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Lock nut for transmission main shaft. Porsche 911 72-89 / 964 / 993 / 996 turbo / 997 turbo / GT3 ❭ 99903403300
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 TURBO 2000-05
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MK1 GT2 2007-09
- Porsche 997 MKII GT3 / GT3 RS 2010-11
- Porsche 997 MKII Turbo 2010-13
- Porsche 997 MKII GT2 RS 2011-13
The Genuine Porsche 99903403300 transmission pinion shaft lock nut is an OE M30 x 1.5 shouldered lock nut for selected Porsche manual gearbox applications, including 911 1972–1989, 964, 993, 996 Turbo, 997 Turbo and GT3 models. It secures key transmission shaft components and is ideal for gearbox rebuilds, transmission repairs or restoration using Genuine Porsche hardware.
Sold individually
Fits:
Porsche 911 - 1972 to 1989 (915 and G50)
Porsche 964 - 1989 to 1994
Porsche 993 - 1994 to 1994
Porsche 996 turbo - 2001 to 2005
Porsche 997 turbo - 2007 to 2013
Porsche 996 GT3 - 2003 to 2005
Porsche 997 GT3 - 2007 to 2011
Manual transmission
Diagram ref no 20
This nut is used in selected Porsche manual gearbox assemblies, including 915, G50 and later Turbo / GT gearbox applications where specified.
What This Part Does / Functions
• Secures transmission shaft components in position
• Helps maintain correct gearbox shaft assembly preload and alignment
• Supports proper operation of the pinion shaft / main shaft assembly
• Helps prevent loosening under drivetrain load and vibration
• Provides correct OE Porsche M30 x 1.5 thread and shouldered nut design
• Replaces a worn, damaged, previously removed or incorrectly reused lock nut
• Supports correct transmission rebuild and gearbox service procedures
• Maintains factory Porsche gearbox hardware specification.
Why Replace This Part?
Transmission lock nuts are critical gearbox fasteners. During gearbox rebuilds or shaft service, the original nut may be removed, disturbed, damaged or no longer suitable for reuse. A worn, distorted or incorrectly secured shaft nut can affect gearbox assembly, shaft retention and long-term reliability. Replacing it with a Genuine Porsche OE transmission shaft lock nut helps ensure the gearbox is rebuilt using the correct factory-specified hardware.
When to Replace This Part
• During manual gearbox rebuild or overhaul
• When servicing the transmission main shaft or pinion shaft
• If the original nut is worn, damaged, distorted or corroded
• If the nut has been removed during gearbox disassembly
• During differential, gear set or shaft bearing replacement
• If the original lock nut no longer secures correctly
• When restoring a Porsche gearbox with correct OE hardware
• Whenever Porsche workshop procedure recommends replacement after removal.
Where It Fits on the Car
This lock nut fits inside the manual transmission / gearbox assembly. It is used on the transmission main shaft or pinion shaft, depending on the gearbox type and application.
Installation requires correct Porsche gearbox tools, torque procedure and workshop specifications. This is a specialist transmission component and should be fitted by an experienced Porsche gearbox technician.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903403300
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
- Porsche 968 3.0L 1992-94
- Porsche 968 Sport 3.0L 1994-95
- Porsche 968 CS 3.0L 1993-95
- Porsche 968 Turbo S 3.0L 1993-94

Fits:
Porsche 996 1998-2001
Porsche 986 Boxster 1997-04
Porsche 987 Boxster 2005-08
Porsche 987 Cayman 2007>>
Porsche 968 1992-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 1
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99639701000
The product you are viewing cross references to these numbers
- Porsche 924S 2.5L 1986-87
- Porsche 924S 2.5L 1988
- Porsche 944 2.5L 8V 1982-87
- Porsche 944 2.7L 8V 1988-89
- Porsche 944S 2.5L 16V 1987-88
- Porsche 944S2 3.0L 16V 1989-91
- Porsche 944 Turbo 2.5L 8V 1985-88
- Porsche 944 Turbo 2.5L 8V 1989-91
- Porsche 944 Turbo S 2.5L 8V 1988
- Porsche 968 3.0L 1992-94
- Porsche 968 Sport 3.0L 1994-95
- Porsche 968 CS 3.0L 1993-95
- Porsche 968 Turbo S 3.0L 1993-94
Fits:
For cars with MANUAL transmission
Porsche 924S 1986-88
Porsche 944 1982-91
Porsche 968 1992-95
Diagram ref no 31
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
016311113C
The product you are viewing cross references to these numbers
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster S 986 3.2L 2003-04
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 996 TURBO 2000-05
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 968 CS 3.0L 1993-95

Fits:
Porsche 911 Carrera 3.2L 1984-89
Porsche 911 Turbo 3.3 1978-89
Porsche 964 1989-94
Porsche 993 1995-98
Porsche 996 1998-05
Porsche 986 Boxster 3.2L 2000-04
Porsche 986 968CS 1993-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 20
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99911334741
The product you are viewing cross references to these numbers
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