ACL Race Series main bearings for Mitsubishi FTO, Mirage, Carisma... (4G9*)
Fits
Mitsubishi
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- Collection at our shopCartagena, Spain
ACL Race Series main bearing set for Mitsubishi FTO, Mirage, Carisma... (4G9*), part number 5M8037H. These support the crankshaft in the block and, in a tuned engine, they are responsible for ensuring that oil reaches the entire crankshaft properly.
Internally, they feature three layers on a high-strength steel base: a copper-lead-tin lining, a thin nickel barrier, and a lead-tin-copper sliding layer, which is the part that works against the crankshaft.
The upper shells have a full 180° oil groove, while the lower shells have a partial groove to avoid cutting off oil flow to the connecting rods, with a tapered groove end to prevent pressure spikes. Compared to a stock bearing, the Race range has more housing crush, which improves retention and heat transfer, as well as greater eccentricity to support the oil film when the engine is revving high.
In standard size, ACL specifies this for a crankshaft journal of 49.982 to 50.000 mm, and for that diameter, it recommends an oil clearance of about 0.053 to 0.063 mm. If the crankshaft has been ground, the measurement changes.
They do not have the silver-tin final coating of standard bearings, so their dark color—a mix of brown, black, and bluish—is the factory finish and does not indicate any defect. ACL advises against polishing the surface of the bearings to adjust the clearance; if more is needed, they should be combined with the HX version, which provides an additional 0.025 mm of clearance.
If the crankshaft has been ground or you are unsure of the required size, write to us with your engine code before ordering.