The paper describes the mathematical model for C axis of the multifunction turning center with worm gear. Talks about the mathematical model with multi-body mass dynamic system. The drive works in the positional feedback and his mathematical model is specified for detection of the dynamical behaviors of the C axis. The turning center is designed for a heavy roughing forged piece from high carbon steels by the power of main motor 71kW. The C axis must be designed as accurate angle position axis and with big dynamic stability of regulation by step or pulse loading. The C axis drive is constructed with help of a hydraulic connected up the worm gearing on a spindle. The driven side of the worm gear is created two dual worms with own servomotors. Worm wheel is solved as one part with two gears. Servomotors are controlled with the mode speed/torque coupling (MASTER-SLAVE), which guarantees the constant torque prestressing between the servomotors. The difference of a torques guarantees leaning of both worm teeth on opposite tooth faces of both gears of the worm wheel. In the dynamic model are involved the friction on the worm gears, torsion stiffness located with help of the FEM and moment of inertia for all parts. 3D models of the C axis is designed in the program ProEngineer. From complete 3D model of the C axis are transfered individual parts to the FEM in surroundings Ansys as volume parts. In this paper is main output influence of the diference between the 3D and 2D for calculation of the stiffness in the contact of the worm gear on the whole dynamic system of the C axis. The value of the torsion stiffness by more situation of the load on the worm gear is used subsequently to the multi-body mass system of the C axis drive and to the eigen frequencies analyses. Results of this paper will be sensitivity check of the changing torsion stiffness on the worm gear by the loading changing on the resulted position accuracy on the C axis. Next review is, if the control modul MASTER-SLAVE is partially this problem of the difference between values of stiffness from 2D or 3D model or also stiffness non-linearity eliminated.