it's a disc/drum; it is more like a disc. I tried hammering the part where it is attached to the hub with a regular hammer as well.

__________________
1983 560SL Megasquirted (originally 380SL)

My former Mercedes:
1985 300SD ~190k
1990 560SEL
2000 C220 CDI
1983 380SEC 102k dual-chain conversion
2000 C280 70k (sold)
1987 300DT (W124 - sold)
1972 220D (sold)
1971 220D (sold)