Non asbestos frictional material is also a lot harder on drums. I still have a drum lathe that will handle 16 1/2 by 7 truck drums, but we don't hardly use it any more. The pads we use now get the drums so hot that they have hot spots that won't cut. There is about 1/4" on the lip of the drum that doesn't contact the pads. We cut the ridge out so the drums look new. DOT inspectors think the pads are out of spec if they can't see them. We have a grinder on our lathe, and occasionally we use it to dress the hot spots. I started driving a 1950 GMC to school in 1958 and I tell people we didn't need power brakes in those days. We had asbestos.