Splines vs. Pins: Why the VTT™ Spline Lock Crank Hub Is a Necessity

The crank hub plays a critical role in every BMW engine, keeping the crankshaft and timing system in perfect alignment. Unfortunately, the factory design used in the S55 platform has a reputation for failure, especially in performance applications. Vargas Turbocharger Technologies developed a precision-engineered S55 engine crank hub upgrade that solves this problem and delivers long-term reliability. Here’s why this spline lock design is essential for anyone looking to make more power or improve track results.

Why S55 Pin Crank Hubs Fail

Under heavy load, rapid gear changes, or higher RPM operation, the factory S55 crank hub can slip. When it happens, timing is thrown off, power drops, and in the worst cases, engine damage can occur. The stock hub relies on friction discs and a pin-based system that simply can’t withstand the stress created by higher horsepower and aggressive driving.

To eliminate this weak point, VTT™ designed a complete BMW crank hub fix that replaces the flawed design with a stronger, spline-based locking system.

How VTT™ Spline Locks Are Different

The VTT™ spline lock S55 crank hub uses an interference fit that presses into the crank snout and forms a full mechanical bond. During installation, the splines create matching grooves in the crankshaft, providing 360-degree engagement and preventing any chance of slippage.

This precision fit means no drilling, pinning, or welding is required, making installation straightforward and secure. The design is also fully reversible, allowing for easy removal if needed. For an additional layer of protection, pairing the spline lock crank hub with the VTT™ Crank Bolt Capture provides complete crankshaft security under extreme conditions.

Why Upgrading Is a Necessity

Whether your BMW is a weekend warrior or a dedicated track build, upgrading to a spline lock crank hub is one of the most important reliability modifications you can make. The S55 platform in particular benefits from this upgrade because of its known crank hub weaknesses under high torque and RPM.

VTT™ tested its spline lock crank hub design under extreme stress, so much so that the test rig failed before the crank hub did. That level of durability ensures you can push your engine with confidence. If you want consistent performance, improved safety, and a worry-free driving experience, this upgrade isn’t optional; it’s essential.

Get a spline lock crank hub for your S55 engine from VTT™ at vargasturbo.com