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- 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
The crankshaft gear wheel is installed on the front of the crankshaft and is responsible for driving the timing belt system that synchronizes the rotation of the crankshaft with the camshaft. In Porsche 944 and 968 engines, this gear forms the primary drive point for the timing system, ensuring that valve timing remains precisely aligned with piston movement.
Fits:
Porsche 944 1986-1991 with engine types M 44.40 and M 44.41
Porsche 968 1992-95 with engine types M 43 and M 44.
Diagram ref no 15
This OE Match version of part number 94410512507 is designed to match the factory specifications used in Porsche engines, providing accurate tooth geometry and reliable engagement with the timing belt and associated components.
The crankshaft gear transfers rotational motion from the crankshaft to the timing belt system. This ensures the camshaft opens and closes the engine valves at the correct time relative to piston movement, maintaining proper combustion and engine performance.
If the gear becomes worn or damaged, the timing system may lose accuracy, which can affect engine efficiency and reliability.
Function
• Timing Drive: Transfers crankshaft rotation to the camshaft timing system
• Engine Synchronization: Maintains precise timing between pistons and valves
• Power Transmission: Drives the timing belt mechanism
• Engine Reliability: Ensures stable and accurate valve timing
Timing system components are subjected to constant load and engine vibration. Over time the gear teeth may wear or become damaged, which can affect timing belt alignment and engine timing accuracy. Replacing the crankshaft gear during major engine service or timing system overhaul helps ensure precise timing operation and protects other components in the engine’s timing system.
Consider replacing the crankshaft gear wheel when:
• Performing a timing belt or engine rebuild service
• Gear teeth show wear or damage
• Timing system components are being replaced
• Engine timing alignment issues are detected
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
94410512507
The product you are viewing cross references to these numbers
- 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
Crankshaft Standard (STD)
The
standard size crankshafts are key rotating components used in Porsche 993
engines and 996 Turbo models.
Fits:
Diagram ref no 1
The crankshaft delivers the precise journal dimensions, balance and strength needed for the high-performance flat-six architecture. Designed to maintain original tolerances, a standard-size crankshaft ensures correct bearing clearances, smooth rotation and reliable power delivery—crucial for both road and track-driven Porsches.
For any engine rebuild, restoration or major service involving these models, choosing a correctly machined and precision-balanced standard size crankshaft is essential to restoring authentic performance and long-term reliability.
What These Standard Size Porsche Crankshafts Do
Designed to work at the core of the bottom end
assembly, these crankshafts:
- Convert piston movement into rotational torque to power the drivetrain
- Maintain exact journal diameters for correct bearing oil film clearance
- Provide engine balance across all RPM ranges—crucial for high-revving Porsche flat-six engines
- Facilitate internal lubrication via precision oil galleries
- Support smooth, strong and consistent power delivery Ensure structural integrity under boost conditions in 996 turbo engines
These crankshafts are engineered to perform reliably under demanding thermal, mechanical and load environments typical of Porsche performance models.
Why Porsche 993 & 996 turbo Crankshafts Can Fail
Even though Porsche flat-six crankshafts are
exceptionally robust, years of use, high RPM and turbocharged forces can lead
to failure. Common causes include:
- Oil starvation or low pressure causing severe journal scoring
- Bearing shell failure damaging journals and lubrication paths
- Metal fatigue from aggressive driving, detonation or over-boost scenarios
- Overheating weakening the crankshaft material
- Contamination in oil scoring journals and reducing bearing life
- Imbalance from previous poor machining or unbalanced accessories
- High mileage fatigue affecting torsional stability
Symptoms of failure include persistent vibration, knocking noises, falling oil pressure, bearing debris in oil or visible wear during teardown.
Why You
Should Replace a Worn Crankshaft
Replacing a damaged crankshaft with a precision-built
standard size alternative engineered to match original performance
characteristics is crucial to achieving a reliable and long-lasting Porsche
engine rebuild.
Key benefits of replacement include:
- Restored correct bearing clearances for stable oil pressure
- Smoother rotation and reduced engine vibration
- Improved reliability for high-load, high-RPM and turbocharged conditions
- Prevention of catastrophic bottom-end failures
- Extended service life for bearings, rods and pistons
- Enhanced performance consistency and engine smoothness
With Porsche 993 and 996 Turbo engines now highly valued by enthusiasts, a precision crankshaft is foundational to any proper rebuild or restoration.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310202102
The product you are viewing cross references to these numbers
- 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 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 MKII GT3 / GT3 RS 2010-11
- Porsche 997 MKII Turbo 2010-13
This OE Match crankshaft main bearing O-ring is a replacement sealing ring for Porsche 911 1978–1989, 964, 993, 996 Turbo, 997 Turbo, and GT3 models. Measuring 51 x 4.5, it is designed to match the original-style fitment and sealing function within the crankshaft / main bearing area.
Sold individually
Fits:
Porsche 911 1978 - 1989
Porsche 964 1989 - 1994
Porsche 993 1995 - 1998
Porsche 996 Turbo 3.6L 2001 - 2005
Porsche 996 GT3 3.6L 1999 - 2005
Porsche 997.1 Turbo 3.6L 2007 - 2009
Porsche 997.2 Turbo 3.6L 2010 - 2013
Porsche 997 GT3 3.6L / 3.8L / 4.0L 2007 - 2011
Diagram ref no 21
The crankshaft main bearing O-ring helps seal the relevant bearing or housing connection to prevent oil leakage and maintain correct engine oil sealing. A properly sealing O-ring is essential for protecting engine components and maintaining oil system integrity.
What This Part Does / Functions
• Replaces the crankshaft main bearing
• O-ring Helps seal the crankshaft / main bearing housing area
• Supports correct engine oil sealing
• Helps prevent oil leaks from aged or flattened seals
• Suitable for engine rebuild, crankshaft, or bearing service
• Replaces hardened, cracked, flattened, swollen, or damaged O-rings
• OE Match replacement for Porsche engine sealing repair.
Why Replace This Part?
O-rings can harden, flatten, crack, swell, or lose sealing ability due to heat, age, oil exposure, pressure, and engine service work. A worn or damaged crankshaft main bearing O-ring may allow oil seepage or leakage, affecting engine cleanliness and oil system reliability. Replacement is recommended whenever the related engine components are removed or when oil leakage is present.
When to Replace This Part
• Engine rebuild or major engine service is being carried out
• Crankshaft or main bearing components are being serviced
• Oil leakage is present around the related sealing area
• The original O-ring is hardened, flattened, cracked, or damaged
• Bearing housing or crankshaft sealing components have been removed
• Preventative replacement is required during engine assembly
• The vehicle is undergoing Porsche engine restoration
Where it fits on the car
This O-ring fits within the engine crankshaft / main bearing sealing area. Exact position can vary depending on engine type and model-specific crankcase layout.
Related reference numbers
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99970728541
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