Tire And Wheel Vibration; Tire And Wheel Runout Measurement - GMC Chevrolet Camaro 1998 Service Manual

0-52 Vibration Diagnosis and Correction
Sometimes, the tire/wheel vibration may be of a
higher-order. In order to compute possible higher-order
vibrations, multiply the rotational speed of the tires
in Hertz at the complaint speed by the order number.
If any of these matches the vibration frequency,
then a vibration of that particular order is present in
one of the tire and wheel assemblies.
Steering and Suspension Assembly Vibrations
Steering and suspension assembly vibrations are
the first level of testing for low-frequency vibrations that
are vehicle-speed sensitive. The symptoms if a
steering/suspension first-order vibration are shimmy or
shake, usually felt in the steering wheel or in the
seat. Inspect the following components for wear or
damage:
• The steering tie rod ends.
• The suspension ball joints.
Tire and Wheel Vibration
Tire and wheel assembly vibrations are the next level
of testing for low-frequency vibrations that are
vehicle speed sensitive. The tires, wheels, brake
rotors and wheel hubs should be systematically tested,
according to the symptoms.
First-Order Tire and Wheel Assembly Vibration
The following are symptoms of first-order vibrations
caused by tire and wheel assemblies:
• The vibration is always vehicle-speed related.
If the vibration is affected by the speed of
the engine, or is eliminated by placing the
transmission in NEUTRAL, then the vibration is
not related to the tire and wheel assemblies.
• The vibration will feel like a SHAKE, usually in the
steering wheel or the seat:
- Tire and wheel vibrations that are felt in the
steering wheel are most likely related to the
front tire and wheel assemblies.
- Tire and wheel vibrations that are felt in the
seat or the floor are most likely related to
the rear tire and wheel assemblies.
This may not always hold true, but is a general
rule that may serve to initially isolate a
problem to the front or the rear of the vehicle.
• The customer may complain of a WADDLE at low
speeds of 8 to 56 km/h (5 to 35 mph).
• The frequency on the EVA will correspond to the
first-order of tire rotation. This frequency will
usually be in the 1 O to 20 Hz range, depending on
the speed of the complaint and the size of the
tire. The smaller the tire, the faster it will rotate at
any given speed.
• The range of the human ear begins at 20 Hz. For
this reason, first-order tire vibrations are rarely
produce noise. The exception to this would be if
the tires display an irregular tread pattern or
flat spots, causing a GROWLING or
SLAPPING noise.
General Information
Tire and Wheel Runout Measurement
Measure wheel runout with an accurate dial indicator.
Measure with the wheel installed or with the wheel
off of the vehicle .. Use an accurate mounting surface
such as a wheel balancer. You can measure with
or without the tire mounted on the wheel.
Measure radial runout and lateral runout on the
inboard and outboard rim flanges. With the dial
indicator in position, rotate the wheel slowly one
revolution. Record the total indicator reading. If any
measurement exceeds the specifications, and if there
is a vibration that wheel balancing does not correct,
replace the wheel. Disregard any indicator readings
that are due to welds, paint runs, or scratches.
Radial Runout
Legend
(1) Dial Indicator
(2) High Spot
(3) Low Spot
Unlike a perfect circle, the tire shape of radial runout
is oval. Measure radial tire runout from the center
tire tread rib. You can measure other tread ribs. The
gauge reads the total runout. The high spot is the
location of the maximum runout. If either flange
is beyond specifications, replace the rim.
• Aluminum Wheels - 0.762 mm (0.030 in)
• Steel Wheels - 1.015 mm (0.040 in)
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