BMW Connecting Rod Bearing Set - ACL 4B1568H-STD

Questions about the appearance of the ACL RACE Series performance engine bearings are quite common, as this series of trimetal copper lead bearings have a very different appearance to regular after market “ACL Duraglide” trimetal bearings, which have a light silver/ grey appearance.

The ACL RACE Series performance engine bearing as manufactured have an appearance that is dark tarnished colouration, which can vary from dark black/brown/blue colours. This colour comes from the electroplated overlay that has copper as one part of its composition, which tarnishes to the dark colours described above. This tarnish colouration has negligible thickness and has no influence on bearing operation.

ACL RACE Series performance engine bearings do not start out with the silver grey appearance of regular after market bearings, as there is no final silvery tin flash applied to these bearings. Not applying a silvery tin flash to these high performance bearings is a specific design feature. A silvery tin flash for appearance and long term corrosion protection, as applied to the regular after market bearings, can under high loading and heat, move, with the plate migrating and causing high spots on the back of the shells and distorting the bearing. For this reason the ACL RACE Series performance engine bearings do not have a cosmetic silvery tin flash applied, so there is no risk of any overlay plate movement on the backs of the shells, giving better bearing to housing contact and better bearing performance and function.