The Borg Warner 310mm LU (A618, 47RH/RE, 48RE) piston damper cores are becoming scarce. After several rebuilds, the material supporting the friction material becomes weak, and deflection could result in failure. The Sonnax fully machined piston allows for a stronger and more durable replacement. The hardened bore reduces galling of the seal bore. Sonnax piston plate BW-DA-3P adapts to the OE damper assembly using BW-RV-2 rivets.