Today I looked at an original 2005 Roadster and the difference in the front suspension is obvious. If you look at the centre of the steering rack, on current models the track rods (the long bars which connect to the stub axles) are horizontal at rest. The 2005 spec has track rods which are angled upwards in a shallow V shape.This is quite distinctive, and can cause nervous, and some might say 'twitchy' steering. When a front wheel is deflected upwards, because the track rod is already angled upwards, the additional upward arc of the track rod shortens it's horizontal length. The effect of this is that the stub axle, and wheel 'toes in' slightly. So the car will tend to move away from the side under compression. If the other side lifts, so the suspension droops, then the effective length of the trackrod increases, which causes toe-out, and this will exacerbate the 'twitch' away from the "bump in the road". So an uneven road generates bump steer. The effect on corners where roll is present (not so much of an issue for Mogs), the effect is the same in that the car will tuck in due to the outside wheel on bump toeing in and the inner wheel on rebound toeing out.
Current cars have the ideal arrangement whereby the track rods are horizontal at rest. So movement either on compression or rebound is away from the position of maximum length - which means that each stub axle will toe in slightly either way. So no bump steer............
