Information On Machining Grey Cast-Iron Brake Discs

Possible complaints 

• Damage due to lack of use (rusting). This causes vibrations in the steering wheel, noises and brake pedal pulsation.
• Brake disc becomes distorted as a result of serious driving, e.g. on a racing circuit.
• Too much lateral runout when new brake discs are fitted on dirty or distorted wheel hubs.

Procedure 

• Check brake disc for cracks, minimum thickness, lateral runout, thickness tolerance, flatness and surface roughness.
• If necessary, (depending on the actual brake disc thickness and the brake disc wear limit) machine the brake disc using one of the disc brake dressing machines approved by Porsche.
• The brake disc must only be reworked symmetrically, i.e. equally from both sides! Observe the operating instructions for the disc brake dressing machine!