MMX 4-Pinned crank hub | BMW S55 | N55

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