Our External reservoir ER Series comes with separate compression and rebound damping adjustment. The ER Series coilovers bring with them the high quality and unique features seen on the BR and RM type but have the additional benefit of external reservoirs and the ability to allow the end user to individually adjust and set compression and rebound damping rates.
 
External reservoir
The external reservoir ER Series coilovers allow BC Racing to increase the oil capacity of the damper unit. The additional oil capacity reduces peak oil temperatures which decreases variations in damping rates due to oil viscosity changes. The reduction in damping rate variations improves handling and ultimate on road and track performance.
 
Separate compression and rebound damping adjustment
By separating the adjustment for damping compression and rebound the ER Series allows you to dial the vehicle in to your exact needs. When braking hard whilst approaching a corner you want the car to transfer weight to the front tyres to maximise grip for the braking effort and also to allow you to trail brake into the corner without the car understeering.
As you start to lift off the brakes on corner entry you don't want the suspension to snap back up too quickly as this will remove the loading from the front tyres too quickly and lead to understeer. As soon as the car starts to understeer you need to wind off the steering lock to reduce the work effort applied to the tyres to allow them to regain traction. This slows the vehicles ultimate speed.
The compression damping adjustment allows you to fine tune the way the car rolls onto its front tyres during braking and the separate rebound adjustment allows you to fine tune the way the car responds as you come off the brakes to enter the corner proper and keep the front end hooked up. This allows you to get back on the power sooner and maximise corner exit speed. Corner exit speed is vital because this determines you maximum speed achieved down the next straight.