MMR 4-Pinned crank hub MMR20-1004 for BMW S55 / N55

MMR 4-pinned single piece crank hub for BMW N55 & S55

Engine failures caused by the standard three-piece crank hub on the S55 and N55 engine are (unfortunately) well known, but these are fully addressed with the installation of the MMR Performance 4-pinned single-piece crank hub. Together with the option of adding our Capture Plate for ultimate security.

Single-piece crank hub with a 4-pin dowelled location that locks onto the end of the crankshaft.

The centrepiece of the MMR kit is the UK made CNC-machined one-piece crank hub, created from billet EN36 steel that's heat-treated with a 0.75mm case hardening, making it incredibly strong and durable. Included are four aerospace precision machined dowels that mechanically lock the hub to end of the crank itself, plus a brand new OE bolt.

Installation of these dowels is certainly not a DIY job. But, to make the job easier for the professionals, ensuring that the required crank modifications are made safely and accurately, the MMR kit also includes a full installation jig that includes a bolt-on drilling guide, a location bolt for this guide, plus an HSS rolled high-speed drill bit.

Together, the single-piece design combined with the four-pin location ensures that there is simply no way that the friction plates can ever slip. With the new OE crank bolt tightened appropriately, this delivers a transformational improvement in reliability and peace of mind versus the OE version.

Product features

• Single-piece design.
• X4 aerospace precision machined dowels.
• Machined from heat-treated billet EN36 steel.
• Available to purchase with capture plate.
• Complete kit with everything you need including drilling jig and drill bit.
• The ultimate solution to preventing crank hub failure.

Additional information

Finally, alongside our crank hubs, the optional MMR capture plate ensures that owners have complete peace of mind.

Our capture plate removes the possibility for the crank bolt to be able to loosen with the engine's vibrations or harmonics. The capture plate is an additional billet aluminium hat that securely bolts over the entire head of the crank bolt, making it literally impossible for the bolt to come undone. The capture plate part number is MMR20-1002.

Fitting informations

BMW S55 and N55 bolt torque: 100Nm initial torque plus 270 degrees.