Wheel alignment
Encyclopedia
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 (without "pulling" to one side). 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.
, 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, so summarily the parameters are:
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.
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. These cameras perform the same function as the other style of alignment equipment, yet alleviate numerous issues prone to relocating a heavy precision camera assembly on each vehicle serviced.
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
maintenance
Car maintenance
Auto maintenance describes the act of inspecting or testing the condition of car subsystems and servicing or replacing parts and fluids....
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
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
wear, and to ensure that vehicle travel is straight and true (without "pulling" to one side). 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.
Primary angles
The primary angles are the basic angle alignment of the wheels relative to each other and to the car body. These adjustments are the camberCamber angle
thumb|100px|From the front of the car, a right wheel with a negative camber angleCamber angle is the angle made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of the wheels used for steering and the vertical axis of the vehicle when viewed from the front or...
, caster
Caster angle
thumb|250px|θ is the caster angle, the red line is the pivot line, and the grey area is the tire.Caster angle or castor angle is the angular displacement from the vertical axis of the suspension of a steered wheel in a car, bicycle or other vehicle, measured in the longitudinal direction...
and toe
Toe (automotive)
In automotive engineering, toe, also known as tracking, is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with steer, which is the antisymmetric angle, i.e. both...
. On some cars, not all of these can be adjusted on every wheel.
These three parameters can be further categorized into front and rear, so summarily the parameters are:
- Front: Caster (left & right)
- Front: Camber (left & right)
- Front: Toe (left, right & total)
- Rear: Camber (left & right)
- Rear: Toe (left, right & total)
- Rear: Thrust angle
Secondary angles
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.
Measurement
A camera unit (sometimes called a "head") is attached to a specially designed clamp which holds on to a wheel. There are usually four camera units in a wheel alignment system (a camera unit for each wheel). The camera units communicate their physical positioning with respect to other camera units to a central computer which calculates and displays how much the camber, toe and caster are misaligned.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. These cameras perform the same function as the other style of alignment equipment, yet alleviate numerous issues prone to relocating a heavy precision camera assembly on each vehicle serviced.
See also
- Car handlingCar handlingAutomobile handling and vehicle handling are descriptions of the way wheeled vehicles perform transverse to their direction of motion, particularly during cornering and swerving. It also includes their stability when moving at rest. Handling and braking are the major components of a vehicle's...
- Car maintenanceCar maintenanceAuto maintenance describes the act of inspecting or testing the condition of car subsystems and servicing or replacing parts and fluids....
- Auto mechanicAuto mechanicAn auto mechanic is a mechanic with a variety of car makes or either in a specific area or in a specific make of car. In repairing cars, their main role is to diagnose the problem accurately and quickly...
- Tire rotationTire rotationTire rotation or rotating tires is the practice of moving automobile wheels and tires from one position on the car, to another, to ensure even tire wear. Tire wear is uneven for any number of reasons...
- Tire balanceTire balanceTire balance, also referred to as tire unbalance or imbalance, describes the distribution of mass within an automobile tire or the wheel to which it is attached. When the tire rotates, asymmetries of mass cause the wheel to wobble, which can cause ride disturbances, usually vertical and lateral...
- ASEAutomotive Service ExcellenceNational Institute for Automotive Service Excellence is a professional certification group that certifies professionals in the automotive repair and service industry. It is an independent, non-profit organization created in 1972 in response to consumers wanting the need to distinguish between...