ACL Bearings 5M8309H-STD Race Series Main Bearing Set Standard Size

The ACL Race Series 5M8309H-STD main bearing set represents the perfect combination of advanced metallurgy, precision engineering, and decades of motorsport experience. Designed specifically for Subaru EJ20, EJ22, and EJ25 engines with thrust bearing in the #5 position, this standard size bearing set delivers the durability and performance that high-horsepower builds demand.

Advanced Tri-Metal Construction:

Each bearing features multi-layered tri-metal copper alloy construction with a hardened steel backing, engineered to withstand extreme RPM conditions, high stress loads, and elevated temperatures. The high-strength overlay plate with reduced thickness provides improved fatigue properties and excellent seizure resistance, while the softer bearing material protects your crankshaft and engine block from premature wear.

Performance-Engineered Features:

• 3/4 groove design optimizes bearing load carrying surface area and maximizes oil flow to connecting rod bearings
• Increased crush and elimination of flash plating for improved bearing retention and heat transfer
• Enhanced eccentricity compensates for bore distortion at high RPM and assists in hydrodynamic oil film formation
• Enlarged inner diameter chamfers accommodate large fillet radius on performance crankshafts
• Manufactured to exact tolerances ensuring reliable fit and consistent clearances
• Tight, consistent wall tolerances for optimal bearing seating

This complete set of 5 main bearings is manufactured with ISO-certified processes and represents over 70 years of ACL's bearing expertise. Trusted by professional engine builders and motorsport teams worldwide, ACL Race Series bearings deliver proven reliability in drag racing, drifting, rally, and road racing applications.