Speedtech Subframe?

[Norm Peterson]

From a kinematic standpoint, I could see this popping up as deflection in the tie rods lunder load leading to some strange behavior. Wasn't that why GM moved to front steer on 2nd gens? Of course that's recirculating ball vs. rack and pinion, but the basic physics behind the two should be the same, if perhaps to different extents.

It's not really about tierod deflection, and possibly not about resistance to buckling either. I suspect that in most cases developing the tierod buckling load would yank the steering wheel out of your hands.

The move to front steer allows the use of softer control arm bushings, because the compliance steer then becomes an understeer effect rather than oversteer. Basically, you want the cornering load to induce the outboard wheel to steer slightly out of the turn rather than more tightly into it, which requires whichever component is in front - steering linkage or control arm(s) - to have the stiffer mounting.

A rear steer car really needs to either be using rather firm control arm bushings, or relatively soft rack mounting bushings, or possibly both (particularly with the sort of tires available now vs back in the early/mid 1960's). Most FWD cars are rear steer by necessity, and the rack mounting is soft enough that the whole rack visibly moves laterally when the steering wheel is turned with the car stopped and the full car weight is resting on just the tires.




Norm