Balancing Theory - Couple Imbalance
Dynamic imbalance is defined as a condition where one or more locations of the
tire/wheel assembly are heavier causing an imbalance force and/or an imbalance
shake and wobble. Shown below is a tire/wheel assembly with two heavy spots of
equal weight which are located 180 degrees radically from each other on opposite
sides. As this assembly rotates, centrifugal forces cause a large imbalance wobble to
be created, but the imbalance force (as well as the static imbalance) will be zero. A
wheel with this condition will cause a wobble or shimmy to be felt in the steering
wheel. Excessive dynamic imbalance of this type creates a shimmy that transfers
through the suspension components to the occupants of the vehicle, especially at
higher speeds.
IMBALANCE WOBBLE
(LATERAL TWIST OR TORQUE)
FRONT VIEW
ZERO STATIC IMBALANCE WITH LARGE
COUPLE IMBALANCE
Modern “dynamic” balancers spin the wheel in order to measure both the up and
down static imbalance force and couple wobble or shimmy related imbalance (side-
to-side).
Dynamic balancers direct the operator to place correction weights on the inside and
outside correction locations of the rim, or a single weight away from the center of the
wheel, so that both imbalance shake (static) and imbalance wobble (couple) will be
eliminated.
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Introduction to Balancing GSP9720JLR Wheel Balancer Operation Instructions
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