Ford 2003 Mustang Workshop Manual page 132

Shimmy
Shimmy, as observed by the driver, is large, consistent, rotational oscillations of the steering wheel
resulting from large, side-to-side (lateral) tire/wheel movements.
Shimmy is usually experienced near 64 km/h (40 mph), and can begin or be amplified when the tire
contacts pot holes or irregularities in the road surface.
Nibble
Sometimes confused with shimmy, nibble is a condition resulting from tire interaction with various road
surfaces and observed by the driver as small rotational oscillations of the steering wheel.
Poor Returnability/Sticky Steering
Poor returnability and sticky steering is used to describe the poor return of the steering wheel to center
after a turn or steering correction is completed.
Drift/Pull
Pull is a tugging sensation, felt in the steering wheel, that must be overcome to keep the vehicle going
straight.
Drift describes what a vehicle with this condition does with hands off the steering wheel.
Drift/pull may be induced by conditions external to the vehicle (i.e., wind, road camber).
Poor Groove Feel
Poor groove feel is characterized by little or no buildup of turning effort felt in the steering wheel as the
wheel is rocked slowly left and right within very small turns around center or straight-ahead (under 20
degrees of steering wheel turn). Efforts may be said to be "flat on center."
Under 20 degrees of turn, most of the turning effort that builds up comes from the mesh of gear
teeth in the steering gear (3504). In this range, the steering wheel is not yet turned enough to
feel the effort from the self-aligning forces at the road wheel or tire patch.
In the diagnosis of a handling problem, it is important to understand the difference between
wander and poor groove feel.