AROS GROUP LTD
MMX 4-Pin One-Piece Crank Hub Upgrade, Keyed Pinned Hub Conversion for BMW S55 & N55 Engines (M2 Competition, M3, M4; selected 35i)
MMX 4-Pin One-Piece Crank Hub Upgrade, Keyed Pinned Hub Conversion for BMW S55 & N55 Engines (M2 Competition, M3, M4; selected 35i)
Heads-up on cancellations & returns: if you cancel an order or return an item, you won't get back 100% of what you paid. We apply a 10% restocking fee, the outbound shipping is non-refundable, and we have to pass on Shopify / PayPal payment processing fees; these aren't returned to us when we refund you. International orders also lose on exchange-rate spread in both directions. If the original packaging is damaged or missing, a reboxing charge applies. For international orders specifically, if you refuse to pay our shipping invoice or supply a prepaid label after placing the order, the same deductions apply. We're upfront about this — please be sure of your purchase before ordering.
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Stop timing slip and protect your BMW’s heart
The factory multi-piece friction hub used on these turbocharged straight-six engines can rotate under shock loads, shifting cam timing and risking serious top-end damage. This four-pin, single-piece crankshaft hub upgrade delivers a positive mechanical drive between the crank and timing gear, so your mapping stays where it should, pull after pull. For belt-and-braces security, add the optional Capture Plate to lock everything down.
Why this upgrade is essential
- Four-pin positive location prevents rotational movement under high torque and rapid shifts
- One-piece design eliminates the known slip associated with the OE friction-plate arrangement
- Protects against costly valve-to-piston contact by keeping timing rock steady
- Perfect preventative mod for tuned cars, hybrid turbos, track days and hard road use
- Optional Capture Plate available for ultimate crank bolt security
- Engine compatibility: BMW S55 and N55 platforms, including M2 Competition, M3, M4 and selected 35i models
Real-world results
We have installed this four-pin hub on numerous customer builds at MJ Modifications. Feedback has been consistently positive, with owners praising the peace of mind, reliability under aggressive driving and the confidence to push harder after a remap. It is our go-to fix for timing slip concerns on these engines.
Who is it for
Ideal for anyone running increased boost, launch control, fast road, drag or circuit work, as well as owners who simply want to safeguard their investment with a proven reliability upgrade.
Installation
Professional fitting is strongly recommended. For a hassle-free service, book your installation with MJ Modifications in Warwickshire. Request a quote at info@mjmodifications.co.uk.
Good to know
- Single-piece, four-pin hub design for maximum stability
- Capture Plate available separately for added security on high-output applications
- A proven preventative measure against timing drift on S55 and N55 engines
Search-friendly terms
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