Identification of natural frequencies is a fundamental step in crankshaft design. For satisfactory operation they should be well separated from the operating speed range and several of its harmonics. These frequencies depend on crankshaft's mounting conditions, its geometry and material properties. In this work ten crankshaft parameters are identified besides the bearing stiffness which can bring about changes in natural frequencies. The effect of variation of each of these parameters is studied. Also, the feasibility of using geometrically identical spheroidal graphite iron crankshaft in place of a forged one is examined from the point of view of natural frequencies. Three crankshafts are considered for the intended study.