The ACL Race Series Main Bearing (Part #5M1581H-.25) is a precision-engineered main bearing set designed for high-performance engine applications. These bearings support the crankshaft within the engine block, enabling smooth rotation while handling significant radial and thrust loads. Engineered for optimal oil film retention and wear resistance, ensuring consistent engine performance. Manufactured to OE specifications for direct replacement applications. Engineered with strict quality control standards to ensure consistent performance and reliable engine operation.

Applicable to:
- BMW M3 E90 All (S65B40)
- BMW 3 (E90) M3 (S65B40A)
- BMW 3 coupe (E92) M3 (S65B40A)
- BMW 3 Convertible (E93) M3 (S65B40A)