Caution: Failure to adhere to the following precautions before tire balancing
can result in personal injury or damage to components:
• | Clean away any dirt or deposits from the inside of the wheels. |
• | Remove any stones from the tread. |
• | Use coated weights on aluminum wheels. |
Important: On-vehicle balancing is not recommended on the Catera due to the silicone
injected front control arm bushings. Only off-vehicle balancing is recommended.
Tire and wheel balancers can drift out of calibration without warning,
or can become inaccurate as a result of abuse. The balancer calibration should
be inspected according to the manufacturer's requirements.
Tire Balancer Calibration Test
Important: Calibrate the tire balancer according to the manufacturer's recommendations,
or use the following procedure.
- Spin the balancer without a wheel or any of the adapters on the shaft.
- Inspect the balancer readings.
Specification
0-7 g (0.00-0.25 oz)
- Balance a tire and wheel assembly that is within radial and lateral
tolerances to ZERO.
- Add an 85 g (3 oz) test weight to the wheel at any
location.
- Spin the tire and wheel assembly again. Observe the readings.
• | In the static and dynamic modes, the balancer should call for
85 g (3 oz) 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. |
- With the assembly unbalanced to 85 g (3 oz), cycle
the balancer 5 times.
- Take the balancer readings:
Specification
Variation: 7 g (0.25 oz) or less
- Index the tire and wheel assembly at 4 separate locations
on the balancer shaft, 90 degrees apart.
- Cycle the balancer with the assembly at each location.
- Take the balancer readings:
Specification
Variation: 7 g (0.25 oz) or less
Tire Balancing Guidelines
Static and dynamic balance are the two kinds of tire/wheel
balance:
• | Static balance, also called
single plane balance, affects the distribution of weights around the wheel
circumference. |
• | Dynamic balance, or two-plane balance, affects the distribution
of weight on each side of the tire/wheel centerline. |
Most off-vehicle balancers can check both types of balance simultaneously.
As a general rule, most vehicles are more sensitive to static imbalance
than to dynamic imbalance. As little as 14-21 g (0.50-0.75 oz)
may induce 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, or shimmy.
• | Balance all 4 tires
as close to ZERO as possible. |
• | Carefully follow the wheel balancer manufacturer's instructions
for proper mounting techniques for different types of wheels. |
• | Aftermarket wheels, especially those incorporating universal lug
patterns, are potential sources of runout and mounting problems. |
• | Use the correct coated weights on aluminum wheels. |
• | Retest the tire and wheel assemblies for excessive runout after
correction and installation. |
• | 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,
consider these possibilities: |
- | Radial or lateral force variation |
Correcting On-Vehicle Imbalance
On-vehicle imbalance may result from components other than the tire
and wheel assemblies having imbalance. An on-vehicle high-speed balance or
replacement of suspected components may be necessary in order to correct
the condition.
Rotors do not have a set tolerance. However, rotors with more than 0.75 ounce
imbalance have the potential to cause vibration. The rotors can be inspected
for imbalance using either the on-vehicle or the off-vehicle method as
described below:
Checking Rotor Imbalance (Off-Vehicle)
- Measure the diameter and the width of the rotor.
- Mount the rotor on a balancer in the same manner as a wheel.
Important: The rotors can only be inspected for static imbalance. Ignore the dynamic
imbalance reading.
- Inspect for static imbalance and obvious deficiencies.