What is Toe in and Toe out | Definition | Effect

Definition : 

Toe-in is the amount by which the front wheels are mounted closer together on the front than on the back when the vehicle is stationary and viewed from the top. The wheel can be set closer to the rear than to the front, in which case the difference of the distances between the front and rear wheels is called toe-out. 

Effect : 

In rear-wheel-drive vehicles, there is usually an inherent tendency for the wheels to toe-out due to purposeful deviation from centre point steering due to errors in the steering angles of the inner and outer bends of the wheels. 

There is usually an inherent tendency for the wheels to toe-out in rear-wheel drive vehicles just because of purposeful deviation from centre point steering due to errors in steering angles of the inner and outer wheels bends. In order to compensate for this tendency, a small amount of toe-in was initially provided in such vehicles so that the wheels move perfectly straight ahead under normal turning condition. However, the initial toe-out was provided in the case of some front-wheel-drive vehicles to counter the toe-in present therein. 

In rear-wheel-drive vehicles, due to errors in the steering angles of the inner and outer bends of the wheels, there is usually an inherent tendency for the wheels to toe out. 

In rear-wheel-drive vehicles, there is usually an inherent tendency for the wheels to toe out due to purposeful deviation from centre point steering due to errors in the steering angles of the inner and outer bends of the wheels. A small amount of toe-in was initially provided in such vehicles to compensate for this tendency so that the wheels move perfectly straight ahead under the normal turning conditions. 

Toe-in generally does not exceed 3 mm. 

A toe-in wheel alignment can help to reduce oversteer problems and increase stability in front-wheel drives vehicles. 

A toe-out alignment can help to mitigate issues related to understeering and can improve the handling of a vehicle that has rear-wheel drive. 

Explore more information: 

1. What is a caster?

What is caster | Definition | Effect

Definition : 

The caster angle is called the angle between the kingpin centre line for the steering axis and the vertical in the wheel plane. 

If the centre line of the kingpin meets the ground at a point ahead of the verticle wheel centre line is called the positive caster and if it is behind the verticle wheel centre line is called the negative caster. 

Effect : 

The steering axis pulls the front tires, while the tire drag due to the weight of the vehicle is on the vertical line in the centre of the footprint. Since the positive caster steering axis would meet the ground ahead of the tire print centre, the later would always follow former, thus positive caster provides directional stability on the car wheels. 

A positive caster increases the effort required to turn the steering wheel. In the case of negative caster steering, it may be noted that it would be unstable. Example -There would be poor directional control, as in this case the centre of the tire print leads the steering axis. Extremely negative casters would cause shimmy and consequently cupped wear of the front tires. 

As the change of caster angle, the other angles of the steering geometry, the chamber, the inclination of the kingpin and the toe0in or toe-out are changed. Therefore, it is very important that this angle is adjusted first of all while doing the adjustment job. 

Approximately 3 degrees of castor gives good results. 

Explore more information:

1. Difference between caster and camber