MMR Performance BMW S55 / N55 One-Piece Crank Hub Upgrade Kit - 4-Pin
*Recommended for high-powered cars over 700HP*
Issues relating to the standard three-piece crank hub on the S55 & N55 engine are (unfortunately) widely known, but these are fully addressed with the installation of the MMR Performance one-piece billet Crank Hub.
MMR Performance now offers this uprated version of our popular Single-Piece Crank Hub, with a 4-Pin dowelled location that locks onto the end of the crankshaft.
The OE crank hub unit's friction plate are known to slip rotationally, causing the timing to alter enough that piston-to-valve contact can occur, leaving owners with a very expensive repair bill.
This 4-pin version of our Single-Piece Crank Hub kit is simply the ultimate solution to preventing this problem before it happens on high horsepower & torque engines.
The centerpiece of the MMR kit is the UK made CNC-machined one-piece crank hub, created from billet EN36 steel that's been heat-treated with a 0.75mm case hardening, making it incredibly strong and durable. Along with this come four aerospace-quality dowel pins 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 4-Pin location ensures that there is now no way that the friction plates can ever slip. With the new OE crank bolt tightened appropriately, this delivers a transformational improvement in reliability versus the OE version.