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: The tires can be balanced either on-vehicle or off-vehicle, but the
off-vehicle balancing procedures are recommended. Off-vehicle methods are
better because tire rotation will not affect the balancing. The off-vehicle
balancers are also more accurate than the on-vehicle balancers. Off-vehicle
balancers can perform dynamic balancing as well as static balancing.
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 every
two weeks, and whenever the readings are questionable.
Tire Balancing Guidelines
Static and dynamic balance are 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 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: |
| - | 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 (On-Vehicle)
- Support the rear of the vehicle on a suitable hoist. Refer to
Lifting and Jacking the Vehicle
in General Information.
- Remove the rear tire and wheel assemblies. Refer to
Wheel Installation
in Tires and Wheels.
Caution: One or more of the following guidelines may apply when performing specific required tests in the work stall:
| • | When a test requires spinning the drive wheels with the vehicle jacked up, adhere to the following precautions: |
| - | 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 vehicle speed under these conditions. Personal injury
may result from excessive wheel spinning. |
| - | If all of the drive wheels are spinning at the same speed, do not exceed 112 km/h (70 mph). Personal injury may result from excessive wheel spinning. |
| - | All persons should stay clear of the rotating components and the balance weight areas in order 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 the transmission. |
| • | When a test requires jacking up the vehicle and running with the wheels and brake rotors removed, adhere to the following precautions: |
| - | Support the suspension at normal ride height. |
| - | Do not apply the brake with the brake rotors removed. |
| - | Do not place the transmission in PARK with the drive axles spinning. |
| - | Turn Off the ignition in order to stop the powertrain components from spinning. |
| • | When running an engine in the work stall, use the exhaust removal system to prevent breathing dangerous gases. |
- Observe
the necessary safety precautions.
- Run the vehicle at the complaint speed while inspecting for vibration.
- If the vibration still exists, perform the following steps:
| 5.2. | Run the vehicle back to speed. |
- If the vibration is eliminated, perform the following steps:
| 6.2. | Perform the vibration test for each rotor. |
| 6.3. | Replace the rotor causing the imbalance. |
| 6.4. | Inspect the balance of the new rotor. |
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.
On-Vehicle Balancing Procedure
The vibration problem may not be correctable with the components removed
from the vehicle. An on-vehicle high-speed balancer may be required in order
to balance the tire and wheel assemblies while still mounted on the
vehicle. On-vehicle balancing will balance the hubs and the rotors simultaneously,
and will compensate for any residual runout encountered as a result
of mounting the tire and wheel assemblies on the vehicle as opposed
to off-vehicle balancing.
Follow the on-vehicle balancer manufacturer operator's manual for specific
instructions while keeping the following tips in mind:
Balancing Tips
| • | Do not remove the off-vehicle balancing weights. The purpose of
on-vehicle balance is to FINE TUNE the assembly balance already achieved,
not to start over again. |
| • | If the on-vehicle balance calls for more than 1 ounce of
additional weight, split the weight between the inboard and outboard flanges
of the wheel, so as not to upset the dynamic balance of the assembly
that was achieved in the off-vehicle balance. |
| • | An EVA vibration sensor placed on the fender of the vehicle during
the on-vehicle balance is an excellent indicator of the amplitude of the
vibration, and the effect that the balance has on the vibration. |
| • | Evaluate the vibration after the on-vehicle balance in order to
determine if the vibration condition has been resolved. |
Lateral Force Variation
Lateral force variation tends to deflect the vehicle sideway, or laterally.
Lateral force variation is based on the same concept as radial force variation.
A "snaky" belt inside the tire may be the cause of lateral
force. The tire substitution method may have to be used before tire
replacement.
A lateral force variation condition is rare. The best way to eliminate
lateral force variation as a factor in tire and wheel vibration conditions
is to ensure that the lateral runout of the tire and wheel assemblies
is at an absolute minimum.
The vehicle will "wobble" or "waddle"
at slow speeds of 8-40 km/h (5-25 mph) when lateral
force variation is excessive. This condition is usually related to
the first-order of tire and wheel rotation.
Wheel Hub/Axle Flange Runout
Inspect the wheel hub/axle flange when lateral runout occurs during
on-vehicle testing but not during off-vehicle testing. Use the tolerances
described here only as guidelines. Perform corrections only if the
runout cannot be brought to within tolerance.
- Position the dial indicator on the machined surface of the following
components outside of the wheel studs:
- Rotate the hub in order to find the low spot.
- Set the dial indicator to zero at the low spot.
- Rotate the hub again while inspecting the runout.
Specification
Runout tolerance: 0.132 mm (0.0052 in)
Wheel Stud (Stud Circle) Runout
Use the following procedure whenever the off-vehicle radial runout and
the on-vehicle radial runout are significantly different, and the
tire and
wheel vibration condition has not been corrected.
- Position the dial indicator in order to contact the wheel mounting
studs.
- Measure the stud runout as close to the flange as possible.
- Turn the hub to register on each of the studs.
- Zero the dial indicator on the lowest stud.
- Inspect the total runout.
Specification
Runout tolerance: 0.25 mm (0.010 in)
