Mazda MX5 89-05 NA/NB BC-Racing Coilover Kit BR-RS
BR Series Street and Circuit Coilover
Pillowball upper mount*
Camber adjustable top mounts*
Aluminium top plates*
30 way adjustable damping
Adjustable spring platform
Height adjustment via bottom mount to retain full damper travel
Bearing mounted upper front spring platform
Dust boot to protect damper seals
* Some features are dependent on model
The BR series coilovers use a large 46mm diameter piston in a 53mm diameter damper body to maximize 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 characteristic of the unit.
BC Racing only use a very high quality oil with their coilovers but go that extra mile to maximize performance and build their BR range with a large 53mm diameter damper body. This increases the capacity of the unit which increases the volume of oil contained which in turn reduces the peak temperature and so significantly improves damper performance.
Corner weight adjustment:
The lower spring platform of the BC Racing coilovers are adjustable. This allows the car to be set up for corner weighting to achieve perfect balance and ensures that maximum tire efficiency is achieved.
The car needs to be placing equal weight on each tire on an axle so both front tires need to be taking equal loading as do both rears. This makes sure that both tires are doing their equal share of work when cornering which increases overall grip, maximizes corner speed and reduces lap times.
Optional assister springs can be purchased to allow wheel droop to be dialed into the unit to suit specific needs.
Ride height adjustment
Ride height is determined by the position of the coilover 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 very low. The actual maximum lowering differs per application. 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 coilovers 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 over steer 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 maximize weight transfer to the rear and therefore onto the rear tires. This maximizes 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 under steer 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 minimizing under steer thus altering the vehicles handling characteristics more towards drift than drag, road or track.
If it’s possible to include camber adjustment on your vehicle then the BC Racing coilovers automatically include camber adjustable aluminium pillow ball top mounts. These feature the same high quality Japanese manufactured pillow ball 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 anodized 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 coilovers 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:
Coilovers 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 coilovers in general. BC Racing utilize an innovative and patented designed lower locking collar with a beveled 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. It’s 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 maximized with oil that doesn’t degrade quickly over time thus extending the dampers operating life significantly.
Nitrogen pressurized 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 occur. 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 pressurize 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 pressurized 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 (static friction) 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.
Difference in Series:
The BR-Series is BC-Racing’s latest coilover model with up to date technology. Depending on your car the coilover kit will have rubber or pillowball topmounts, or no topmounts at all. For example if you car has double wishbone suspension it is not needed to use pillow ball mounts and we advise to use the rubber ones. With double wishbone you also cannot adjust camber with the front top mounts, so in most cases it would make no sense to take the more expensive pillow ball top mounts. In some cases we DO offer the pillow ball mounts as an upgrade, why is that?: Pillow ball top mount – The applications that come with hardened rubber top mounts as standard are to ensure the highest quality ride and keep costs as reasonable as possible for road and track use but we often offer a pillow ball upgrade for these vehicles should you want to remove this minimal flex and make the car a little more hardcore. Upgrading to pillow ball eliminates the flex inherent in even the hardened rubber used by BC Racing so improving the handling for those looking for the ultimate.
The product title shows the exact specification of the set, and here is a list of all possible options you can find in the product title:
BR-RS Series: Front = Rubber Topmount, Rear = Rubber Topmount
BR-RA Series: Front = Pillowball Topmount, Rear = Rubber Topmount or No Topmount
BR-RH Series: Front = Pillowball Topmount, Rear = Pillowball Topmount
BR-RN Series: Front = No Topmount, Rear = Rubber Topmount or No Topmount
Remember: This is not always a specification you can choose but it all depends on the car’s original suspension technology. We have already chosen the best suitable option for the average driver based on the possibilities of the car.