BC RACING BMW 3 SERIES E36 92-98 (EXCL M3)BR Series Coilover The BR series coilovers use a large 46mm diameter piston in a 53mm diameter damper body to maximise oil capacity. As the damper unit operates the oil contained within heats up. The viscosity of oil changes as its temperature varies which can lead to changes in the damping characteristics of the unit. BC Racing only use a very high quality oil with their coilovers but go that extra mile to maximise performance and build their BR