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BMW I S55 I N55


Why fit?

Installation of the MMR Performance One Piece Crank Hub and Capture Plate Kit fully addresses the well-known crank hub issues on BMW’s S55 & N55 engines in M2C, M3 and M4, and M135i/M235i models. By securely preventing the OE unit’s friction plate from slipping, catastrophic piston-to-valve contact is prevented once and for all.

Benefits of fitting?

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 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 one-piece Crank Hub together with our 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 significantly 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.

The MMR Performance one-piece crank hub is machined from billet EN36 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.

Finally, the optional MMR Capture Plate ensures that owners have complete peace of mind. The 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 I N55


2011 - 2020

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Pinned vs Unpinned:

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.

Whether Pinned or Unpinned, the MMR Crank Hub kit can be ordered in two formats. The Single-Piece Crank Hub can be selected on its own, or for best protection, choose the Crank Hub together with our billet Capture Plate. Our recommendation is always that if you're replacing the crank hub, you may as well add in the Capture Plate for the best possible future protection.

Please select your required option when ordering.

Fitting note:

Careful design has allowed us to develop a solution that's easy to install compared to some other products as there's no drilling or modification required to the OE crankshaft, which saves you time and ultimately money, too.

Installation of a replacement Crank Hub and/or Capture Plate is a significant task, and should always be left to professional technicians.

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

Note that if your factory Crank Hub has already shown any signs of slippage, you will have no choice but to replace it - once slipped there is no repair possible.

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How we develop.

Every MMR Performance upgrade is developed and tested here in the UK by our expert engineering team of BMW enthusiasts.

Nothing gets the MMR logo until we've thoroughly proven it on road, track and dyno.

That's the MMR Performance difference.


How to buy?

Our network of expert MMR Performance dealers can supply the full range, together with product guidance and advice, plus often an experience fitting service.


If you haven't got a MMR Performance Partner Dealer close to you, don't worry! Remember you can buy direct from our MMR Performance webshop. Click here to browse and shop online, for worldwide despatch.


Prefer to buy online?

You can buy direct from our MMR Performance webshop. Click here to browse and shop online, for worldwide despatch.

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