Wheel Alignment Tips
Have your Wheel Alignment checked every 15,000 miles and always when installing new tires. Wheel alignment sometimes referred to as tracking, is part of standard automobile maintenance that consists of adjusting the angles of the wheels so that they are set to the car maker's specification. The purpose of these adjustments is to reduce tire wear, and to ensure that vehicle travel, is straight and true. Alignment angles can also be altered beyond the maker's specifications to obtain a specific handling characteristic. Motorsport and off-road applications may call for angles to be adjusted well beyond "normal" for a variety of reasons.
The primary angles are the basic angle alignment of the wheels relative to each other and to the car body. These adjustments are the camber, caster and toe. On some cars, not all of these can be adjusted on every wheel.
These three parameters can be further categorized into front and rear. The parameters are:
- Front: Camber (right & left)
- Front: Toe (left, right & total)
- Front: Caster (left & right)
- Rear: Camber (left & right)
- Rear: Toe (left, right & total)
- Rear: Thrust angle
- Rear: Caster (left & right)
The secondary angles include numerous other adjustments, such as:
SAI (left & right)
- Included angle (left & right)
- Toe out on turns (left & right)
- Maximum turns (left & right)
- Toe curve change (left & right)
- Track width difference
- Wheelbase difference
- Front ride height (left & right)
- Rear ride height (left & right)
- Frame angle
Setback (front & rear) is often referred as a wheel alignment angle. However setback simply exists because of the measuring system and does not have any specification from car manufacturers.
A target called a "head" is attached to a specially designed clamp which holds on to a wheel. Often with alignment equipment, these "heads" can be a large precision reflector. In this case, the alignment "tower" contains the cameras as well as arrays of LEDs. This system flashes one array of LEDs for each reflector whilst a camera centrally located in the LED array "looks for" an image of the reflectors patterned face.
The steering angle sensor (SAS) is a critical part of the ESC system that measures the steering wheel position angle and rate of turn. A scan tool can be used to obtain this data in degrees. The SAS is located in a sensor cluster in the steering column.
Resetting Steering Angle Sensors
Many vehicles require the SAS be reset or recalibrated after an alignment is performed or parts in the steering system are replaced. There are three types of reset procedures, systems that self calibrate on their own, vehicles that require specific wires or buttons be pressed, and systems that require recalibration with a scan tool. If the SAS is out of calibration, most vehicles can tell if they are traveling in a straight line, but if the angle is too far off, the ESC could become disabled.