The Ultimate Fix for S55 & N55 Crank Hub Failure – Proven Reliability

The factory three-piece crank hub used on the S55 & N55 engines (F80 M3, F82/F83 M4, F87 M2 etc.) is a well-known weak point. Under load, the OE hub’s friction plates can slip, causing the timing to jump. When this happens, piston-to-valve contact is highly likely — often resulting in catastrophic engine damage and a repair bill into the thousands.

The MMX Performance One-Piece Billet Crank Hub eliminates this risk completely. Whether your engine is stock or running increased power and torque, this is the most complete and robust crank hub solution available.

Why Upgrade?

OE Hub Failure — A Known S55/N55 Weakness

The standard BMW crank hub uses a multi-piece friction design. Under higher torque (even from factory), the friction plates can slip, resulting in:

• Timing jump

• Potential piston-to-valve contact

• Total engine failure

BMW’s only solution? Replace the entire assembly — and often deny warranty on modified vehicles.

One-Piece Billet Hub = No More Slip

MMX’s redesigned hub is a single, solid billet EN36 steel component, heat-treated and case-hardened. There are no friction plates to slip, meaning the hub and timing gear remain permanently locked together.

Key Features

• One-piece billet EN36 steel hub – case hardened (0.75mm surface)

• Eliminates slip from friction-plate design on OE hub

• Straightforward install (no drilling for dowels required on unpinned version)

• Optional Capture Plate prevents crank bolt loosening

• Engine-safe solution for stock & tuned cars

• Suitable for road, track and high-power builds

Capture Plate 

The Capture Plate is bolted over the crank bolt head and physically prevents bolt loosening from vibration or harmonics.

Benefits:

• Locks the crank bolt in place – zero chance of it backing out

• Ideal for high-RPM track or drift environments

• Adds a second layer of security over the one-piece hub

Pinned vs Unpinned Version — Which Should You Choose?

MMX offers two versions of the crank hub:

For most customers, the unpinned version is more than sufficient.

Installation & Torque Specs

• Follows BMW OE procedure

• No special tools required (for unpinned hub)

• Crank bolt torque: 100 Nm + 270° rotation (S55/N55)

Professional installation recommended.

Compatibility

BMW S55 & N55 Engines:

• F87 M2 / M2 Competition (N55/S55)

• F80 M3

• F82 / F83 M4

• Also fits other BMW models using N55 engines