MMX Performance - CRANK HUB SINGLE PIECE UPGRADE I BMW S55 I N55

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, together with the option to add our Capture Plate for ultimate security. 

The OE crank hub unit's friction plate are known to slip, causing the timing to alter enough that piston-to-valve contact can occur and, if not totally standard and within the warranty period, leaves owners with a very expensive repair bill!

We have developed this Single-Piece Crank Hub together with our optional Capture Plate to ensure owners have complete peace of mind, whether on an untuned factory car or equally for those that wish to increase the power and torque output without ever having to worry again; MMR have engineered the most comprehensive solution on the market and at one of the most compelling price points.

OE Multi-Piece Crank Hub (L) compared to MMR Single Piece Crank Hub (R) 

The crank hub is machined from billet EN36 steel that's been heat-treated with a 0.75mm case hardening, making it incredibly strong and durable. The one-piece design ensures the friction plates can no longer slip and with a new crank bolt tightened appropriately, this alone delivers the transformational improvement in reliability versus the OE version.

Single-Piece Crank Hub (L) with Capture Plate (R)

As MMR Performance offers two versions of the Single-Piece Crank Hub, which is best for you, pinned or unpinned?  For most standard to Stage 1 tuned S55 & N55 engines, this unpinned MMR Single-Piece Crank Hub is more than sufficient. Installation is more straightforward as the end of the crankshaft does not need to be precision drilled to mount the four locating dowels. However, for high power/torque engines tuned beyond this level, we recommend the upgraded pinned version of the Crank Hub that incorporates the 4-pin dowel drive mounting for the ultimate engine security. The 4-pin version is part number MMR20-1004.

Finally. alongside the Crank Hub, the optional MMR Capture Plate ensures that owners have complete peace of mind. 

This 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. Please select from the product option below at point of ordering to include a Capture Plate with your order.

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

FITMENT DETAILS

Please check the product title, part number and fitment notes before ordering. If you are unsure, contact us with your registration or VIN and we will confirm compatibility.

Warranty: Products are supplied with the applicable manufacturer warranty.

Shipping: We offer UK and worldwide shipping. Supplier-stock delivery estimates are shown above.

Returns: Eligible unused items can be returned within 14 days in accordance with our returns policy.

Klarna payment options are available at checkout where eligible.