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34 05 20_BRAKE NOISE - HELPFUL FACTS FOR EFFECTIVE CUSTOMER COMMUNICATION

SIB 34 05 20
BRAKE NOISE - HELPFUL FACTS FOR EFFECTIVE CUSTOMER
COMMUNICATION

2020-06-15

MODEL
All

SITUATION
Noise while braking

INFORMATION
This bulletin intends to explain some typical brake noise phenomena and provide some recommendations about the
usage and maintenance of the braking system.
The below information can be used during the customer interaction but is not intended as a replacement for a
proper diagnosis
Every customer complaint should be taken seriously and if necessary, addressed using the support of the
BMW Technical Support resources
General information about the root cause of brake noises
The root cause of brake noises can be very different according to the vehicle’s mileage, ambient conditions,
and driving style
Noises occurring in specific conditions (e.g., brakes squeak in the morning or in stop and go traffic) usually
disappear by themselves when the conditions change. By contrast, if noises are present in every condition,
this likely indicates the need for a repair
A differentiation between “break-in phase” and “normal operation” is needed in order to properly address the
customer complaints
“Break-in” phase
When the brake discs (aka rotors) and pads are new, their contacting surfaces need some mileage in order to
adapt to each other and to create a perfect match. This adaptation phase is also called “break-in” phase
Due to the stick-slip of the microscopic surface roughness of the still new contacting surfaces, some noises
(especially squeaking) can arise
The length of the “break-in” phase is strongly dependent on traffic conditions and driving style (customer
profile) and usually lasts for the first 300-400 miles
During the “break-in” phase the brakes should be applied rather gently (if traffic conditions allow), in order to
ease the matching process
Please note that in some extreme cases the “break-in” phase can last up to 1000 miles
Many noises occurring in specific conditions during the “break-in” phase usually disappear with increasing
mileage
After installing new brake pads and/or discs, another “break-in” phase is needed
Procedure for customer complaints during the “break-in” phase
Ask the customer under which driving condition the noise appears and try to reproduce the issue
Check for proper functionality of the brake system
Check the brake discs and pads for abnormal wear and/or corrosion (in this phase abnormal wear and
corrosion are rather unlikely)

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34 05 20_BRAKE NOISE - HELPFUL FACTS FOR EFFECTIVE CUSTOMER COMMUNICATION

If the noise is present only in specific conditions and the brake pad and disc characteristics are within the
normal service specifications for the car mileage:
Inform the customer about the physics of the “break-in” phase (see root causes above)
Suggest the customer to wait until the cars reaches a higher mileage for further investigation
Use your best judgment and your knowledge of the customer profile and driving conditions of your area in
order to identify a reasonable threshold for the end of the “break-in” phase
If the noise is present in every condition and the brake pads and discs characteristics are within the normal
service specifications for the car mileage, please contact the Technical Support for further assistance
“Normal operation” phase
After the “break-in” phase, the contact surfaces of brake discs and pads are matched. The brakes operate in
their optimal design window. This phase is called “normal operation” phase
While the noise should lessen in the “normal operation” phase, a variety of individual factors including driving
style, local environment and weather conditions can influence the amount of noise
Extremely low and high ambient temperatures can change the material properties of the brake pads and
system lubricants. Noises related to extremely low or high temperatures usually disappear by themselves at
normal temperatures.
Noise and occasional vibrations may occur with increasing age and wear of the brake discs and pads as well.
Vibrations are generally caused by thickness variations of discs and/or pads on vehicles with higher mileage.
Procedure for customer complaints during the “normal operation” phase
Ask the customer in which conditions the noise appears and try to reproduce the issue
Check for proper functionality of the brake system
Check the brake discs and pads for abnormal wear and/or corrosion. For brake discs corrosion categorization
and treatment please refer to SIB 34 10 16
If the noise is present only in specific conditions and the brake pads and discs characteristics are within the
normal service specifications for the car mileage:
Inform the customer about the physics of the “normal operation” phase, (see root causes above)
If the noise is present in low temperature conditions, suggest the customer to increase the functioning
temperature of the brakes discs and pads by applying the brakes a few times moderately (if traffic
conditions allow)
If the noise is present after a severe application, ask the customer if the noise disappears after cooling
down the brakes. Please emphasize the importance of cooling down the brakes after severe use
After severe use, try to avoid applying the brake pedal while waiting at a traffic light. Instead shift the
transmission into the “P” position.
If the noise is present in every condition and the brake pad and disc characteristics are within the normal
service specifications for the car mileage, please contact the Technical Support for further assistance
Corrosion
Driving and parking repeatedly in corrosive environments, such as those with high humidity and road salt
content can accelerate the disc corrosion process
Long vehicle down times can result in strong disc corrosion that cannot be removed simply by brake
application
Procedure for customer complaints regarding corrosion (visual or corrosion-related noise noises and /or
vibration)
For brake disc corrosion categorization and treatment, refer to SIB 34 10 16
Inform the customer about the following best practices:

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34 05 20_BRAKE NOISE - HELPFUL FACTS FOR EFFECTIVE CUSTOMER COMMUNICATION

Moderate to sporty brake application (ABS intervention) can remove light surface corrosion (i.e., after
letting the car parked over the weekend). Make sure that this procedure does not endanger other traffic
Avoid long standing times if possible
After a car wash, gently press the brake pedal every few miles, ensuring that this action does not
endanger other traffic. The heat generated during braking dries brake discs and brake pads and
protects them against corrosion. This procedure is called “dry braking”
The dry braking is strongly recommended if the car has been washed before a long storage time (for
example before winter)
Dry braking is also suggested when roads are wet, salted, or in heavy rain. Always make sure that this
action does not endanger other traffic
Other maintenance best practices
When cleaning the wheels:
Use acid/alkaline-free wheel cleaners to reduce the risk of corrosion
Avoid an excessive use of tire shine products, as they might contaminate the brake pad surface
Avoid pointing high-pressure cleaners directly onto brake parts. Using high-pressure cleaners can cause
brake components to bind, resulting in brake noises
In addition, BMW North America has published the following customer brochure:

“BMW Brake Systems: High-Performance
Stopping Power” (Shown).

Supporting Materials
picture_as_pdf B34 05 20 BMW_Brake_Brochure.pdf

Copyright ©2020 BMW of North America, Inc.
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June 2020

B34 50 20 Attachement 1
THE EVOLUTION OF
STATE-OF-THE-ART.

© 2020 BMW of North America, LLC. This brochure, or any portion thereof,
may not be reproduced without the express written permission of BMW of
North America, LLC. The BMW name and logo are registered trademarks.
All rights reserved. European vehicles may be shown. Printed in USA.
BRK300M

BMW BRAKE
SYSTEMS:
HIGH PERFORMANCE
STOPPING POWER.

BMW 507 ▪ 1956–1959
Drum brake stopping distance: approx. 193 ft.*

BMW M1 ▪ 1978–1981
Disc brake stopping distance: approx. 134 ft.*

BMW USA

BMW 8 ▪ 2019
Disc brake stopping distance: approx. 100 ft.*
bmwusa.com

*From 60 to 0 MPH.

The Ultimate
Driving Machine®

STOPPING STARTS HERE.
▪ Powerful car requires a powerful brake system
▪ T
he BMW brake systems are designed to deliver
the ultimate brake performance
▪ W
e select materials with an emphasis
on performance over a wide range of
operating conditions

OPTIMAL USAGE AND
MAINTENANCE.
To ensure optimum brake performance, please consider
following guidelines:

BREAK-IN PHASE.

▪ When the brake discs and pads are new, their
contacting surfaces need some mileage in order to
adapt to each other. This adaptation phase is called
“break-in” phase

▪ The length of the “break-in” phase is strongly
dependent on traffic conditions and driving style and
usually lasts for the first 300-400 miles
▪ During the “break-in” phase the brakes should be
applied rather gently in order to ease the matching
process. Make sure that this procedure does not
endanger other traffic
▪ The break-in process should be repeated after
installing new brake pads.

BRAKE NOISE.
▪ Some brake noise is normal – especially during the
break-in phase. While the noise should lessen after
the pads are fully bedded onto the discs, a variety of
individual factors will influence the amount of noise
including driving style, your local environment and
weather conditions
▪ Noises occurring in specific conditions like
extremely low and high ambient temperatures
usually disappear by themselves when the
conditions change. By contrast, if noises are present
in every condition, this likely indicates the need of a
repair

▪ After car wash, gently press the brake pedal every
few miles. The heat generated during braking dries
brake discs and brake pads and protects them
against corrosion. Make sure that this procedure
does not endanger other traffic

OTHER MAINTENANCE BEST
PRACTICES.
▪ Use acid/alkaline-free wheel cleaners to reduce
the risk of corrosion
▪ Avoid an excessive use of tire shine products, as
they might contaminate the brake pad surface

▪ Noise and vibration may occur with increasing
age and wear of the brakes. These symptoms can
indicate that your vehicle may need brake service

▪ Avoid pointing high-pressure cleaners directly
on brake parts. Using high-pressure cleaners can
cause brake components to bind, resulting in
brake noises

BRAKE DISCS SURFACE
APPEARANCE.

BRAKE DUST.

▪ Brake rotors and pads are parts subjected to wear
and corrosion and have therefore to be maintained
or replaced from time to time
▪ Driving and parking repeatedly in corrosive
environments, such as those with high humidity
and salt content, can accelerate the natural disc
corrosion process
▪ Moderate to sporty brake application can remove
light surface corrosion. Make sure that this
procedure does not endanger other traffic

▪ The high friction generated between discs and
pads while braking wears the brake discs and pads
causing some brake dust
▪ The latest generation of BMW brake pads are
optimized to minimize brake dust. Brake dust can
be normally cleaned off easily. Wheel cleaning is
recommended on a regular bases

SPORT BRAKES.
▪ Optional sport brakes are available for a variety
of BMW vehicles. In addition to enhanced
performance, you may experience more brake dust
and, in some cases, slight noises when braking