The Infamous S55 Crank Hub
The BMW S55 engine is a high-performance power plant used in the BMW M3 and M4 models. However, it has been plagued by a significant issue with the crank hub. This issue has caused a number of engine failures but is it really as much as everyone thinks? We asked users of all tune levels in our F80/F82 Facebook group and found that out of 136 replies, only 8 owners had failures with the stock hub.
What is the crank hub? The crank hub is a small component that connects the engine’s crankshaft to the oil pump drive. It is designed to ensure that the oil pump rotates at the same speed as the engine. Unfortunately, the S55 crank hub is not up to the task, and it can fail suddenly and catastrophically. When the crank hub fails, the oil pump stops turning, leading to a sudden loss of oil pressure. Without proper lubrication, the engine can quickly overheat and suffer severe damage.
There are a few factors that contribute to the failure of the S55 crank hub. First, the crank hub is made of a relatively soft material, which makes it more prone to wear and tear. Second, the design of the hub places a lot of stress on a small area, leading to premature wear and tear. Finally, the engine’s high power output and high RPMs place additional stress on the crank hub, increasing the risk of failure.
To address the issue, third party companies have released an upgraded crank hub that uses a keyed design to reduce the stress on the hub. Many enthusiasts have opted to upgrade to this improved design to prevent potential engine failures. However, the upgrade can be costly, and it does not guarantee that the issue will not occur again in the future.
In conclusion, the S55 crank hub issue is a very common topic among F8X enthusiasts. The sudden failure of the crank hub can lead to significant engine damage, leaving owners with expensive repair bills. Use as much data as you can to determine if it makes sense in your situation to upgrade the crank hub.
