Improvements in disc brake friction and wear characteristics are usually sought by alternating the disc pad composition or processing conditions. This study investigated the effects of varying the cast iron rotor chemistry and microstructure on the performance and wear resistance of a disc brake composed of such rotors and standard commercial semi-metallic disc pads. A statistical design of an engineering experiment was used to determine such effects of five chemical variables of the cast iron rotor -- C, Si, Mn, P and Ti -- and two processing variables -- solidification and cooling rates. An increase in manganese or phosphorus content improved brake performance and decreased pad wear, compared to a standard chemistry cast iron. Cast irons with high titanium or carbon levels showed low friction and high pad wear. Improved performance but high pad wear were found for cast irons with high silicon contents. A fast liquid solidification rate or a fast solid cooling rate significantly reduced pad wear without influencing performance. The changes in rotor chemistry in the present study did not seem to affect the rotor wear, however.