Crank Hub Replacement S55 and N55
Another unfortunate engineering oversight by the experts in Germany has been the non- keyed or non-pinned crank hub design of the N55 and S55 Line of engines . Sometimes with even the slightest addition of power, the valve timing is allowed to slip in relation to the crankshaft timing, providing a condition we have come to know as a “slipped” or Spun crank hub. Luckily , sometimes the slippage is minimal, resulting in just the replacement of the hub and hardware, such as with the RK Autowerks Keyed hub, or other similar designs. Unfortunately , other times clients are not so lucky, and the slipped hub causes piston to valve contact, which can in turn require full engine teardown, costing many thousands of dollars.
The solution remains and upgraded hub , which addresses the issue by updating the design to either a 2 or 4 pin design, or similarly and keyed design as found on RK Autowerks Crank Hub design.
Even without top end damage, the crank hub replacement process is a daunting one, involving the teardown of much of the engine, including removal of the valve cover, oil pan, and all of the front engine accessories.
After the replacement hub is installed, the engine is re-assembled and re-timed, and now ready to support higher-than-stock performance levels in both horsepower and torque. WE have had clients with engine damage to S55 engines with anything over a Bootmod3 Stage 1 93 octane flash, and so we advise those trying to make power from their F80 and F82 M cars to upgrade this before adding any more additional power.
You can purchase the RK Autowerks Billet Crank Hub in our store!