Alignment: Description and Operation
Suspension SystemThe front caster and camber are adjusted by means of removing set shims at the upper control arm-to-frame mounting bolts and installing washers (W-705040-S426) to allow the arm to be adjusted in the frame slots. A caster split adjustment can be made by turning an adjustment bolt located on the RH lower arm rearward frame mountings. Front toe is adjusted by the use of the front wheel spindle tie rod. The rear camber is adjusted by removing the set shim from the rearward lower control arm to frame mounting bolt and installing a washer (W-705040-S426) to allow the arm to be adjusted in the frame slot. The rear toe is adjusted by the use of the rear toe link.
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 in this information 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 (Top 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 is used to describe the poor return of the steering wheel to center after a turn or the steering correction is completed.
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, such as wind or road camber.
Tire Pressure Monitoring System (TPMS)
The optional Tire Pressure Monitoring System (TPMS) has the ability to monitor the air pressure of the four road tires. The tire-mounted pressure sensors transmit signals to the TPMS module by using the valve stem as an antenna. These transmissions are sent approximately every 30 seconds when the vehicle speed exceeds 32 km/h (20 mph). The TPMS module compares each tire pressure sensor transmission against two pressure limits-low and high. If the TPMS module determines that the tire pressure has exceeded the low or high limit, the TPMS module communicates on the SCP network to the vehicle message center, which then displays a warning message.