MMX BMW S55 & N55 Single Piece Crank Hub Upgrade

The MMX Single Piece Crank Hub Upgrade is the ultimate solution to the well-documented crank hub failures affecting BMW’s S55 and N55 engines. Designed with a 4-pin dowelled single-piece design, this upgrade eliminates the risk of the factory three-piece hub slipping – a known cause of catastrophic engine failure in M2, M3, M4, and N55-powered models.

CNC-machined in the UK from heat-treated billet EN36 steel with 0.75mm case hardening, the hub offers exceptional strength and durability. Four aerospace-grade precision dowels mechanically lock the hub to the crankshaft, preventing any possibility of movement. The kit also includes a brand new OE crank bolt for complete security.

To simplify installation, the MMX kit comes complete with a bolt-on drilling guide jig, location bolt, and HSS rolled drill bit – ensuring professional fitment is accurate, safe, and straightforward. For those seeking the ultimate level of security, the hub is also available with an optional capture plate.

Key Features:

• Part Number: MMR20-1004

• Single-piece design – eliminates OE crank hub slip issues

• 4 aerospace-grade precision dowels for a secure mechanical lock

• Machined from heat-treated billet EN36 steel with case hardening

• Supplied with a new OE crank bolt

• Includes full installation jig, drilling guide, and HSS drill bit

• Optional capture plate for additional protection

• Designed and manufactured in the UK

• The ultimate reliability upgrade for BMW S55 and N55 engines

Compatibility:

• BMW 1 Series (F20/F21) – M135i (N55)

• BMW 2 Series (F22/F23, F87) – M235i, OG M2 (N55), M2 Competition (S55)

• BMW 3 Series (F30/F31, F80) – 335i (N55), M3 (S55)

• BMW 4 Series (F32/F33, F82) – 435i (N55), M4 (S55)

• Model Years: 2011–2021

Protect your BMW from crank hub failure with the MMX S55 & N55 Single Piece Crank Hub Upgrade – precision-engineered for strength, durability, and complete peace of mind.

Unless explicitly stated otherwise, all products sold by R44 Performance Limited are designated RACE ONLY and are solely for competition or off-road use limited to racing formally sanctioned by a recognized racing organization. Any other use, including recreational off-road use, may violate local, state, and Federal laws. R44 Performance Limited does not implicitly or explicitly confirm the legality of using any products it sells on public roads; that is entirely the responsibility of the consumer.

It is the responsibility of the customer to check with all federal, state local and environmental laws before ordering and installing a product. R44 Performance Limited is not responsible for any fees, fines or costs that a customer may incur as a result of failing to check with federal, state, local or environmental laws before ordering and installing a product.

We get a large number of custom orders and requests everyday, so as a result it is not always possible for us to keep every item in stock at all times in our warehouse. If you require the item urgently please contact our sales team here to check the stock before you make your purchase.

We totally understand if you're not certain a part will be compatible with your car, so we highly recommend contacting us here with your query. Our friendly sales team will then be in touch to confirm if this part is the correct part you are looking for.

All in stock products ship the same day if ordered before 2pm GMT

For out of stock items we will contact you with an estimated wait time if not otherwise specified above.

We offer worldwide shipping on all products. If upon receiving your product you wish to return; we offer a 30-day returns policy. For our in-depth returns information please follow the link. "R44 Returns Policy

All of our products come with a standard warranty of 1-3 years. This is dependant on the type of product however. For more details please see our warranty page here.