Adams Assignments – Problem 4 – Steering geometry 2

Double wishbone assembly was selected and hardpoints were modified to achieve the target results.

Caster angle

Caster angle (Original): 5.37deg

Caster angle (Modified): 4.00deg

Effects:

Steering effort is reduced, straight-line stability and jacking effect are slightly reduced.

Caster moment arm

Caster moment arm (Original): 8.57mm

Caster moment arm (Modified): 21mm

Effects:

Self-centering torque in the steering system is increased.

KPI angle

KPI angle (Original): 10.07 deg

KPI angle (Modified): 13.00 deg

Effects:

Self-centering torque is increased.

Steer axis offset (Resultant)

Steer axis offset (Original): 85.77mm

Steer axis offset (Modified): 84.76mm

Effects:

No major change. Torque steer is slightly reduced.

Steer axis longitudinal offset

Steer axis longitudinal offset (Original): -18.74mm

Steer axis longitudinal offset (Modified): 0.64mm

Effects:

Stability of the vehicle is increased.

Scrub radius

Scrub radius (Original): 33.80mm

Scrub radius (Modified): 20mm

Effects:

Steering effort is reduced.

No, all these parameters cannot be controlled independently. Parameters were modified by adjusting the outer ball joint's hardpoints. If we modify the caster angle, it will change our caster moment arm and kingpin longitudinal offset. We can modify the caster moment arm without affecting our caster angle but it will change our kingpin longitudinal offset. If we modify the KPI angle, it will change our kingpin lateral offset and scrub radius. We can modify the kingpin lateral offset or scrub radius without affecting the KPI angle but they will affect each other.