Method for assembling on a bottom plate comprising a housing extending along a first housing axis, said housing being surrounded on at least one face of said bottom plate by a first bearing surface about said first axis, on the one hand, a pivoting timepiece wheel set including a drive surface in proximity to a rear axial end, and on the other hand, at least one spacer for receiving in position and guiding the pivoting of said wheel set relative to a said bottom plate, said spacer including a surface arranged to cooperate with said housing with a first constriction value or in a fixed hold via rivets or welding or adhesive bonding, said spacer further including, on a collar, a second bearing stop surface arranged to abut against said first bearing surface of said plate, and said spacer further including a front end face at an opposite end to said second bearing stop surface relative to said collar, characterized in that: - said wheel set is made with a collar located in proximity to a front axial end, opposite to said rear axial end, said collar of said wheel set comprising a wheel set reference surface located, on the side facing said rear axial end, in proximity to said front axial end, said wheel set further including, at said front axial end located on the other side of said collar relative to said drive surface, a machined portion arranged to cooperate with a second constriction value with a complementary machined portion comprised in a display element to fixedly secure said element to said wheel set; - said wheel set is inserted in said spacer, so as to bring said wheel set reference surface opposite to said front end face; - a drive means is fixed, by driving in, welding, adhesive bonding, rivets or laser fusion, to said drive surface of said wheel set, so as to position a bearing surface of said drive means at a distance from said wheel set reference surface which is set either by adjustment or by the abutment of said drive means on a surface, if said wheel set has one, in order to stop said drive means, and a certain wheel set endshake is set around said spacer for the sub-assembly formed of said spacer and said drive means, - the pre-assembled sub-assembly formed of said wheel set, said spacer and said drive means is inserted into said housing, with said second bearing stop surface of said spacer abutting against said first bearing surface of said bottom plate, said surface cooperating with said housing with a first constriction value or in a fixed hold via rivets or welding or adhesive bonding; - said display element is driven in and secured by causing said complementary machined portion to cooperate with said machined portion for the secure attachment of said display element to said wheel set, with a second constriction value. - said wheel set is made with a collar located in proximity to a front axial end, opposite to said rear axial end, said collar of said wheel set comprising a wheel set reference surface located, on the side facing said rear axial end, in proximity to said front axial end, said wheel set further including, at said front axial end located on the other side of said collar relative to said drive surface, a machined portion arranged to cooperate with a second constriction value with a complementary machined portion comprised in a display element to fixedly secure said element to said wheel set; - said wheel set is inserted in said spacer, so as to bring said wheel set reference surface opposite to said front end face; - a drive means is fixed, by driving in, welding, adhesive bonding, rivets or laser fusion, to said drive surface of said wheel set, so as to position a bearing surface of said drive means at a distance from said wheel set reference surface which is set either by adjustment or by the abutment of said drive means on a surface, if said wheel set has one, in order to stop said drive means, and a certain wheel set endshake is set around said spacer for the sub-assembly formed of said spacer and said drive means, - the pre-assembled sub-assembly formed of said wheel set, said spacer and said drive means is inserted into said housing, with said second bearing stop surface of said spacer abutting against said first bearing surface of said bottom plate, said surface cooperating with said housing with a first constriction value or in a fixed hold via rivets or welding or adhesive bonding; - said display element is driven in and secured by causing said complementary machined portion to cooperate with said machined portion for the secure attachment of said display element to said wheel set, with a second constriction value.