Nude TT / Armpod question

Have done reading on here lately about the benefits
of separating the armpod completely from the platter
plinth.

This seems good in isolating motor vibrations from the
arm/cart assembly, if that is the design purpose.

I may have missed this in reading all the posts, but
with a separate armpod structure, how do you maintain
the strict distance relationship between the arm pivot
and the spindle center ? The armpod can now move
(semi-)freely.