L18_B110 wrote:
get's a bit confused talking about roll centres and roll steer all at once like that. But assuming you're mainly talking about roll centres and roll axis - all roll centres are dynamic things, they never stay in one location (height) in any production suspension configuration. Sliders are probably worse than hangers for maintaining roll centre height because they fix the roll centre to the body. As the body leans while cornering and gets closer to the ground, so does the roll centre The roll centre height changes exactly witht he height of the body at that side. With a shackle as the body leans, the spring compresses and (typically) lengthens, pivoting the rear hanger back and upward, giving back some of the lost roll centre height. But changing shackle angles also change spring rate... And that is the main advantage of sliders - consistent spring rate.

If you're worried about changes in roll axis during cornering, the strut front end is going to be the main player - they have notoriously poor dynamic control of roll centres.

On the idea of front and rear eyes at the same height - leaf spring setups always handle best with the rear eye higher. And it wouldn't stop twist anyway - any time there is roll, the twisting of the live axle has to cause leaf spring twist. Its just inevitable.