In view of
Alex's and
steddie eddie's replies I took a look
at a few images from Smart and there
may be a way to get
to remove the broken stud as well as fit a new stud without
any cutting of the backplate at all !
In the image below it appears there should be enough room
after one has removed the brake caliper...as it looks like there
will be enough room to 'slip by' the side of the hub unit.
(red arrow shows possible path to take to insert the new stud)If this works, then the new stud being an
interference fit would have
to be 'drawn'/pulled all the way into the hub flange. The simplest
method to do that is to temporarily refit the wheel, and the wheel nut
on the new stud is then tightened to pull the stud into place. Once
that is done, remove the nut/s and wheel, refit the brake caliper, and
then finally refit the wheel and torque the wheel nuts up.