Brake rotor? What is that? We never had the luxury of disc brakes back then. The 47 had the Frankland hubs with the Buick style Drums/Shoes as did Tommy's 7JR back in the day.......lol. I remember the first time that I had the opportunity to drive a car with disc brakes and thinking "man no wonder those guys run so good". The drum brakes kind of slowed the car down some but the disks actually "stopped" it!!