The crankshaft of a piston engine is assembled with a vibration damper into a discrete module prior to mounting of such module in axial and/or radial bearings of the housing of the engine. The damper has an input element which rotates with the camshaft and a mass which is angularly movable relative to the input element against the resistance of coil springs. The input element can be provided with a sleeve which surrounds a snout at one axial end of the crankshaft. Alternatively, the damper can be installed in or on or can constitute a cheek of the crankshaft. The coil springs can operate in parallel with a friction generating device which also opposes rotation of the input element and the mass of the damper relative to each other.