Symptom-based workshop manual

Service
109/21 ENU

4407

4

Noise Symptom – Clicking Noises from Around the Front Axle: Observe Specified
Procedure (SY 109/21)
Model Line:

911 (992)

Model Year:

As of 2020

Equipment:

Central wheel lock (M-no. 1PJ)

Concerns:

Front wheel mounting

Symptom:

The customer complains about clicking noises from around the front axle when turning the steering wheel
sharply or turning the vehicle while driving slowly.

Cause:

Micro-movements can occur between the contact surfaces of the wheel and brake disc while driving.
These micro-movements can mainly be caused by the following:
•
•
•

Reduced preload on the central wheel lock
Reduced friction coefficient between the surfaces
Geometrical discrepancies

This can cause the rim material to be removed and transferred to the brake disc.
The transferred material can fuse with the brake disc, causing a stick-slip effect. This results in the
clicking noises while turning the wheel.
Information
The stick-slip effect is the jerking motion that can occur while two solid bodies are sliding over each other.
This phenomenon occurs when a body is moved whose static friction is significantly higher than the
sliding friction.
Remedial
Action:

Check the front wheel mounting components as described below and carry out the required remedial
action, depending on the result of the check.
When checking the components, always follow the sequence described below:
•
•
•

Check central wheel lock. For instructions, see:  Technical Information 'Checking central wheel
lock'
Check contact surfaces of the rim, brake disc and wheel hub for friction loss. For instructions, see:
 Technical Information 'Reduced friction coefficient between the surfaces'
Check the rim, brake disc and wheel hub for geometrical discrepancies. For instructions, see: 
Technical Information 'Geometrical discrepancies'

AfterSales

Nov 24, 2021
Page 1 of 12

4

Service

Symptom-based workshop manual

ENU 109/21

4407

Information
The wheel design with central lock was originally developed for race track driving. It allows the wheels to
be changed quickly during a race. Today, the wheel and hub designs with central lock for road vehicles
are significantly different to those of pure racing cars. Given this, the following guidelines and precautionary measures must always be observed when removing or installing the wheels on a road vehicle with
central wheel lock.
•

The vehicle must be on a lifting platform and the wheels must be hanging freely (no contact with the
floor) while tightening the central lock nut. This ensures that the wheel is centered correctly on the
hub.

•

The parking brake must not be used to counter the rear wheels while tightening. The parking brake
mechanism does not tolerate the high forces while tightening the central wheel lock and can be
damaged. The damage may not be immediately apparent. This applies in particular to the motorized
electronic parking brake actuators.

•

Impact tools must never be used for loosening, removing or tightening the central wheel lock. The
nut and hub can be damaged and the damage may not be immediately apparent.

•

Only a calibrated, high-quality standard torque wrench with sufficient load capacity and levering
effect may be used for tightening the central wheel lock. The use of torque multipliers is not
approved for use on Porsche vehicles.

•

The specified final tightening torque must be reached while turning the torque wrench with a smooth,
continuous motion.

•

The required lubricant must be applied to the contact surfaces of the central wheel lock and rim
in accordance with regulations. For more information, see:  Workshop Manual '440737 Disassembling and assembling central wheel lock'

•

If the central wheel lock, wheel hub or rim is new, the central wheel lock must be tightened to the
specified final tightening torque, loosened and then loosened and tightened again three more times.
This will eliminate any geometrical discrepancies.

Required parts and materials
Parts Info:

Parts required:
Part No.

Designation
– Location

Qty.

WHT008186

 Cylinder screw, M12 x 1.5 x 62
– fixed-calliper, front axle
– M-no. 1LR, 1LS

4 ea.

or
9A70075850

Nov 24, 2021
Page 2 of 12

 Cylinder screw, M12 x 1.5 x 95
– fixed-calliper, front axle
– M-no. 1LQ, 1LX

AfterSales

4 ea.

Symptom-based workshop manual
Materials:

Service
109/21 ENU

4407

4

Required materials (usually already available at the Porsche dealer):
Part No.

Designation

Qty.

00004330508

 Mounting paste (100 gram/ 3.52 oz tube)

2 grams/ 0.07 oz

Required tools
Tools:

•
•
•
•
•
•
•
•

Straight-edge, e.g. 12-inch Starret 380
Feeler gauge, 0.05 mm
Brass brush
Microfiber cloth
Brake cleaner
9451 - Socket wrench
9794 - Assembly aid
9796 - Socket wrench

Preparatory work
Work Procedure: 1

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

Checking central wheel lock
Information
Reduced preload on the central wheel lock may be due to:
•

Reduced amount of grease on the cone of the central wheel lock or on the thread and external
diameter of the wheel hub

•

A damaged central wheel lock bolt

•

A damaged cone on the rim

Information
If one or more of the central bolts is damaged, it must be replaced. Make sure that the central bolt is sufficiently greased. For instructions, see:  Workshop Manual '440737 Disassembling and assembling
central wheel lock'
Work Procedure: 1

2

Disassemble central wheel lock.
For instructions, see:
 Workshop Manual '440737 Disassembling and assembling central wheel lock'
Check that the central wheel lock is coated with a sufficient amount of lubricant  Lubricating film
on central wheel lock and check for cracks, deformation  Example of damage and other signs of
damage. Damage can occur at the following points:
•

Thread of the wheel hub

AfterSales

Nov 24, 2021
Page 3 of 12

4

Service
4407

Symptom-based workshop manual

ENU 109/21

•
•
•

Thread of the central wheel lock
Cone of the rim
Cone of the central wheel lock

Lubricating film on central wheel lock

Nov 24, 2021
Page 4 of 12

AfterSales

Symptom-based workshop manual

Service
109/21 ENU

4407

4

Example of damage

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.
Parts Info:

Parts required for one side of the vehicle if necessary:
Part No.

Designation
– Location

Qty.

992601119B

 Central lock, complete

1 ea.

or
PAF008814

 O-ring
– Central wheel lock

1 ea.

or

AfterSales

Nov 24, 2021
Page 5 of 12

4

Service

Symptom-based workshop manual

ENU 109/21

4407

9P1601213

 Base
– central lock

1 ea.

or
9P1601213

 Cone ring for central lock
– central lock

1 ea.

or