KA24DEvelopment.com :: 240SX Brake Upgrades
some more stuff more specific.
the almighty Asad used to have a good writeup with pics to differentiate iron/aluminum and measurements from 26 to 30mm z calipers but i think it's gone now.
also big note: i run 26mm z calipers...if u plan on wanting z calipers AND some aftermarket slotted or drilled rotors, get 30mm Z calipers. reason being the 26mm calipers were only produced for 6 months during the first year of the nonturbo Z32, so being such a little production range, aftermarket rotors for 26mm calipers are very expensive, as in instead of $140 for a set of powerslots, its $140 per rotor for 26mm. just a heads up, i found out the hard way, but stock blanks on an S chassis are fine with proper pads and lines. i only get fade on z front/stock rear setup after 10-15 minutes of hard road racing, which isnt good but for the street you wont ever fade like that unless you're beating the shit out of it.