Repair Instructions; General Service Precautions; Correcting Tire And Wheel Vibration - GMC Chevrolet Camaro 1998 Service Manual

0-62 Vibration Diagnosis and Correction
Repair Instructions
General Service Precautions
Caution: One or more of the following guidelines
may apply when performing spetific,required tests
in the work stall: ·
1. When a test requires spinning the drive
wheels with the vehicle jacked up:
• On vehicles equipped with a limited-slip
differential, do not attempt to spin one drive
wheel with the other wheel on the ground.
The vehicle may drive through this
wheel and cause the vehicle to move
unexpectedly, or drive off the safety stands.
This may result in personal injury or
damage.
• Do not exceed 56 km/h (35 mph) when
spinning one drive· wheel with the other
drive wheel stopped. This limit is necessary
because the speedometer indicates only
one-half the actual wheel speed under these
conditions. If all drive wheels are spinning
at the same speed, do not exceed ·
112 km/h (70 mph). Personal injury may
result from excessive speed wheel
spinning. All persons should stay clear of
rotating components and balance weight
areas to avoid possible personal injury.
• When running an engine in the repair stall
for an extended period of time, use care
not to overheat the engine and
transmission.
2. When a test requires jacking up the vehicle
and running with the wheels and brake drum
removed:
• Do not apply the brake with the brake
drums removed.
• Do not place the transmission in Park with
the propeller shaft still spinning.
• Turn off the ignition to stop the powertrain
components from spinning.
Correcting Tire and Wheel Vibration
A first order tire and. wheel vibration is usually the
result of one of the following five conditions:
• Excessive radial runout
• Excessive lateral runout
• Excessive imbalance
• Excessive radial force variation
• Excessive lateral force variation
These conditions must be eliminated one at a time in
order to attain a set of tires that are free from
vibration causing elements. Substitute a set of tires
from another vehicle only as a last resort, and
only after the tires have been tested on a similar
vehicle under the same conditions. Correcting
the existing tire and wheel assemblies is the most
accurate and least time consuming approach. This is
due to vehicle-to-vehicle sensitivities and the
differences between the hubs of any two vehicles.
General Information
Methods Qf Measuring Tire/Wheel Assembly
Runout
The tire and wheel assembly runout will directly affect
the amount of the imbalance and the radial force
variation. Therefore, correct the runout first before
further diagnosis. The less runout, the less imbalance
and radial force variation. Radial and lateral runout
can be corrected at the same time. There are
two methods for correcting the tire and wheel
assembly runout:
• The on-vehicle method, with the tire and wheel
assembly mounted on the hub. The wheel
bearing must be in good condition.
• The off-vehicle method, with the tire and wheel
assembly mounted on a spin-type tire balancer.
Perform the following initial on-vehicle inspections
prior to the off-vehicle runout checks:
1. Inspect the tires for any uneven bead seatings.
The distance from the edge of the ring to the
concentric rim locating ring should be equal
around the entire circumference.
2. Properly mount the tires if the beads are not
seated properly in order to avoid excessive
runout and imbalance.
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The off-vehicle method is the easiest way of measuring
the tire and wheel runout. Properly mounting the
dial indicator in the correct location in relation to the
tire (1) is easier. The dial indicator is less likely to
be subjected to water, snow, dirt, or other elements.
After measuring the correct runout off-vehicle,
inspect the runout with the tire and wheel assembly
mounted on the vehicle. The runout measurement may
vary greatly between these two methods. If so, the
runout is due to one of the following conditions:
• Stud circle runout
• Hub flange runout
• A mounting problem between the wheel and the
vehicle
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