[gerryb]

I'm a bit confused with this thread. This is what I have 'seen' with Z31's.

MkI 84 to late 86 - non ventilated disc on rear 290mm dia. same calipers as s12 with the exception of mounting 'ears' which are longer to accomodate 290mm dia. rotor. (NB non turbo = 4 stud till 85, all others 5 stud)


MkII early 87 to 88 ventilated rear rotors,(both turbo and non turbo are all 5 stud) can't remember exact diameter, 282mm from memory. Calipers match rotors with wider opening to suit, (not interchangeable with earlier calipers). The trailing arms have a 10mm longer "bearing tube", to push the hubs out 10mm to suit the extra 10mm of rotor width. (I have a set of these later trailing arms complete and have compared it physically and measured the differences with earlier type Z31 setup)

So in closing if you want the ventilated setup you need the whole trailing arm with rotors and calipers and swap it onto your s12.