The present application relates to a system for creating a dynamic seal of a hydrostatic motor (M) which is intended to be mounted on a shaft (1), said system being characterized in that it comprises: a sealing element comprising a carrier (3) and a dynamic sealing means (4), said carrier (3) being provided with a centering surface (37) for centering with respect to a shaft (1), centering means (7) for centering said sealing element with respect to said shaft (1), fixing means (6) for fixing said carrier (3) to a planar bearing surface in a position defined by said centering means (7), said centering means (7) being designed for mounting said floating sealing element on said planar bearing surface with respect to the shaft (1) before it is fixed to said planar bearing surface.