Aston Martin V8 Vantage Workshop Manual page 173

Road Wheels and Tyres (04.04)
Suspension (04.00)
Road Test
A tyre vibration diagnostic procedure always begins with a road test. The 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 vibration is apparent, note and
record the following:
• The speed at which the vibration occurs
• What type of vibration occurs in each speed range
• How the vibration is affected by changes in the following types of vibration-sensitivity:
Torque Sensitive - This means that the condition may be improved or made worse by accelerating, decelerating,
coasting, maintaining a steady vehicle speed or applying engine torque.
Vehicle Speed Sensitive - This means that the vibration always occurs at the same vehicle speed and is not affected by
engine torque, engine speed or the transmission gear selected.
Engine Speed Sensitive - This means that the vibration occurs at varying vehicle speeds when a different transmission
gear is selected. It may sometimes be isolated by increasing or decreasing engine speed with the transmission in NEUTRAL
or by stall testing with the transmission in gear. If the condition is engine speed sensitive, the cause is probably not related
to the tyres.
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.
A thumping noise usually means that the tyre has a flat or soft spot making a noise as they slap the roadway. Tyre whine
may be distinguished from axle noise. Tyre whine remains the same over a range of speeds.
Symptoms
Symptom
Tyres show excess wear on
edge of treads
Tyres show excess wear on
edge of treads (having the
correct tyre pressures)
Tyres show excess wear in
center of tread
Other excessive tyre wear
problems
Wheel mounting is difficult
Wobble or shimmy affecting
wheel runout
Excessive vibration, rough
steering or severe tyre wear
4-5-4
Possible Source(s):
Tyres under-inflated
Vehicle overloaded
Incorrect toe setting
Tyres over-inflated
Incorrect tyre pressure
Incorrect tyre and wheel usage
Geometry out of alignment
Loose, worn or damaged suspension
components
Wheel and tyre assembly out of
balance
Excessive lateral or radial runout of
wheel or tyre
Incorrect application or mismatched
parts, including wheel studs and wheel
nuts. Corroded, worn or damaged parts
Damaged wheel (eventually damaging
wheel bearings and causing uneven
tyre wear)
Loose or incorrect attaching parts
Workshop Manual
Action(s)
Correct pressure to specification.
Correct as required.
Set to specification.
Correct pressure to specification.
Correct pressure to specification.
Install correct tyre and wheel combination.
Check and adjust.
Inspect, repair or install new suspension
components as necessary.
Balance wheel and tyre assembly.
Check, repair or install a new wheel or tyre as
necessary.
Clean or install new parts.
Inspect wheel rims for damage and runout.
Install a new wheel rim as necessary.
Tighten or install new parts.
October 2005