ACL Bearings 5M1237H-.25 Race Series Tri-Metal Main Bearings

ACL Race Series Main Bearings deliver high-performance engine protection through advanced tri-metal construction and race-proven engineering. These precision-machined bearings feature both upper and lower shells with a .25mm undersize specification, designed specifically for rebuilt or undersize crankshafts in high-RPM racing applications.

Race Series Performance Features:

• High-strength overlay plate with optimized thickness for superior fatigue resistance under extreme loads
• Hardened steel backing on all bearings to maximize support of the bearing lining and improve retention in the housing
• Increased crush for enhanced bearing retention and stability during high-RPM operation
• No flash plating on bearing backs to maximize heat transfer and improve grip between bearing and housing
• Increased eccentricity to compensate for bore distortion at high RPM and promote optimal hydrodynamic oil film formation
• 3/4 groove design on main bearings to optimize load-carrying surface area while maintaining proper oil flow to connecting rod bearings
• Tight wall tolerances for consistent bearing clearances and reliable performance
• Enlarged ID chamfers on bearing edges to accommodate large fillet radii found on performance crankshafts

ACL's tri-metal construction combines a durable steel back, high-performance lining material, and protective overlay to deliver the strength and reliability required for racing and high-performance street applications. Each bearing set includes both upper and lower shells for complete main bearing replacement.