GMC Chevrolet Camaro 1998 Service Manual page 79

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General. Information
Tire Balancer Calibration Test
1 . Spin the balancer without a wheel or any of the
adapters on the shaft.
2. Inspect the balancer readings.
Specification
0.00-0.25 oz
3. Balance a tire and wheel assembly that is within
radial and lateral tolerances to ZERO.
4. Add a 3 ounce test weight to the wheel at any
location.
5. Spin the tire and wheel assembly again, noting
the readings. ·
• In the static and dynamic modes, the balancer
should call for 3 ounces of weight, 180 degrees
opposite the test weight.
• In the dynamic mode only, the weight should
be called for on the flange of the wheel
opposite the last weight.
6. With the assembly unbalanced to 3 ounces, cycle
the balancer 5 times.
7. Take the balancer readings:
Specification
Variation: 0.25 oz or less
8. Index the tire and wheel assembly at four separate
locations on the balancer shaft, 90 degrees apart.
9. Cycle the balancer with the assembly at
each location.
10. Take the balancer readings:
Specification
Variation: 0.25.oz or less
Tire Balancing Guidelines
Static and dynamic balance are two kinds of tire/wheel
balance:
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• Static balance, also called single plane balance,
affects the distribution of weights around the
wheel circumference.
Vibration Diagnosis and Correction 0-67
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• Dynamic balance, or two-plane balance, affects
the distribution of weight on each side of the
tire/wheel centerline.
Most off-vehicle balancers are capable of checking
both types of balance simultaneously.
As a general rule, most vehicles are more sensitive to
static imbalance than to dynamic imbalance, with
as little as 0.50-0.75 oz capable of inducing a vibration
in some vehicles. Vibration induced by static
imbalance will cause a vertical or BOUNCING motion
of the tire.
Dynamic imbalance results in a side-to-side motion of
the tire. This motion is referred to as SHIMMY.
• Balance all four tires as close to ZERO as
possible.
• Carefully follow the wheel balancer manufacturer's
instructions for proper mounting techniques to be
used on different types of wheels.
• Regard aftermarket wheels, especially those
incorporating universal lug patterns, as potential
sources of runout and mounting problems.
• Use the correct coated weights on aluminum
wheels.
• Recheck the tire and wheel assemblies for
excessive runout after they have been corrected
and installed.
• Evaluate the vehicle at the complaint speed and
note if the vibration has been corrected.
• If the vibration is still present, or is reduced but
still unacceptable, you may find one of two
possibilities:
- On-vehicle imbalance
- Radial or lateral force variation