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 engines are well known, but these issues are fully addressed with the installation of the MMR Performance 4-pinned single-piece crank hub. The option to add a Capture Plate provides ultimate security.

Single-Piece Crank Hub with 4-Pin Dowelled Location

The centerpiece of the MMR kit is the UK-made CNC-machined one-piece crank hub, created from billet EN36 steel and 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 the end of the crankshaft, along with a brand new OE bolt.

Installation of these dowels is not a DIY job. To assist professionals, the MMR kit includes a full installation jig with a bolt-on drilling guide, a location bolt for the guide, and an HSS rolled high-speed drill bit.

The single-piece design combined with the four-pin location ensures that the friction plates cannot slip. With the new OE crank bolt tightened appropriately, this delivers a significant improvement in reliability compared to the OE version.

Product Features

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

Additional Information

The optional MMR capture plate ensures complete peace of mind by preventing the crank bolt from loosening due to engine 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 impossible for the bolt to come undone. The capture plate part number is MMR20-1002.

Fitting Information

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

This product fits all models with N55 and S55 engines. Most popular models include:

• BMW M2 F87 2015-2018
• BMW M2 Competition F87 2018-2021
• BMW M3 F80 2014-2019
• BMW M4 F82 2014-2020
• BMW M135i F2x 2011-2019
• BMW M235i F2x 2013-2020
• BMW 335i F3x 2011-2019
• BMW 435i F3x 2013-2020