High-output BMW engines are unforgiving when tolerances slip--and few failures are as destructive as a crank bolt backing out. The VAC Motorsports Crank Bolt Lock is designed to add a critical mechanical safeguard to the front of your engine, reducing the risk of crank bolt loosening under high load, aggressive driving, or track use.
Rather than relying solely on friction or torque retention, this system mechanically secures the crank bolt in place, helping maintain proper clamping force at the crank hub. The result is improved reliability during hard launches, repeated high-RPM operation, and extended performance use--whether on the street or at the track.
While no bolt-lock solution can fully prevent crank hub rotation on its own, securing the crank bolt significantly reduces one of the primary contributors to hub slip. For maximum protection, VAC Motorsports strongly recommends pairing this crank bolt lock with a pinned or upgraded crank hub solution.
Designed With Serviceability in Mind
Unlike many lock-style solutions that complicate routine engine work, this design incorporates a machined 32mm hex, allowing the engine to be rotated by hand without removing the lock. That means valve work, timing checks, or service procedures can be performed cleanly and efficiently--without added disassembly.
To further improve consistency and ease of installation, the system uses a single precision steel locking washer rather than multiple small washers. This ensures uniform load distribution across the hub face and simplifies installation while maintaining secure retention.
Fitment & Application Notes
⚠️ Important: Some N54 engines are equipped with an 8-bolt crank hub. Physical inspection is required to confirm correct fitment before ordering.
Key Features
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Designed and Manufactured in the USA
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Available in 6-bolt and 8-bolt configurations
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Integrated 32mm hex for engine rotation and service access
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CNC-machined billet 6061 aluminum body
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Stealth black anodized finish
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Single-piece steel locking washer for optimal load distribution
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High-strength 12.9-grade alloy steel mounting hardware (silver or black zinc)
Installation Notes
The VAC Motorsports Crank Bolt Lock is designed to bolt directly to the factory crank hub/pulley assembly. In rare cases, slight crank bolt stretch may be present. Always verify that the supplied fasteners thread smoothly into the hub before final assembly.