Hub cap vent device

A vehicle hub cap comprising, in combination, a hub cap body having side and endwall portions, a fastening portion adapted to cooperate with a portion of a rotary vehicle hub, and a breather vent assembly, said breather vent assembly comprising, in combination, a breather vent disc and a breather vent disc carrier positioned within said cap body end wall and having a center vent opening in which said disc is secured in mechanically snug relation, said disc being made from fine particles of a non-metallic material, with portions of the exterior surfaces of said particles being fused to one another so as to leave plural breathing passages between said particles, said passages providing a porosity such that, when clean, a disc of said material having an exposed diameter of about 0.15 square inches will permit air to flow therethrough at from about 800 cc to about 5,000 cc per minute at 1 psi, and when coated with grease, said disc will permit at least 80-100 cc's of air per minute at 1 psi to pass therethrough.