Support case for a steering column

The support has a base forming part mounted on an edge of a passage hole (34) of a steering column, and a sleeve forming part including an end (24) pierced by an opening (28). The former part has a metallic non-deformable ring (16). The latter part that surmounts the non-deformable ring has a plastic rigid portion (18). The non-deformable ring and the rigid portion form a single monoblock portion. An independent claim is also included for a method for mounting a steering assembly.