Abstract: An annular carbon brake disk having cast metal keyslot reinforcement members which are shaped to intimately conform to the contour of the keyslots and to an adjacent surface area of the disk on each side of the keyslots. The reinforcement members are preferably investment castings of heat resistant stainless steel or other suitable metal and the walls of the reinforcement members are substantially thicker at the portion contacting the keyslot than at the other portions of the members. The keyslot reinforcement members may be used with either continuous or segmented disks.