A method of manufacturing a crankshaft comprising providing two parts, each part comprising two webs, a portion of a crank journal and a portion of a main journal, welding the two portions of the crank journal together, heating the crank journal, inserting a shim between the webs, and upset forging to reduce the length of the crank journal to form a forged segment. Alternatively, the portions of the main journal may be welded, heated, shimmed, and forged to form a forged segment. The crankshaft may be lengthened by adding additional parts or forged segments using the same steps. A production line for carrying out this method when producing a crankshaft with n number of crank journals, where n is an even integer.