Description of defect: Disc shows colouring of varying intensity and shades (blue, violet, golden), mainly visible in the cooling areas (groove and carrier interior).

Consequences: Initial slight vibrations that progressively increase. Overheating of this type alters the mechanical characteristics of the cast iron in as much as there is a change in structure due to the formation of cementite (Fe3C).

Advice: Always advise users to observe a running in period. Brake only moderately and briefly during the first 200-300 kilometres over a mixed itinerary. Avoid prolonged pad to disc contact.

Description of defect: Disc thickness is considerably less than the recommended minimum thickness (4 mm less in total). Cracks are evident. Heat spots are visible in areas corresponding to the ventilation blades. This is advance warning that other cracks will form.

Consequences: Noises, vibrations.

Advice: This situation is typical of that found on certain sports vehicles which are subjected to an intensive and excessive use on the road.