The Achilles heel of BMW’s S55 (F8X M2 Competition/M3/M4)  and N55 engines (135i/M135i/M235i/M2/335i/435i etc) is the crank hub. From factory, the crank hub and associated timing/pump drive sprockets are all separate pieces only held together with friction applied by a large central bolt. With aggressive driving and/or tuned engines with increased torque outputs, the timing chain sprocket can slip on the hub, or the hub itself can slip causing running problems, engine damage or catastrophic engine failure.

Vargas Turbo Technologies pioneered a fix for it. The timing sprocket is now a single piece with the hub, and the hub uses VTT’s Spline Lock technology to positively lock the hub to the crank. As tested on VTT’s own 900whp, 8000rpm race car.

Unlike rival products, no drilling of the crankshaft is required. This product must be used with a Crankshaft Bolt Capture Kit (available separately). VTT “Spline Lock” Crank hubs are CNC manufactured from 440C tool Steel with a Rockwell rating of HRC60 for the ultimate in durability, and toughness.

Installation instructions here.