The problem of gear eccentricity is more and more often considered and developed in simulation models. Eccentricity is unavoidable due to finite manufacturing accuracy and assembly process and thus can only be minimised. Eccentricity can have a significant impact on dynamics primarily due to its effect on gear stiffness and teeth position. Previous models of gear eccentricity have dealt with parallel axes. When considering the problem of eccentricity with non-parallel axes of symmetry and rotation, one must take into account new phenomena that occur. For a case of eccentricity with non-parallel axes, such phenomenon is the axial displacement of gear teeth, the occurrence of which generates a friction force along the axis of rotation of the gear. The main objective of this study is therefore to develop a model that would take the axial movement of gear teeth into account. To this end, the kinematic parameters of this movement, including displacement, velocity and acceleration, are determined in a selected plane. The developed models should contribute to increased accuracy of modelling gear operation and occurring phenomena. Analysing teeth friction in occurrence of eccentricity with non-parallel axes must include axial movement of teeth to receive accurate results. In the case of helical gears the influence on dynamic behaviour is even greater because of direct influence of position of contact point.