Abstract: An improvement in a disc brake assembly is provided. The assembly includes: a rotatable disc; a caliper; an anchor frame for securing the said disposition of the caliper; a keyway between the caliper and an adjacent surface of the anchor frame; a key disposed in the keyway for providing lateral sliding movement between the caliper and the key; and a caliper support spring between the key and the caliper for supporting the caliper on the key. In the improvement, the key has a surface hardness of at least 62 and is configured such that the full compression force of the support spring is at least 6 g's and less than 9 g's and the effective sliding friction between the caliper and the key is decreased. With this improvement accumulated rust between the key and the caliper sliding surfaces is reduced and the caliper is more freely slideable on the key. The key is made of, or coated with, a non-corrosive material.