9P1601138

 Circlip
– Central wheel lock

Checking contact surfaces of the rim, brake disc and wheel hub for friction loss
Information
A reduced friction coefficient between the surfaces can be due to:

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•

Material transfer from rim to brake disc or from rim to driver pin

•

Anti-corrosion oil on the contact surfaces

•

Contact surfaces dirty, e.g. brake dust

•

Hub grease on the contact surface

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Symptom-based workshop manual
Work Procedure: 1

Service
109/21 ENU

4407

4

Check the mounting surface of the wheel hub and inside of rim for material transfer or corrosion.
 Material transfer on brake disc/wheel hub

Material transfer on brake disc/wheel hub
Information
If there has been material transfer from the rim to the brake disc, the brake disc must be replaced.
For instructions, see:
 Workshop Manual '465019 Removing and installing front brake disc'
2

Document any material transfer or corrosion by taking photos.

3

Remove front brake discs.  Workshop Manual '465019 Removing and installing front brake disc'

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Service
ENU 109/21

4407
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Symptom-based workshop manual

Check contact surface of the brake disc, wheel hub
and rim for soiling and clean it if necessary.
4.1

Cleaning wheel assembly:

Contact surfaces on brake
disc, wheel hub, rim
Brush off wheel hub ( Cleaning wheel hub
-1-) using a brass brush until all particles
of dirt have been removed. Then, spray a
microfiber cloth with brake cleaner and use
it to rub off the wheel hub ( Cleaning wheel
hub -1-).

Cleaning wheel hub

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Symptom-based workshop manual
4.2

Service
109/21 ENU

4407

4

Clean brake dust off the inner brake disc hub
( Cleaning brake disc hub -1-) and brush
off the contact surface between the brake
disc and wheel hub ( Cleaning brake disc
hub -2-) using a brass brush until all particles
of dirt have been removed. Then, spray a
microfiber cloth with brake cleaner and use it
to rub off the cleaned areas.

Cleaning brake disc hub
4.3

Clean the contact surfaces between the
rim and brake disc ( Contact surfaces
between rim and brake disc -1 and 2-) using
a microfiber cloth and brake cleaner (do not
use a brass brush).

Information
Always make sure that the cleaned surfaces are kept
clean until assembly is complete.
5

Check driver pins.

Contact surfaces between
rim and brake disc

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Symptom-based workshop manual

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4407

5.1

Check material transfer on the driver pins.
If material transfer has occurred, the driver
pins must be replaced.  Material transfer
on driver pins

5.2

Check threaded joint for wheel driver pins for
a subsequent torque of Subsequent torque
22 Nm (16 ftlb.) and then remove brake
disc. If the pins can still be turned, replace
pins and screws and clean the thread and
contact surfaces to remove any remaining
screw-locking material.

 Workshop Manual '465319 Removing and
installing rear brake disc'

Material transfer on driver pins

 Workshop Manual '465419 Removing and installing rear PCCB brake disc'
5.3

Check wheel driver pins for damage. If there are visible signs of damage, replace pins and
screws and clean the thread and contact surfaces to remove any remaining screw-locking
material.

Information
If using new parts, the procedure for tightening the wheel as described in the Workshop Manual 
Workshop Manual '440519 Removing and installing wheel with central bolt' must be carried out three
times.

Checking rim, brake disc and wheel hub for geometrical discrepancies
Information
Geometrical discrepancies may be due to the following factors:

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•

Damaged parts

•

Wear

•

Use of new and old parts

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Symptom-based workshop manual

Work Procedure: 1

Service
109/21 ENU

4407

4

Check brake discs, wheel hub and rim for damage,
e.g. notches or "dents" due to incorrect installing.
 Example of damage

Example of damage
2

Check contact surface of the rim.
To ensure that the surface is flat, check the rim using
a ruler and feeler gauge.
Uneven surfaces can affect the rim and cause noises.
2.1

Check that the inside of the rim is flat at at
least six different positions (approx. every
60°) using a straight-edge (e.g. 12-inch
Starret 380) and a 0.05 mm feeler gauge at
the measuring points  Measuring points on
inside of rim -Arrow-.
Document all measurements by taking
photos.
Checking the rim
If the surface is uneven, replace the affected
rim.

Information
If using new parts, the procedure for tightening the wheel
as described in the Workshop Manual  Workshop Manual
'440519 Removing and installing wheel with central bolt'
must be carried out three times.

Measuring points on inside of rim

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Symptom-based workshop manual

ENU 109/21

4407

Concluding work
Work
Procedure:

Information
When installing a wheel, the three tightening steps must always be observed as described in the
Workshop Manual  Workshop Manual '440519 Removing and installing wheel with central bolt' and the
following special tools must be used:
•

9451 - Socket wrench

•

9794 - Assembly aid

•

9796 - Socket wrench

The central bolt must be tightened in one continuous movement. This is the only way to ensure that the
specified tightening torque is reached.
1

Install front brake discs.  Workshop Manual '465019 Removing and installing front brake disc'

2

Install front wheels.  Workshop Manual '440519 Removing and installing wheel with central bolt'

Invoicing
Invoicing:

For documentation and warranty invoicing, enter the labor operations, PCSS coding and part numbers
specified below in the warranty claim:

APOS

Labor operation

44074941

Reworking wheel mounting (left)

44074942

Reworking wheel mounting (right)

I No.

PCSS coding:
Location (FES5)

4407A

Central bolt for wheel mounting

Damage type (SA4)

9735

Repair in accordance with PAG instructions

References:

 Workshop Manual '440519 Removing and installing wheel with central bolt'
 Workshop Manual '440737 Disassembling and assembling central wheel lock'
 Workshop Manual '465019 Removing and installing front 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.

© 2021 Porsche Cars North America, Inc.

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