3XL Racing Two-Piece 4-Pin Crank Hub – BMW S55

The 3XL Racing Two-Piece 4-Pin Crank Hub is engineered to eliminate crank hub slip while maintaining installation flexibility for high-performance BMW S55 engines.

By combining a precision two-piece architecture with a mechanically locked 4-pin interface, this system reduces tolerance stack-up during installation while maintaining high torque capacity for modified and high-boost S55 builds.

Key Features

• Two-piece crank hub design for easier alignment
• 4-pin mechanical anti-slip locking system
• Billet 4340 high-strength alloy steel construction
• Nitro-conditioned surface treatment (HRC 55–58)
• Precision CNC machined for exact fitment
• Capture plate with toothed self-locking bolts included
• Precision drill jig included for accurate pin placement
• Designed for high-horsepower S55 builds

What Problem Does This Solve?

The factory BMW S55 crank hub relies primarily on friction and bolt preload. Under increased torque loads, this may result in:

• Crank hub rotation
• Timing slip
• Crank bolt loosening due to fatigue
• Engine timing failure

The 3XL Racing two-piece solution replaces friction-only retention with a mechanically pinned crankshaft interface, preventing rotational slip.

Engineering Design

Two-Piece Construction

• Improves installation flexibility
• Reduces alignment complexity
• Maintains precise sprocket positioning
• Enhances serviceability compared to one-piece hubs

4-Pin Anti-Slip Design

• Balanced rotational load distribution
• Redundant locking structure
• Precision dowel pin interface between crankshaft and hub

Mechanical Locking System

• Four hardened dowel pins lock hub to crankshaft
• Capture plate prevents crank bolt rotation
• Toothed self-locking hardware ensures retention

Materials & Manufacturing

• Material: 4340 High-Strength Alloy Steel
• Manufacturing: Precision CNC Machined
• Surface Treatment: Nitro Conditioning
• Surface Hardness: HRC 55–58

Kit Includes

• Two-piece crank hub assembly
• Hardened dowel pins
• Precision drill jig
• Capture plate
• Crank bolt
• Installation hardware

Installation Information

• Engine removal required: No
• Professional installation: Recommended
• Special tools required: Crankshaft locking tool
• Estimated install time: 18–24 hours

Torque Specifications

• Crank bolt: 100Nm + 270°
• Capture plate bolts: 25 ft-lbs

Designed For

• Street performance builds
• Track use
• High boost applications
• Built engines
• Up to 700 HP setups

Compared to OEM

• Mechanical 4-pin locking system
• Eliminates friction-only retention
• Improved timing stability
• Reduced crank hub slip risk

Compared to One-Piece Designs

• Easier installation alignment
• Improved serviceability
• Reduced installation complexity
• Same locking strength with added flexibility

Compared to Friction-Based Solutions

• No relative rotation possible
• Higher torque capacity
• Eliminates spun crank hub failure mode

Testing & Validation

• 50,000 km test vehicle mileage
• Tear-down inspection completed
• No abnormal wear observed
• Ongoing durability testing

Vehicle Fitment

• BMW F80 M3 (S55)
• BMW F82 M4 (S55)
• BMW F83 M4 (S55)
• BMW F87 M2 Competition (S55)

Summary

The 3XL Racing Two-Piece 4-Pin Crank Hub combines installation flexibility with a mechanically locked anti-slip design, making it ideal for modified S55 engines requiring reliable timing retention and high torque capability.