External Reservoir Race Tuned Coil overs
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External reservoir ER Series
BC Racings premium flagship coil overs are the external reservoir ER Series with separate compression and rebound damping adjustment. The ER Series coil overs 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.
The external reservoir ER Series coil overs 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.
Corner weight adjustment:
The lower spring platform of the BC Racing coil overs are adjustable. This allows the car to be set up for corner weighting to achieve perfect balance and ensures that maximum tyre efficiency is achieved. The car needs to be placing equal weight on each tyre on an axle so both front tyres need to be taking equal loading as do both rears. This makes sure that both tyres are doing their equal share of work when cornering which increases overall grip, maximises corner speed and reduces lap times. Optional assister springs can be purchased to allow wheel droop to be dialled into the unit to suit specific needs.
Ride height adjustment
Ride height is determined by the position of the coil over bottom mount. The mount can be wound up and down the damper body to give a full range of adjustment from near standard ride height to so low it wouldn’t be drivable on the road. Because ride height is determined by an adjustable bottom mount rather than spring platform you retain full damper travel regardless of the ride height run.
BR coil overs feature 30 way damping adjustment that combines both rebound and compression in one adjuster for simplicity and ease of use. This adjustable facility allows you to fine tune the vehicle to meet the relevant conditions. By tweaking front and rear damping you can adjust the way the car handles. Increasing damping force on the rear relative to the front, for example, will start moving the vehicle into a more oversteer orientated stance. If you want to go drag racing in a rear wheel drive car then you want the back of the car to squat off the line to maximise weight transfer to the rear and therefore onto the rear tyres. This maximises traction and helps prevent wheel spin. To achieve this you would soften the rear dampers to allow faster compression. If you had the rear dampers set to hard, as you might run the car on a race track, then the car would be less inclined to squat so traction would be reduced. Conversely, if you want to go drifting and are finding it hard to break traction and are having problems with understeer then making the rear dampers harder will help reduce traction whilst making the front dampers softer will give greater front traction. This will make the rear of the car looser whilst minimising understeer thus altering the vehicles handling characteristics more towards drift than drag, road or track.
Pillow ball (rose joint) upper mount:
Many of the BC Racing BR coil overs come with pillow ball upper mounts. The mount itself is made from aluminium alloy, anodised and then bead blasted to give a high quality, durable finish. The pillow balls themselves are of Japanese manufacture and their solid nature eliminates any flex or play associated with the standard rubber mounts so improving response and handling.
If its possible to include camber adjustment on your vehicle then the BC Racing coil overs automatically include camber adjustable aluminium pillowball top mounts. These feature the same high quality Japanese manufactured pillowball but give the added benefit of an adjustable top mount that allows camber to be set to suit your needs be it road, track or drift.
The damper units are black chromed steel to give superb durability even through the darkest of European winters. The aluminium components (top mounts, locking collars etc) are anodised and the steel lower mounts go through an electrophoretic disposition process followed by powder coating. A random selection of steel components (brackets, dampers, screws etc) are put through a salt spray test once a month to check the quality of the protective processes and that anti corrosive properties are kept at the highest possible standard.
High quality coil springs:
BC Racing coil overs only use the highest quality steel for their spring manufacturer. They are produced from SAE9254 high strength durable cold wound steel. The springs are compression tested through over 500,000 cycles with less that 5% deformation.
Patented concave lower locking collar:
Coil overs use a locking collar to prevent the bottom mount becoming loose. If the bottom mount becomes loose then the damper body can work its way down into the bottom mount so reducing ride height on that one corner which can lead to dangerous handling characteristics. This is a very common problem for coil overs in general. BC Racing utilise an innovative and patented designed lower locking collar with a bevelled edge that seats into a corresponding bevel in the coilover bottom mount. This vastly increases the surface area that the locking collar works on and so prevents the common and dangerous problem of the locking collars working loose.
High quality oil:
BC Racing dampers use a sophisticated shim stack design and high quality oil to consistently control the compression and rebound speed of the damper rod even under the most extreme conditions. As the vehicles travels over rough ground the compression and rebound motion of the damper rod heats the oil. Poor quality dampers use cheap oil whose characteristics alter with varying temperatures. Its vital that high quality oil is used that can maintain consistent viscosity under a wide temperature operating range. Once the oil start to degrade, its properties change leading to damping changes leading to changes in the vehicles handling characteristics. BC Racing ensures that only high quality oil is used so that damping rates are maintained not only for the moment in hand (i.e. whilst out for a back road blast on or track) but that long term longevity is maximised with oil that doesn’t degrade quickly over time thus extending the dampers operating life significantly.
Nitrogen pressurised dampers:
When you work a damper hard on track or on high speed bumpy roads you can cause the oil to aerate and cavitation can occour. This causes foaming which effectively reduces the oils viscosity and so reduces the units damping effect. High quality oil goes a long way to help reduce this problem but BC Racing go one step further and pressurise the dampers with nitrogen. The nitrogen exerts a pressure on a floating piston which in turn exerts a permanent pressure on the oil dramatically reducing aeration and so improving the consistency and quality of the damping. The pressurised nitrogen also adds an additional element of effective spring rate to the damper unit.
Bearing mounted upper spring platform:
Because the spring twists as it compresses it is very important to minimise stiction between the spring and its seats. If this tension is not relieved then spring binding can occur leading to the spring rate effectively altering slightly as the spring compresses and extends. The tension generated can lead to rapid deterioration of the spring pearches and in extreme cases can cause the spring platform and locking collars to loosen. This can lead to the platform and locking collars ‘walking’ down the damper resulting in un even ride height and danger of the spring dislocating under full damper extension. The friction between spring and seats also has an effect on steering effort as the springs are physically turned with the wheels. This introduces additional unnecessary friction into the steering system which has a knock on detrimental effect on the vehicles handling characteristics. The bearing mounted upper spring platform is one of BC Racings innovative designs. By vastly reducing stiction between the spring and its seats the BC Racing units avoid the above problems thus improving the efficiency of the steering system and allowing the spring and damper to work as designed.