I'm having trouble with this one, I confess...

For example, in what kind of application could a spherical bearing provide motion that wasn't already allowed by flexion of the OE material?

We had this conversation here a few years back and, after the dust settled, I admit that i had got to the point where I couldn't find a bright line anywhere between "must be stock" and "spherical bearings," looking just at the logic and attributes of the parts involved.

If you can change the material, it's - as far as i can tell - necessary that changes in dimensions be allowed, too. Am I wrong?

Short of writing a dissertation about the different types of bushing (there are two different ones in each of my Golf A-arms), and what can and cannot be changed, how would the interpretive distinction be made, to allow dimensional differences, multi-material options (e.g, urethane-only vs. rubber-on-metal), or design differences short of "spherical-ness" without crossing the line?

K

EDIT - the GCR glossary def of "bushing" is also problematic. The rear "bushing" on my A-arms is a rubber donut, with a steel sleeve in the middle, and a metal ring around the periphery. It presses into the arm, and a bolt goes vertically through its middle, through the subframe and into the chassis. By the strict definition, it's NOT a bushing, becuase the absolutely necessary flexion of the part is a "purpose" beyond that described by the definition ("to reduce the dimension(s) of an existing hole") - so I can't change it? Is that the intent?