surface.
Use the following explanation of terms to help
isolate the source of the vibration:
Torque Sensitive
This means that the condition can be improved or
worsened by accelerating, decelerating, coasting
or maintaining a steady vehicle speed.
Vehicle Speed Sensitive
This means that the vibration always occurs at
the same vehicle speed and is not affected by the
application of engine torque, engine speed, or
transaxle gear.
Engine Speed Sensitive
This means that the vibration occurs at varying
vehicle speeds when a different transaxle gear is
selected and the engine speed is constant.
Increasing or decreasing engine speed with the
transaxle in NEUTRAL or by stall testing with the
transaxle in gear can sometimes isolate it. If the
condition is engine speed sensitive, the condition
is not related to tyres.
Front End
NOTE: Do not check or carry out a front
suspension alignment without first making the
following inspection for front-end damage or
wear.
1. Check for specified air pressure in all four
tyres.
204-00-2 Suspension — General Information 204-00-2
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