Alignment: Description and Operation

Wheel Alignment Angles

NOTE: When making rear alignment adjustments, it is important to know that when adjustments are made to the rear toe, the rear camber will also be adjusted (in the same direction as the toe adjustment). When making adjustments to the rear camber, the rear toe will also be adjusted (in the opposite direction of the camber adjustment). It will be necessary to check the rear camber whenever rear toe adjustments are made and to check the rear toe whenever rear camber adjustments are made.

Front toe is adjusted through the use of adjustable tie-rod ends. Front camber is adjusted through the use of the upper strut plate. Rotating the upper strut plate 180 degrees will change the camber +0.4 degrees. Front caster is not adjustable on the vehicle. Rear toe is adjusted through the use of adjustable toe link cams. Rear camber is adjusted through the use of a cam bolt that attaches the rear lower control arm to the rear subframe.

Camber

Negative and Positive Camber





Camber is the vertical tilt of the wheel when viewed from the front. Camber can be positive or negative and has a direct affect on tire wear.

Caster










Caster is the deviation from vertical of an imaginary line drawn through the ball joints when viewed from the side. The caster specifications will give the vehicle the best directional stability characteristics when loaded and driven. The caster setting is not related to tire wear.

Toe

Positive Toe (Toe In)





Negative Toe (Toe Out)





The vehicle toe setting affects tire wear and directional stability.

Incorrect Thrust Angle (Dogtracking)










Incorrect thrust angle (also known as dogtracking) is the condition in which the rear axle is not square to the chassis. Heavily crowned roads can give the illusion of dogtracking.

Wander

Wander is the tendency of the vehicle to require frequent, random left and right steering wheel corrections to maintain a straight path down a level road.

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. For wheel and tire diagnosis, refer to Wheels and Tires.

Poor Returnability/Sticky Steering

Poor returnability and sticky steering is used to describe poor return of the steering wheel to center after a turn or steering correction.

Drift/Pull

Pull is a tugging sensation, felt by the hands on 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.

- A vehicle-related drift/pull, on a flat road, will cause a consistent deviation from the straight-ahead path and require constant steering input in the opposite direction to counteract the effect.

- Drift/pull may be induced by conditions external to the vehicle (for example, wind, road crown).

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. 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 roadability problem, it is important to understand the difference between wander and poor groove feel.