Alignment: Description and Operation
DESCRIPTION AND OPERATIONWheel Alignment Angles
Camber, caster and toe are adjustable for the front suspension system. The front camber and caster are adjusted by first aligning the subframe and, if necessary, by resetting the alignment plates on the shock towers. The front toe is adjusted by the use of the front wheel spindle tie-rod.
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 effect 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.
^ must be checked after adding aftermarket equipment, such as a snowplow or body.
Ride Height
Front Ride Height Measurement
Rear Ride Height Measurement
Wheel Track
Dogtracking
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.
Poor Returnability/Sticky Steering
Poor returnability and sticky steering are 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 readability problem, it is important to understand the difference between wander and poor groove feel.
Low Tire Warning (LTW) System
The Low Tire Warning (LTW) system detects differences in inflation pressures in one or more tires. The system uses the ABS wheel speed sensors to monitor the rolling radius of the wheel and tire assemblies. If a difference in rolling radius is detected, the ABS module illuminates the LTW lamp located in the instrument cluster.
Low Tire Warning (LTW) System Resetting
The LTW system must be reset when tire replacement, maintenance or system repair is performed or any time tire pressure is adjusted.
Vehicles Without Message Center
To reset the system, press and hold the odometer reset button and wait for the TIRE PRESSURE SET light to illuminate. Continue to press the button for 3 seconds, then release. After 3 seconds, the low tire pressure warning lamp will flash 3 times, indicating that the low tire warning system reset procedure is complete.
Vehicles With Message Center
To reset the system, press and hold the SETUP button and wait for the message center to display REST FOR SYSTEM CHECK. Then press the RESET button and wait for the message center to display HOLD RESET TO RELEARN . Press and hold the RESET button for 3 seconds. The message HOLD RESET TO RELEARN and the low tire warning lamp will flash 3 times, indicating the reset procedure is complete.
If the lamp illuminates, reset the tire pressure to specification before resetting the system. If the problem persists, go to the Symptom Chart.
The LTW system is not capable of detecting rapid loss of inflation. The system may not detect loss of inflation in more than one tire.
The LTW system can be deactivated.