A propulsion assembly for a rotorcraft includes a mast including a distal ridge and a proximal ridge forming a retaining pocket therebetween, a raceway receivable by the retaining pocket to form a press fit between the mast and the raceway and a mast bearing assembly including a plurality of bearings facing the mast to engage the raceway. The distal and proximal ridges are operable to reduce axial motion of the raceway along the mast, thereby securing the raceway in the retaining pocket.