The invention relates to a toothed wheel (116) for a gear motor (10) of a window wiper, in particular of a motor vehicle, this wheel having a central member (120, 128) defining an axis of rotation A and two opposite substantially parallel faces, a first of said faces including an orifice (124) having an axis B and intended to receive a pin (26) of a linkage (38) of the gear motor, characterized in that it comprises, on said first face, abutment means (128a, 154a) in an axial direction and/or in a radial direction relative to axis A and means (128a, 154a, 152a) for guiding sliding in a circumferential direction about the axis A, said abutment and guide means being configured to cooperate with said pin during the assembly of the toothed wheel with the linkage in order to facilitate the insertion of the pin into the orifice.