Tri-metal main bearings twin tang BMW M20 M50 M52 M54 S50 S54

The tri-metal main bearing sets from ACL RACE and KING RACING for the M20, M50, M52, S50 and S54 engines are made up of 14 bearing shells.

Below (click on the image) you will find the tri-metal big end bearings for BMW M20, M50, M52, S50 and S54B32 engines:

M20, M50, M52	S54B32

S50B30	S50B32

Technical specification

• Crankshaft main journal diameter (min/max): 59.971 / 59.990mm
• Main bearing housing bore (min/max): 65.000 / 65.019mm
• Maximum thickness: 2.490mm
• Oversizes: standard, standard with HX clearance, +0.025, +0.25 or +0.5mm
• Anti-friction coating: none
• Part numbers: 7M1532, 7M1532H-STD, 7M1532HX-STD, 7M1532H-.025, 7M1532H-.25, 7M1532H-.50

ACL Race Series tri-metal bearings are manufactured to tight tolerances. CNC machining is carried out to within microns, after which the diameters, thickness and width of every ACL Race Series tri-metal bearing are checked on metrology equipment. ACL Race Series bearings therefore deliver a reliable and consistent fit in your performance engine. ACL Race Series tri-metal bearings are in fact built up from four layers:

• SAE1010 steel on the outside
• 0.3mm copper alloy
• 0.0001mm nickel
• copper alloy from 0.013 to 0.018mm

This choice of materials combined with the manufacturing processes makes ACL Race Series tri-metal bearings more resistant to increases in power, torque and engine speed. The compressive strength of ACL Race Series tri-metal bearings brings reliability to your engine even with heavily boosted turbocharged or supercharged builds, or high-revving competition engines.

Technical specification

• Crankshaft main journal diameter (min/max): 59.97 / 59.99mm
• Main bearing housing bore (min/max): 65.00 / 65.02mm
• Maximum thickness: 2.494mm
• Oversizes: standard, standard with HX clearance, +0.026, +0.25 or +0.5mm
• Anti-friction coating: with or without
• Part numbers: MB7039, MB7039XP, MB7039XP STDX, MB7039XP.026, MB7039XP0.25, MB7039XP0.5, MB7039XPC, MB7039XPC STDX, MB7039XPC.026, MB7039XPC0.25, MB7039XPC0.5

Since 1960 KING RACING has been designing and manufacturing high performance, high quality bearings. Beyond its high performance production machinery, King Racing relies on simulation software to analyse the thermodynamics, dynamics and elasto-hydrodynamics of its bearings. KING RACING tri-metal bearings are produced in pMax Black, a tri-metal alloy 24% stronger than any existing tri-metal bearing.

KING RACING bearings are built up from three to four layers, depending on the application:

Outer layer: steel Intermediate layer: lead bronze Inner layer: bearing metal with a high copper content Anti-friction coating containing lubricant and ceramic additives