A rotor shaft cap for a gas turbine has a disk-shaped body defining a first axial face, a second axial face, and an outer radial face. The disk-shaped body has a first annular jaw provided on the first axial face. The first annular jaw includes a plurality of teeth projecting from the first axial face. A plurality of apertures are defined by the disk-shaped body, each aperture of the plurality of apertures extends through the disk-shaped body along an axial direction.