Lateral Force

In the period of keeping E-211 NISSAN Skyline experienced I some very important physical steering property when I repositioned rear main bar bushes on both side. Following the Car Graphic report on the Nissan IRS in combination with Fair Lady Z, 90 degree different of clacking position. I did it with some determination to replace them in E211 as same as S130 Fairlady Z model.

Thank to the suppression of lateral movement of rear main bar while turning, the steering astringency had far improved like a completely different vehicle. I had realized that the the lateral compliance on rear axle construction affects so much on steering reaction, too much compliance leads to dull, muddy and sticky character.

And tens year later, exactly the same experiment was performed on EP82 TOYOTA Starlet with 3 links rigid axle in combination with lateral rod support, remembering a very special designing of the direction of the rod positioning, parallel to the ground while no burdening, not with oblique direction.

The way of experiments are like these, tapered frontal and rear bushes are fixed in loosened position, positioned but with very soft compliance condition, so the rear fixed and rigid axle relatively easily moves to lateral direction.

In this condition the force from steering rotation  is easily consumed like nothing and after finishing the deformation in softer property the force would be communicated. In another words the dead zone would be clearly appears in steering centric position. The driver would be bored immediately because of dull steering reaction.

Judging from two examples, the lateral displacement and so to speak lateral compliance in rear axle designing have most to do with the dynamic movement of the vehicle especially in the riding taste from the steering reaction.
These are why I deny Torsion Beam rear axle designing based on the distorting and displacing concepts, especially for a sports car or a sports grade model.