Torsion beam axle suspension

Rear suspension arm sheet is the name of the special parts provided by TRD(Toyota Racing Division) for NCP10 Vitz. They are some racing parts for controlling the lateral movement of rear torsion beam arm suspension, as TOYOTA calls the inevitable physical phenomena with a very beautiful name "Toe Correct System" ?

This unacceptable strange movement of rear axle causes sticky steering action that's unendurable. Initial steering movement is completely consumed by the unnecessary lateral movement of rear suspension, in other word, broad dead zone is produced by the rear axle movement, that's called as toe control system?

So TRD is providing the countermeasure for this strange phenomena, actually this is very inconvenient if NCP10 Vitz is used at some racing speed. Uncontrollable because of strange reaction that unexpectedly guides the car undesired direction with tricky action.
In additional to the other words, the parts is designed to eliminate so to speak "Free movement area" , for racing use requiring relatively precise movement of rear axle.

Depending on my own experience strange "Toe Correct System" habit still remains after wearing those special parts, 10mm thickness butyl rubber parts with probably #70 ISO hardness. Thrust bearing application there is the better way to prevent the lateral movement effectively.

Basically those upper problem have been clear after the change of design concept of lower suspension arms no matter how if they are for front or for rear, by changing arm stress lever ratios.
This concept is based on the deformable bushes application on the hinge movement portions with the concept to distort and to deform actively to consume physical stress from the ground.

Naturally the geometry of axle distorted causing the change of wheel alignment. Most of the driver would feel some unnatural sticky steering reaction at the beginning, but most of them would get accustomed to the steering feel as a specific habit of the model NCP10 Veitz.

On the other hand beam axle designing of rear suspension has obtained some enough compliance to make the driver feel like in the more upper class automobile, just it's illusion.

Anyway most of B and C segment F/F automobiles has torsion beam rear axle design, I do not always agree this tendency, because I miss steering astringency so much.