MMX Performance BMW S55 / N55 One-Piece High HP Crank Hub Upgrade Kit - 4-Pin
The MMX Performance BMW S55 / N55 One-Piece High HP Crank Hub Upgrade Kit (4-Pin) is the ultimate solution for addressing one of the most well-documented failure points in modern BMW turbocharged engines. The factory three-piece crank hub design is known to slip under high load conditions, particularly in tuned or high-horsepower applications, which can result in catastrophic engine damage. MMX has engineered a complete solution that eliminates this risk entirely.
At the core of the kit is a precision CNC-machined, one-piece crank hub manufactured in the UK from billet EN36 steel. This material is heat-treated with a 0.75mm case hardening process, delivering exceptional strength, wear resistance, and long-term durability. Unlike the factory friction-based system, the MMX hub uses a mechanical locking approach with four aerospace-grade dowels that secure the hub directly to the crankshaft, preventing any possibility of slip.
This four-pin design, combined with the single-piece construction, ensures that timing integrity is permanently maintained even under extreme load, high boost, and aggressive driving conditions. When paired with the correct torque procedure using the supplied new OE crank bolt, the result is a significant increase in engine reliability and peace of mind.
To support accurate installation, the MMX kit includes a complete drilling jig system designed specifically for professional installation. This ensures precise alignment when modifying the crankshaft, allowing for safe and repeatable installation. The kit includes a bolt-on drilling guide, location hardware, and a high-speed steel drill bit, providing everything required for proper fitment.
This upgrade is strongly recommended for high-performance vehicles, particularly those exceeding 700 horsepower, where the risk of crank hub slip is significantly increased.
Product Details
- One-piece crank hub design eliminates OEM slip risk
- Four aerospace precision-machined dowels for mechanical locking
- Manufactured from heat-treated billet EN36 steel
- 0.75mm case hardened for maximum durability
- Includes new OE crank bolt
- Complete installation kit with drilling jig and HSS drill bit
- Available with optional capture plate for additional security
- Designed for high-performance and high-horsepower applications
- SKU: MMR20-1004
Vehicle Applications
- BMW F80 M3
- BMW F82 / F83 M4
- BMW F87 M2
- BMW F87 M2 Competition / CS
- BMW F22 / F23 2 Series
- BMW F30 / F31 3 Series
- BMW F32 / F33 4 Series
Notes
- Includes a 1-year manufacturer warranty against defects in materials and workmanship
- Designed and tested in the United Kingdom
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Installation Notes
- Professional installation required due to crankshaft modification
- BMW S55 and N55 crank bolt torque: 100 Nm initial torque plus 270 degrees