Girodisc Chevrolet Camaro ZL1 (6th Gen) Front RotorsThe Girodisc system is a direct replacement for the OE disc however a different brake pad with an annulus (pad swept area) of 66mm or less must be used. This is done to bring the weight of the disc down a bit. The OEM rotor utilizes a pillar vane design which is horribly inefficient and heat soaks very easily with no way of effectively dissipating that heat so Chevrolet took the easy route and made the rotor extremely heavy to combat the heat. We