122-R7L3B-09

USA
Advanced Technical Information
1503
4651
4
Clicking Noise From Front PCCB Rotors
Revision:		
This bulletin replaces bulletin Group 4, #1503, dated May 10, 2017.
			“of the braking system.” was added to the end of the first note under Information. New note was
added to page 3.
Vehicle Type: 		
911 Turbo / Turbo S (991)
Model Year: 		
2014 to present
Information:
PCCB Rotors may be making a clicking type noise.
			NOTE: The clicking noise in no way impairs the performance or safety of the braking system. The
			customer may continue to drive the vehicle without restriction. The clicking noise does not constitute a defect.
			NOTE: Due to the customer sensitivity of this issue, please submit a TLAR from the beginning of
the issue.
			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 991-II rotors have a slightly different design for the attachment of the rotor hat to the disc
(Starting in MY 2017). These rotors are retrofittable on the 991 generation I vehicles.
			
Pre Checks
			Wheels - Before rotors are replaced, it is necessary to check the mating surface of the wheels with
a straight edge (12” Starrett 380) to insure flatness of the surface. Imperfections in the surface
may have an influence on the rotor and cause noise.
AfterSales
August 1, 2019
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USA
Advanced Technical Information
1503
4651
Information
(continued):		It is necessary to check for flatness in about 6 different positions around the mating surface
(roughly every 60°), it is ok to do more than that, but not less.
			The mating surfaces at the outer and inner areas of the mounting circle need to be checked for
flatness. The recessed area in between (photo below) is not a part of the measurement.
Measure here
Not here
			Use a feeler gauge that is very thin. The .05mm thickness is probably going to be necessary to find
the uneven areas.
			
Record all measurements; make sure to include photos in PQIS.
AfterSales
August 1, 2019
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USA
Advanced Technical Information
Information
(continued):		
1503
4651
4
Center locking wheel bolt - Insure that the center locking wheel bolt is properly lubricated in accordance with WM 440519.
Insure that all mating surfaces are clean and free of debris.
 hen torquing the wheel bolts, make sure the vehicle is off the ground. Use a torque wrench (that
W
is properly calibrated) in one sweeping motion, not an intermittent jerky motion.
			NOTE: If the noise persists after verifying proper torque and flatness of the wheel, the wheel
bearing, lower control arm, or trailing arm connections, may be the cause of the noise. Replace the
wheel only as a last resort.
Rotors – The new rotor part numbers are listed below. They are also in PET.
991- II rotor part numbers:
Front Left Rotor: 991.351.407.06
Front Right Rotor: 991.351.408.06
Rear Left Rotor: 991.352.409.07
Rear Right Rotor: 991.352.410.07
NOTE:
			
Due to small design changes, 991- II rotors may not be an identical visual match to 991- I
rotors. This is considered normal and does not constitute a defect in workmanship or justify replacement.
Reference:
465119 Removing and installing front PCCB brake disc.
Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training courses. They are
written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special tools may be necessary in
order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the safe operation of your vehicle, and
may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and safely. Part numbers listed in these bulletins
are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a discrepancy, the work procedures in the PIWIS Tester
are the ones that must be followed.
©2019 Porsche Cars North America, Inc.
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August 1, 2019
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