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VAC Motorsports

Crank Hub 4-Pin S55 Engine

$654.47

SKU: 21bmw170

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Overview

The VAC Motorsport Crank Hub is a CNC-machined replacement part designed to fix a common failure point in tuned S55 engines. This 4-pin design mechanically secures the crank hub to the crank nose, preventing independent spinning of the valve timing and oil pump chains. The assembly is reduced to two pieces, ensuring the timing sprocket stays synchronized with the crank when the bolt is properly tightened.
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A common issue with tuned S55 engines is crank hub failure, which can lead to severe engine damage. The VAC Motorsport 4-Pin Crank Hub is engineered to resolve this problem. This hub is CNC machined for greater precision than OEM, featuring a 4-pin design that mechanically locks it to the crank nose. This system prevents the valve timing and oil pump chains from rotating independently of the crankshaft. The assembly process has been simplified from three components to two. As long as the crankshaft bolt is correctly torqued, the timing sprocket will remain perfectly synchronized with the crank. This ensures reliable engine operation, especially under high-boost conditions. The kit includes the crank hub, a keyed oil pump gear, a genuine BMW crankshaft bolt, a drill bit, a drill guide, and a VAC Crank Seal Guard.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

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Specifications

BrandVAC Motorsports
Part Number21bmw170
CategoryTools
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Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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