Steering character

As I mentioned yesterday, lateral displacement on rear axle does affect on the steering response and on the taste of ride so much, so we cannot discus on steering characteristic response including straight and curvature running focusing only on the steering constructive designing and construction, axle compliance setting also. The stability, the edge of rising, the transient and the convergence are the element of the character I wanna put an emphasis on.
The resistance power against the lateral force on rear axle plays a great part of the character of steering response as I wrote several times here, but the fixation of the construction would invite the reduction of compliance effect at the same time. The difficulty of designing exists here, probably many a factory designer must exert themselves in this setting by desperate effort for the new model?

On the rear beam axle designing like NCP10 TOYOTA Vitz, very new and sophisticated concept is introduced in order to relieve the shock and vibration from the ground by deform a trailing arm bush itself utilizing physical phenomena of class 2 lever action at beginning phase, supporting axle coil spring acts as a supporting point while the hinge bush is deforming at 6 o'clock position and finishing the distortion the bush acts as a supporting point transits to class 1 lever action.
Consequently, the bush inserted in beam axle construction is designed to be movable intentionally, this is why the steering character of automobiles with beam axle designing have a tendency to be dull, muddy and sleepy keeping a distance from good astringent steering character.

The charcters of steering reaction were very similar with each other, the reason was not the designing of concepts as a world car strategy but the movable rear axle condition at all.
Though it might be very difficult to make Vitz better in steering character, I will try to do that in very near future. Remember that the special rubber parts from TRD are already set in rear bush portion, still not enough effective.