ACL Race Series connecting rod bearings for BMW S14 (M3 E30)
Fits
BMW
Nissan
E30S14- Shipping in 24-48 hSubject to availability
- 14 days to returnUnfitted and in its original packaging
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- Collection at our shopCartagena, Spain
These ACL Race Series connecting rod bearings, part number 4B1568H, are for the BMW S14 (M3 E30). They are the go-to choice when opening up an engine for tuning.
Inside, they feature three layers on a high-strength steel backing: a copper-lead-tin lining, a thin nickel barrier, and a lead-tin-copper sliding layer, which is the one that works against the crankshaft. In connecting rod bearings, the surface layer is thinner to better withstand fatigue.
ACL manufactures them with more "crush" than a standard bearing, so they remain securely seated and dissipate heat better, as well as more eccentricity, which helps them maintain the oil film when the housing deforms at high RPM.
In standard size, ACL specifies them for a crankpin of 47.975 to 47.991 mm, with a bearing width of 20.0 mm. For that diameter, they recommend an oil clearance of about 0.051 to 0.061 mm, measured with a micrometer and bore gauge. If the crankshaft has been reground, the measurement changes.
They do not have the silver tin final coating 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, they are combined with the HX version, which provides an additional 0.025 mm of clearance.
Not sure if your crankshaft is standard size? Write to us with your engine code and we will help you choose.