In the paper the main directions of the development of the methods for designing selected geometrical features of the mechanical components along with its representation in technical drawing were described. The influence of the shape deviations on the condition of the mechanical connections and its fits was defined and characterized. It was proved, that the shape obtained in the machining process significantly differs from the nominal shape of the designed parts. The consequence of the following deviations are the troubles during cooperation of the parts, which perform either rotary or reciprocating motion. The results presented in this paper contain the measurement of the real geometry of the journal and the hub along with determination of the value and the type of their shape deviations. Authors have proved that the magnitude of the shape deviations are subject to the errors connected with the methods of measurement and used tools. Proper simulations were performed, which shows the certain influence of the shape deviations on the cooperation of the mechanical parts considering both static and dynamic loading.