1963 NASCAR International Rule Book Specifications NASCAR Grand National Championship Circuit Section 20-3 -- Brakes and Hub Assembly

a. Any interchangeable brake and drum assembly may be used. Dual master brake cylinders are recommended. No spot or disk brakes allowed. Wheel treads must conform to NASCAR specifications for make and model. (See supplement.)

b. Backing plates and drums may be drilled for better air circulation but no scoops, fans or other attachments will be permitted.