Wheels/Tires - Vibrations
Group: 44Number: 94-03
Date: Aug, 1, 1994
Subject:
Wheels/Tires, Eliminating Vibrations
Model(s): All All m.y.
Wheel imbalance generates dynamic forces that can cause vehicle components such as steering gear, wheel suspension units, and body to resonate. This in turn, leads to vibrations of the steering gear and the vehicle itself.
Before making any repairs:
- Check tire pressures and correct if necessary
- Road test vehicle to determine the type of condition (steering wheel wobble and affected speed range) so a comparison check can be made later to prove repairs have been successful.
Note:
Vibration can fluctuate as left and right tires phase in and out
- Check that surfaces of tires are free of damage such as scuffing and flat areas.
- Check that suspension components are not damaged or worn.
Note:
If a component is replaced, check and align front suspension as necessary
- Clean wheels and tires of accumulated mud or dirt
Caution!
Even a small amount of imbalance in the wheels can lead to steering wobble. Great care must be taken with all operations dealing with the elimination of imbalance.
Work Sequence
Check radial and lateral runout of both steel and alloy wheel and tire assemblies as follows:
Note:
Peak readings, up or down, which are caused by small imperfections on tire surface should be ignored
^ Maximum radial runout: 0.8 mm (0.032 in.)
Set up the dial gauge so that needle is just making contact with center of tire wall. Slowly rotate the wheel by hand; read off needle deflection
^ Maximum lateral runout: 1.2 mm (0.047 in.)
If radial and lateral runout figures are within prescribed limits, remove existing balance weights and balance wheels.
Caution
Wheels MUST be mounted with same centering method as on vehicle (i.e., bolted to hub/arbor) and centered on a cylindrical (not conical) surface.
If radial and/or lateral runout is excessive, correct as follows:
- Mark highest point of needle deflection on tire
- Deflate tire and push tire beads down into wheel bed
- Rotate tire 180° on wheel
- Check for and remove any foreign material from inside tire (e.g., water)
- Inflate tire and recheck radial runout
If maximum figures are still outside prescribed limits:
- Rotate tire a further 90° on wheel and check again
If figures are still outside limits:
- Check radial and lateral runout of the wheel at both flanges (install wheel without tire on balancing machine or on vehicle)
Maximum allowed values
Note:
Peak readings, up and down, which are cause by small imperfections on wheel surface should be ignored.
If maximum tolerances are exceeded, replace wheel, and dynamically balance tire/wheel assembly.
- Install wheels with least amount of radial runout at the front. Tighten wheel bolts by hand
- Measure radial runout. Mark highest point of runout and turn this part of tire downward
- Lower vehicle to ground and tighten wheel bolts to prescribed torque
- Road test vehicle
^ If wobble (imbalance) still occurs, radial or lateral oscillations of one or more tires are too high. (This cannot be measured with normal workshop equipment)
In such cases, either front or rear tires should be replaced in pairs.