ENU 109/21

4407

or
99736118700

 Circlip
– Central wheel lock

1 piece

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

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

Work Procedure: 1

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

Material transfer for brake disc/wheel hub

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Service
109/21 ENU

4407

4

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 material transfer or corrosion, if available, with pictures.

3

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

4

Check contact surface of brake disc, wheel hub and
rim for dirt and clean them if necessary.
4.1

Clean wheel assembly:

Contact surfaces of 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
microfibre cloth with brake cleaner and rub
off the wheel hub ( Cleaning wheel hub -1-)
with it.

Cleaning wheel hub

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4

Service
ENU 109/21

4407

4.2

Symptom-based workshop manual

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 microfibre cloth with brake cleaner and
rub off the cleaned areas with it.

Cleaning brake disc hub
4.3

Clean the contact surfaces between the rim
and brake disc ( Contact surfaces between
rim / brake disc -1 and 2-) using a microfibre
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 driving pins.

Contact surfaces between rim / brake disc

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Symptom-based workshop manual
5.1

Check material transfer at the driving pins.
If a material transfer has taken place, the
driving pins must be replaced.  Material
transfer on driving pin

5.2

Subsequent torque 22 Nm (16.2 ftlb.)of
screw connection for wheel driver pin 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.

Service
109/21 ENU

4407

4

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

 Workshop Manual '465419 Removing and

Material transfer on driving pin

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 geometric discrepancies
Information
Geometrical discrepancies may be due to the following factors:
•

Damaged parts

•

Wear

•

Use of new and old parts

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Symptom-based workshop manual

ENU 109/21

4407

Work Procedure: 1

Check brake discs, wheel hub and rim for damage,
e.g. notches or "dents" due to incorrect assembly.
 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 noise.
2.1

Check the inside of the rim for evenness at
least at six different positions (approx. every
60°) using a straight edge (e.g. 12" Starret
380) and a feeler gauge at the measuring
points  Measuring points on inside of rim
-Arrow-.

Checking rim
Dimensions
( )

up to 0.1 mm

Evenness OK.

(✗)

from 0.11 mm

Evenness not OK.

Document all measurements with photos.

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Assessment

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Service

Symptom-based workshop manual

109/21 ENU

4407

4

If there are uneven surfaces, 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

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 Remove and install front brake disc'

2

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

Working position and PCSS encryption
Labor position:
APOS

Labor operation

44074941

Reworking wheel mount (left)

44074942

Reworking wheel mount (right)

I No.

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Service
ENU 109/21

4407

Symptom-based workshop manual

PCSS encryption:
Location (FES5)

4407A

Wheel mount central bolt

Damage type (SA4)

9735

Repair according to PAG instructions

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.

© 2023 Porsche Cars North America, Inc.

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