Great. I think the remaining 'bump steer' may actually be due to the offset of the geometry, or incorrect king pin inclination. To put it another way, the upright is too upright and if a line is drawn down through the angle of the upright to the ground, instead of the line more or less being in the centre of the tyre, it will hit the ground a good couple of inches, around 500mm, inside the tyre, this will inevitably give some kickback due to the leverage. Does that make sense?