SIB340921

2/27/23, 3:50 PM
34 09 21_TURBINE TYPE NOISE DURING DECELERATION: AUDIBLE FROM THE REAR AXLE
SIB 34 09 21
2023-02-14
TURBINE TYPE NOISE DURING DECELERATION: AUDIBLE FROM THE
REAR AXLE
This Service Information Bulletin (Revision 1) replaces SI B34 09 21 dated September 2021.
What’s New:
Model G87 M2 Coupe added
MODEL
F80 (M3 Sedan)
F82 (M4 Coupe)
F83 (M4 Convertible)
G80 (M3 Sedan)
All with standard MCompound brake
rotors
G82 (M4 Coupe)
G83 (M4 Convertible)
F87 2016 to 2018:
(M2 Coupe).
2019, 2020: M2
Competition Coupe
G87 (M2 Coupe)
SITUATION
A turbine-like noise can be heard from the rear axle while deceleration during the first 300 miles of operation
when braking from low speed. See attached video V34 02 21.
CAUSE
The noise is triggered by the pairing of brake pad/brake disc cross-grinding in the rear-wheel brakes that is
unique to the M-specific vehicles listed above.
The cross-grinding is absolutely necessary to ensure that friction builds up as quickly as possible and
supports a uniform wear pattern.
CORRECTION
After approx. 300 miles, the running-in phase (cross-grinding elimination) has finished and the noise can no
longer be heard.
This is a normal running-in operation of the brake system and part replacements for this issue is not
required.
Note: If new brake discs are installed at a later point in time, a new running-in phase (cross-grinding
elimination) of approximately 300 miles will be needed.
QUESTIONS REGARDING THIS BULLETIN
Technical inquiries
Warranty inquiries
Parts inquiries
Submit feedback at the top of this bulletin
Please contact the Warranty department by either using the Live Chat that’s
available in the Warranty Documentation Portal or through IDS by selecting
Coverage, Policy, Coding Questions and Mileage Corrections
Submit an IDS ticket to the Parts Department
Supporting Materials
Videos
34 02 21
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34 09 21_TURBINE TYPE NOISE DURING DECELERATION: AUDIBLE FROM THE REAR AXLE
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