Engine Crankshaft Main Bearing Set +0.50mm BMW 240i 340i 440i 540i X5 X6 B58

The main bearings are the backbone of the BMW B58/S58 engine's rotating assembly, responsible for supporting the crankshaft under extreme turbo boost and high-RPM stress. When the crankshaft journals exhibit deep scoring or significant wear, they must be professionally machined to a second undersize. This +0.50mm (+0.020in) oversized main bearing set is engineered specifically to compensate for the reduced journal diameter, restoring the critical oil film clearance necessary for high-performance operation. Manufactured with advanced multi-layer alloys, these bearings ensure maximum fatigue resistance and stable oil pressure, protecting the engine block and crankshaft from catastrophic failure during a complete bottom-end overhaul.