A hinge assembly for mounting a toilet seat to a toilet bowl, the hinge assembly comprising: a hinge post defining an opening and including an upper surface that surrounds the opening; a threaded fastener extending through the opening of the hinge post and configured to extend into a bore in the toilet bowl, the threaded fastener having a first end portion and a second end portion; an adaptor having a first segment coupled to the first end portion of the threaded fastener, a second segment, and a shear segment connecting the first and second segments (118, 696), the first and second segments (118, 696) both configured to be engaged by a tool to rotate the threaded fastener, the shear segment having a lower torque resistance than the first and second segments (118, 696) such that the shear segment breaks when a torque applied to the second segment reaches a predetermined amount; a bushing positioned around a portion of the threaded fastener, the bushing having a flange and a lower section configured to extend into the bore in the toilet bowl, the flange supported by the upper surface of the hinge post over the opening, the lower section having an outer diameter that is smaller than the opening in the hinge post such that the hinge post is movable relative to the threaded fastener and the bushing to adjust a position of the hinge post on the toilet bowl; and further comprising a nut threadably coupled to the second end portion of the threaded fastener, the nut including an expandable upper section configured to extend into the bore in the toilet bowl; wherein the nut has a surface that is engaged by a surface of the bushing so that the expandable section of the nut expands as the nut moves relative to the threaded fastener to secure the hinge post to the toilet bowl; and wherein the nut is generally cylindrical and has an outer diameter that, before the expandable section is expanded, is smaller than the opening in the hinge post such that the nut is insertable through the opening with the threaded fastener and the bushing. a hinge post defining an opening and including an upper surface that surrounds the opening; a threaded fastener extending through the opening of the hinge post and configured to extend into a bore in the toilet bowl, the threaded fastener having a first end portion and a second end portion; an adaptor having a first segment coupled to the first end portion of the threaded fastener, a second segment, and a shear segment connecting the first and second segments (118, 696), the first and second segments (118, 696) both configured to be engaged by a tool to rotate the threaded fastener, the shear segment having a lower torque resistance than the first and second segments (118, 696) such that the shear segment breaks when a torque applied to the second segment reaches a predetermined amount; a bushing positioned around a portion of the threaded fastener, the bushing having a flange and a lower section configured to extend into the bore in the toilet bowl, the flange supported by the upper surface of the hinge post over the opening, the lower section having an outer diameter that is smaller than the opening in the hinge post such that the hinge post is movable relative to the threaded fastener and the bushing to adjust a position of the hinge post on the toilet bowl; and further comprising a nut threadably coupled to the second end portion of the threaded fastener, the nut including an expandable upper section configured to extend into the bore in the toilet bowl; wherein the nut has a surface that is engaged by a surface of the bushing so that the expandable section of the nut expands as the nut moves relative to the threaded fastener to secure the hinge post to the toilet bowl; and wherein the nut is generally cylindrical and has an outer diameter that, before the expandable section is expanded, is smaller than the opening in the hinge post such that the nut is insertable through the opening with the threaded fastener and the bushing.