Wheel Alignment

Procedure that enhances the performance and longevity of vehicle Tyres. The wheels are said to be out of alignment when the suspension and steering system is not operating at their desired angles causing wear and tear of suspension parts due to impact with puddles

Indications of misalignment

• Irregular Tyre wear
• Handling problems
• Crooked steering wheel

Camber angle-

When watching from front of the car if the wheels are not perpendicular to the ground than wheels are said to have camber angle. If the distance between top of the wheels is greater than bottom of wheels the camber angle is said to be positive vice versa for negative camber

Benefits

• Negative camber is beneficial in racing and formula cars. If positive camber will be set in such cars then the car will try to roll during the cornering.
• Positive camber is beneficial in passenger or commercial vehicles. Such vehicles are made for carrying passenger or goods load. The weight over them straightens the positive camber hence increasing the grip of Tyre with road.

Steering axis inclination (SAI) OR kingpin inclination

When watching from front of the car if the axis of wheels are not perpendicular to the ground than its said to have SAI angle

Benefits

• Decreases the scrub radius on the contact point of the Tyres hence decreasing steering effort and Tyre wear
• Self straightening of wheels when steering is released-Due to SAI when wheels are turned they lift the car a little hence resisting the wheel turning by the weight that is lifted

Toe Angle

When watching vehicle from the top if the wheel are not parallel to each other they are said to have toe angle. If the wheels point toward the centre line of vehicle the angle is said to be positive toe or toe-in and if the wheels point away from the centre of vehicle the angle is said to be negative toe or toe-out.

Toe-in benefits

Toe-in is usually kept in RWD cars to prevent the problem of Fishtailing or over steer it keeps the car stable in the straight line on straight path (straight line stability). Also at the time of cornering the body roll transfers weight to exterior Tyres. Thus due to SAI angle (steer straightening by weight) the Exterior Tyre straighten in the direction of turning hence reducing turning ability. This is the reason most street cars have toe-in adjustment as we don’t need instant turning in such vehicles.

Toe-out benefits 

Toe-out is usually kept in FWD cars as the front Tyres thrust in direction they are pointing creating the moment inward due to the suspension arm thus straightens the wheels while vehicle is in motion. Also it can increase the turning force during cornering. The inside Tyre will generate drag force which creates the torque on the whole car and help turn it in the correct direction. So the problem of under steer (usually in racing cars) can be cured.

Caster Angle

Angle of steering axis with respect to the vertical axis, when looking from the side of the vehicle. If the angle will be toward back of the car or the steering axis touches the ground in-front of the Tyre's contact patch (lead point) this caster angle is called as positive caster. Similarly, if the angle will toward front of the car or the steering axis touches the ground behind the Tyre's contact patch this caster angle is called as negative caster

Pros and cons of caster

The positive caster tends to straighten the wheels when they are travelling forward due the moment created at Tyre's contact patch by the force at lead point. Thus gives the vehicle straight line stability. The excessive caster angle can increase the steering effort

Negative caster can cause the vehicle to have poor directional stability, make it tend wander and not return to centre.