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- Porsche 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Porsche 928 Flexplate Clamp Upgrade - Permanent Solution to the 928 Flexplate Problem
Protect Your V8 Engine from Catastrophic Failure
The Porsche 928 V8 engine is known for its performance and
engineering excellence, but it also has a well-documented weakness known as the
flexplate problem. If left unaddressed, this issue can lead to severe internal
engine damage and complete engine failure.
Fits:
- Porsche 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Diagram Ref No 25
This upgraded flexplate clamp is engineered as a functional and permanent solution to prevent crankshaft end float movement and protect the axial thrust bearings.
What the Flexplate Problem Is
In the Porsche 928 automatic transmission setup, the flexplate connects the crankshaft to the torque tube driveshaft. If the clamping system fails or loosens, the crankshaft can be forced forward under load.
When this happens:
- The axial crankshaft thrust bearings wear rapidly
- Excessive crankshaft end float develops
- The crankshaft moves forward into the engine block
- The lower block can be permanently damaged
It only takes 3 to 5 mm of forward crank movement for catastrophic damage to occur. Once the crankshaft bores into the block, the engine is effectively written off.
What This Upgraded Flexplate Clamp Does
This redesigned clamp secures the original flexplate clutch sleeve correctly and evenly, preventing forward crankshaft movement.
Unlike other aftermarket solutions, this clamp design focuses purely on mechanical integrity and correct force distribution.
Key design improvements include:
- Three precision-machined circular segments that fit perfectly around the original flexplate sleeve
- Even clamping force across all segments
- Three high-strength M8 12.9 grade socket head bolts
- Torque specification of 60Nm for secure fastening
- Compact, lightweight design to reduce centripetal forces
Why Other Designs Can Fail
Many flexplate clamp designs use two-piece clamping systems around a three-segment shaft. Basic vector force analysis shows that this design cannot distribute compression force evenly across all segments.
Uneven force distribution leads to:
- Inconsistent clamping pressure
- Potential loosening over time
- Continued crankshaft movement risk
Even Porsche’s original clamp used a simpler two-segment design with a single bolt.
This upgraded clamp eliminates uneven load distribution by using a three-part circular design with equalised clamping forces.
Why You Should Upgrade
You should strongly consider installing this flexplate clamp
if:
- You own a Porsche 928 with automatic transmission
- Your engine has never had the flexplate fix performed
- You are rebuilding or restoring a 928 V8
- You want preventative protection against thrust bearing failure
- You are experiencing signs of crankshaft end float
Symptoms of flexplate issues may include:
- Unusual engine noises
- Difficulty maintaining correct crankshaft end play
- Thrust bearing wear during engine rebuild
- Visible crankshaft forward movement
Installing this upgraded clamp holds the driveshaft securely as originally intended and eliminates the flexplate problem completely when correctly fitted.
Engineering Focused on Functionality
This clamp was developed with one goal: to solve the
mechanical weakness permanently.
- Stronger materials than factory design
- Reduced mass to minimise centrifugal stress
- Balanced clamping across all segments
- Designed for durability under high rotational loads
It provides a long-term preventative solution that protects one of the most valuable components of your 928 — the engine block itself.
Key Benefits at a Glance
- Permanent solution to the Porsche 928 flexplate problem
- Prevents crankshaft forward movement
- Protects thrust bearings and engine block
- Even three-point clamping design
- High-strength 12.9 grade bolts
- Lightweight and mechanically balanced
- Designed for long-term engine protection
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
922421255CL
The product you are viewing cross references to these numbers
- Porsche 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Fits:
Porsche 928 1980-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 17
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92842101226
The product you are viewing cross references to these numbers
- 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 924 Turbo 2.0L 1979-81
- Porsche 924 Turbo 2.0L 1982-84
- Porsche 924 Carrera GT 2.0L 1981
- Porsche 924 Carrera GTS 2.0L 1982
- 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 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Fits:
Porsche 924 Turbo / GT 1976-85
Porsche 924 S 1986-88
Porsche 944 1982-91
Porsche 928 1978-95
Porsche 964 1989-94
Click 'Zoom in' for large parts diagram.
Diagram ref no 4
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92242105103
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
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Fits:
Porsche 924S 1986-88
Porsche 928 1987-95
Porsche 944 1982-91
Porsche 968 1992-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 22
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92242125500
The product you are viewing cross references to these numbers