The friction disk material was usually a wooden disk between the two faces of the steel arms. As for the development of the clutch and brake shoes, the development of these friction materials was in its infancy. Treated leather had been used for clutches and although it offered good friction behaviour, it was prone to stiction when first moving off and also failed when overheated. Asbestos-based friction materials were sometimes used for racing, in an attempt to keep dampers working correctly even when overheating.
