New motor direct coupling question

I'm working on changing a Bridgeport from a NC to a CNC unit. The
NEMA 42 motors are directly coupled to the screws, but the have what
looks like neopreen bushings around the mounting screws going through
the mounting brackets giving some smll ability for the motor to have
some give. Has anyone seen this arrangment before? Should I change
the setup to flexible shaft couplings? I've got some off another
machine which look like rubber gears that go around a finned metal
disk on each side. Are these OK (if you think the original mounting
is inappropriate).

Thanks and regards,
Jeff