A camshaft of an automotive engine includes two concentric contra-rotating shafts mounted one inside the other, namely an inside shaft and an outside shaft, at least one cam rotatably mounted on the outside shaft, fixedly connected to the inside shaft radially through the outside shaft via a fastening mechanism, a sleeve gripped by the fastening mechanism and inserted fixedly into aligned boreholes in the inside shaft and in the cam, a core that widens the material of the sleeve within its elasticity limits in the area of the inside shaft and is inserted into the sleeve after insertion of the sleeve into the shaft mechanism. To improve mountability, the core extends over the entire length of the sleeve and widens it beyond the area limited by the inside shaft without exceeding the upper limit of elasticity of the material of the sleeve in comparison with its uninstalled starting state.