Lock nut for transmission main shaft. Porsche 911 72-89 / 964 / 993 / 996 turbo / 997 turbo / GT3  ❭  99903403300

Lock nut for transmission pinion shaft - M30 x 1.5
This OE Match transmission pinion shaft lock nut is a replacement M30 x 1.5 retaining nut used within the gearbox assembly. It is designed to match the original-style fitment and function, helping ensure the pinion shaft is secured to the correct specification.
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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

The lock nut secures the transmission pinion shaft within the gearbox assembly. Correct retention of the pinion shaft is essential for maintaining drivetrain alignment, gear mesh, bearing preload, and reliable transmission operation.

Functions
• Replaces the transmission pinion shaft lock nut
• Secures the pinion shaft within the gearbox
• Supports correct gear mesh and drivetrain alignment
• Helps maintain bearing preload where applicable
• Used during gearbox rebuild, pinion shaft service, or transmission repair
• Replaces worn, damaged, rounded, corroded, or previously removed lock nuts
• OE Match replacement for Porsche transmission service.

Why Replace This Part?
Transmission lock nuts are highly loaded retaining components and may be damaged during removal, lose locking integrity, or show thread wear over time. Reusing a worn or damaged lock nut can compromise correct pinion shaft retention and may affect gearbox setup. Replacement is recommended during gearbox overhaul or whenever the lock nut has been removed.

When to Replace This Part
• Gearbox or transmission rebuild is being carried out
• The pinion shaft has been removed or serviced
• The original lock nut is rounded, corroded, damaged, or worn
• Thread condition is poor or uncertain
• Gear mesh, bearing preload, or transmission setup is being checked
• Preventative replacement is required during major drivetrain service
• The vehicle is undergoing Porsche gearbox restoration.

Where it fits on the car
This lock nut fits within the gearbox / transmission pinion shaft assembly. It forms part of the internal transmission retaining hardware.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99903403300

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