S55 engine crank hub upgrade service

One of our signature services offered to enthusiast owners of M2, M3, and M4 BMW’s with the S55 Crank Hub Upgrade engine. One potential weakness within this engine exists within the crankshaft and its interface between it and the timing chain hub which connects the cylinder head valvetrain to the crankshaft. For most stock engines, the factory design is sufficient and only a few failures have been observed. However, for those adding horsepower through modifications to tuning, intake, exhaust, larger turbos, etc… We see failures with more frequency.

Failure occurs when the “friction” interface between the crankshaft and the timing chain sprocket slips, resulting in loss of camshaft timing and valvetrain impact with pistons. This causes costly engine failure. Numerous companies have produces “pinned” type sprocket hubs which “bullet-proof” this area by no longer relying on a friction interface between the parts.

A very involved job, completion of this upgrade task must always require disassembling the top end and bottom end of the engine, and removal of all front bodywork and coolers. Shopping for a facility that is trusted for such a task can be difficult. Factors must be considered- experience with this particular job, understanding of the problem and the remedy, plus individual technician cleanliness and attention to detail. A poor quality job or use of sub-standard parts can result in a car that suffers from occasional gremlins and follow-up shop visits, to all-out engine failure.

Beware of low cost quotes for this task. There are many aftermarket crank-hub “locking” products advertised with seemingly simple installations and reduced up-front costs we see range anywhere from $2000-$4000. While these products may be a viable option for more “DIY” minded owners with limited resources, the final product produced is (in our experience) not as robust as a true factory-grade execution with a drilled crankshaft and pinned hub. Shops may utilize those more basic approaches combined with other shortcuts like omitting other parts and not removing the subframe and oil pan, in an effort to advertise a very appealing estimate for those not familiar with the caveats.

Mporium has performed many of these S55 crank hub jobs across all chassis variants. As one of our most commonly requested jobs for the S55 crank hub upgrade, we stock parts on hand to be able to perform this task quickly and efficiently. Once the crank-hub fix has been performed, owners can feel more free to unleash additional boost having bullet-proofed this area.

Due to variations between cars, mileages, condition, etc., this is approached as a “base” package which covers the mandatory items for a satisfactory execution of the upgrade. As such an invasive task, there is much potential for additional “while you’re in there” parts or labor. Higher mileage S55 engines will require a few additional parts that we’ve over time determined are needed to complete the job to our standards. We will make recommendations based on your needs to establish the ideal outcome. We employ a 4-pin S55 Crank Hub Upgrade, exclusively, such as the component from fellow Texas company, RK Autowerks. It takes more time and effort but produces a more bullet-proof product. The base job always includes the upgraded crank-hub, associated sealings and gaskets, plus required new hardware, chain rail parts, tensioners, etc. It includes new oil and filter. This job re-places both the valve cover gaskets plus the oil pan gaskets, therefore any pre-existing leaks at these locations are resolved during the job. As one of our Signature Services, pricing considers combined margins for parts and labor to provide an overall lower final cost for the customer as a packaged offering. We do not perform this task with customer provided parts.