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I see that you have standard track control arms that must use the standard inner pivot positions. The general princples behind getting zero bumpsteer is for the rack track rod to describe the same arc as the suspension so that the axle does not need to pivot as it goes through the suspension movement - if it does then that is bump steer. With a simple geometry like the 1302/1303 super if the pivot for the trackrod is at the same distance from the axle as the track control arm AND it is parallel to the track control arm in the mid turn position then I would expect minimal (if any) bumpsteer.
The rack you are using has the pivots well outboard of the inner suspension pivot so that the track control arm and the trackrod will describe different arcs thus pulling the outer steering arm in as you pass the static pisition on both bump and droop.
The best VW racks are the Polo and early Passat that have central style pivots for the trackrod that make it very adaptable for different inner pivot positions.
The other thing to be aware of when locating a rack is the effect of the fore and aft position of the rack on the ackermann steering. You ought to be aware that the inner front wheel describes a tighter radius than the outer wheel in a turn (ackermann steering). This is effected by the position of the rack and the steering arm angle at the axle end. IIRC moving the rack forward of the parallel position locates the instantaneous centre forward of the rear axle and behind the parallel position puts that centre behind the axle. For true ackermann steering the instantaneous centre should be in the centre of the rear axle. I realise that most circuit racing designers are not overly bothered about ackermann steering and the current trend in F1 is for parallel steering but it ought to be recognised that circuit racing demands small steering angles and front end scrub can be desireable to put heat into lightly loaded front tyres. That is not the case for a road car or one that is used for autotesting/autosolo/slalom.
Clive
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