Originally Posted by Deuce
TRUE ,,, I was thinking about my reply ... and came back to change it to BUMP STEER ... and had already been caught with incorrect information.
MARTINSR is correct.
Mounting the rack on the crossmember or the axle is still a bad idea IMHO.
It's not a bad idea, it's a HORRIBLE idea. The arch of the pivot points simply aren't going to match those same points on the axle. ONE of them is going to change during movement and you will have bump steer. But the same thing can happen with that Vega box mount, it makes no difference if the rack was mounted to the crossmember or the frame two inches behind or hanging off the frame on that Vega box adapter. The exact same issue exists, are the pivot points on the inner and outer tie rods going to follow the same arch (thus staying the same distance apart) as those same points in the arch of the axle?
The design you are using may be a "rack and pinion" by the design of unit it's self but the way it's mounted it really isn't a "rack and pinion" as we know it, it's simply a cross link "steering box" of a different design.
If it were mounted like that without a tie rod running from left to right spindle and you had the tie rod ends going off the rack to the left and right spindles you would have the exact same issue as if it were mounted to the crossmember. Just to clear things up your "rack and pinion" in your setup is actually a simply replacing a steering box and drag link.