This bulletin applies to 2014 to present Porsche 911 Turbo/Turbo S vehicles. Some customers have reported a clicking noise at slow speeds.
Due to tolerances on some of the parts connecting the brake disc to the mounting plate, small relative movements between these parts can occur. As a result, a clicking noise can be heard when the brakes are applied at low speeds.
The 911-II rotors have a slightly different design for the attachment of the rotor hat to the disc, starting with model year 2017. These rotors are retro-fittable on the 991 generation I vehicles.
Before rotors are replaced, it is necessary to check the mating surfaces of the wheels with a straight edge (12-inch Starrett 380) to ensure flatness of the surface. Imperfections in the surface may have an influence on the rotor and can cause noise. It is necessary to check for flatness in about 6 different positions around the mating surface (roughly every 60 degrees).
The mating surfaces at the outer and inner areas of the mounting circle need to be checked for flatness. The recessed area in-between is not part of the measurement. Use a feeler gauge that is very thin. The .05 mm thickness is probably going to be necessary to find the uneven areas. Record all measurements.
Ensure that the center locking wheel bolt is properly lubricated in accordance to workshop manual 440519. Ensure that all mating surfaces are clean and free of debris. When torqueing the wheel bolts, make sure that the vehicle is off the ground. Use a torque wrench in one sweeping motion, not an intermittent jerky motion.
The new rotor part numbers are listed here (911-II rotors)
Front left........... 991.351.407.06
Front right......... 991.351.408.06
Rear left........... 991.352.409.07