{"product_id":"acl-trimetal-reinforced-main-bearings-mitsubishi-4g63-4g64-83-92","title":"ACL Race Series main bearings for Mitsubishi 4G63, 4G64 (83-92)","description":"\u003cp\u003eACL Race Series main bearing set for Mitsubishi 4G63, 4G64 (83-92), part number 5M1144H. These support the crankshaft in the block and, in a tuned engine, they are responsible for ensuring oil reaches the entire crankshaft properly.\u003c\/p\u003e\u003cp\u003eThe structure is tri-metal, with a steel backing, copper-lead-tin lining, nickel barrier, and a soft overlay that conforms and prevents seizing even under very high loads.\u003c\/p\u003e\u003cp\u003eThe upper bearings feature a full 180° oil groove, while the lower bearings have a partial groove to avoid restricting oil flow to the connecting rods; the end of the groove is tapered to prevent pressure spikes. Compared to stock bearings, the Race range has higher crush for better retention and heat transfer, and increased eccentricity to promote an oil film at high engine speeds.\u003c\/p\u003e\u003cp\u003eIn standard size, ACL specifies this for a crankshaft journal diameter of 56.980 to 57.000 mm, and recommends an oil clearance of approximately 0.059 to 0.070 mm for that diameter. If the crankshaft has been reground, the measurement changes.\u003c\/p\u003e\u003cp\u003eThey do not have the final silver tin plating of standard bearings, so their dark color—ranging from brown and black to bluish—is the factory finish and does not indicate any defect. ACL advises against polishing the bearing surface to adjust clearance; if more is needed, combine them with the HX version, which provides an additional 0.025 mm of clearance.\u003c\/p\u003e\u003cp\u003eIf the crankshaft has been reground or you are unsure of the required size, please contact us with your engine code before ordering.\u003c\/p\u003e","brand":"ACL","offers":[{"title":"Default Title","offer_id":50813086499150,"sku":"ACL-5M1144H\/66","price":151.95,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0816\/7329\/0062\/files\/acl-main-bearings_2f2298c4-71c9-42b9-8858-10032dd0fe26.jpg?v=1735903761","url":"https:\/\/driftandgrip.com\/en\/products\/acl-trimetal-reinforced-main-bearings-mitsubishi-4g63-4g64-83-92","provider":"Drift \u0026 Grip","version":"1.0","type":"link"}