Abstract: An automotive seat assembly including a seat frame having a main portion fixedly mounted to the bottom of a vehicle seat and a riser portion fixedly mounted to the floor pan of a vehicle. A seat drive mechanism is included having at least one drive motor and a threaded lead screw. A drive nut having a through-bore with internal threads that cooperate with the threads of the lead screw is adapted to cause the seat assembly to move relative to the vehicle floor pan in response to the drive motor. The drive nut also includes a second bore formed adjacent to, and extending in the general direction of, the through-bore such that the internal threads of the through-bore are interrupted by the second bore and act to clear the threads of the lead screw and prevent foreign matter that collects on the lead screw from entering the threaded interface between the drive nut and the lead screw.