Steering Geometry

1. Negative caster is undesieable because it tends to aid the turning moment.This results in oversteer condition and destabilizes the vehicle.

2. Even though certain amount of positive caster increases the steering effort and provides directional stability, too much positive caster will tend to make the steering heavy.

This eesults in understeer condition.

3. High kingpin lateral offset results in a condition called Torque Steer.

Torque Steer induces undesired additional torque in steering due to uneven driving forces.

4. For reverse Ackermann, the outer wheel steers lesser than inner wheels.

5. Given: distance of turn center from front axle, x=4000mm

Wheel base=2700mm

%Ackermann = (wheel base/x)

%Ackermann = 2700/4000 = 0.675

%Ackermann = 67.5%

6. Revoknuckle geometry makes use of modified version of McPherson strut suspension in which steer axis is offset from strut axis towards the wheel center. This reduces the kingpin lateral offset/spindle length which in turn reduces the imblance in torque delivery.

Thereby the torque steer is reduced.

7. The two types of tierod errors with respect to ride steer are:

1. Tierod length error

Effect:

It leads to a curved ride steer plot.

If the tierod length is smaller than what is required, then the wheels to out in both jounce and rebound.

Conversely, if the tierod length is larger than what is required, then the wheels would to out in jounce and rebound.

b. Tierod angle error

Effect:

It leads to linear but sloped ride steer plot.

If the tierod is below the point on line joining the pivot points, the outer front wheel toes out and inner front wheel toes in.

But if the tirod is above the point on line joining the pivot points, the outer front wheel toes in and inner front wheel toes out.