[JSeery]

The shape of the steering rod (drag link) should not be a factor, the steering arm has no idea what shape the drag link is. It is the relative position of the pitman arm end and the steering arm end that is important and that would be determined by a straight line between them. The big factor in bump steer is the relative position of the radius rod end and the pitman arm end, if the drag link rotates in a different arc than the radius rod it can push or pull the steering arm as the wheel move up and down. This can be because of the angle between a line between the pitman end and the steering arm end and the radius rods or the length of the drag link and the radius rods.