Nissan Silvia S13 / Cefiro A31 (89-94) BR Series
Group D Customer Information:
Here at Group D, we have been using and distributing BC Racing suspension with great success for many years now. In our experience, the combination of great damping characteristics, wide damping adjustment range, independent height adjustment, durability through quality construction, a comfortable ride, the ready availability of service parts to keep your coilovers feeling fresh for many years into the future, plus BC's one year warranty, makes BC Racing the easy choice when choosing suspension for your pride and joy.
We use BC Racing suspension on our daily rides, as well as many of our Group D competition cars and our customers' cars, and we have amassed a wealth of experience throughout the years which we can pass on to our customers in order to help you to choose the correct coilover set, in the correct spring rates, for your application.
Unless otherwise stated as a front or rear pair, each product is a full set of BC Racing coilovers. We are working to update our image gallery to display images of the actual kit for each and every set, however some sets may still have a generic image of two coilovers displayed. Don't worry, it will be a full set which you will receive!
Spring rates
There is a common misconception that coilovers will make your car uncomfortable, however this is thankfully not the case. We can have your BC Racing suspension made in pretty much any spring rates to achieve pretty much any ride quality you want, from limo-like smoothness, all the way to a hard ride for owners who want to run their cars low and with a stanced wheel fitment, and do not want their arches rubbing. We of course also cater for drift and race car customers and can provide expert knowledge in order to fine tune your suspension's performance.
A spring rate is the amount of force required to deflect a spring over a certain distance, and basically, the higher the number, the stiffer your spring will be. The first number refers to the front spring rate, and the second number refers to the rear spring rate, so for instance 6/5kg.mm means that the front coilovers have 6kg/mm springs fitted, and the rears have 5kg/mm springs fitted. BC Racing will have the correct damper fitted to each set in order to ensure that the spring and damper performance are in harmony.
A spring rate's effect on ride stiffness depends on a number of factors, mainly the chassis type and the car's weight. We will be happy to assist you in choosing the correct spring rates for the result which you want to achieve. Engine swaps and other special circumstances are not a problem.
BC Racing have a recommended spring rate for each suspension set, and this will always be the first option available from the list on our website. BC's recommended rate is designed to be a nice middle ground between comfort and handling, and will be the ideal set for 95% of customers. It is also the most cost effective.
Please feel free to contact us if you have any queries about which BR Racing set to purchase, or which spring rates to choose for your car and application.
BR Series - For fast road
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 characteristic 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 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.
Key Features
* Pillowball top mounts
* Bearing mounted upper spring platform
* Camber adjustable top mounts (depending on model)
* Ride height adjustment separate to spring preload
* 30 way adjustable damping
* Monotube damper design
* Tapered bottom mount locking collar to prevent collar working loose
* Custom spring rates available
* All spare parts available with low lead times
* Dust boot to protect damper seals
* 1 year manufacturer warranty
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 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 coilover bottom mount. The mount can be wound up and down the damper body to give a full range of adjustment.
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.
Damping adjustment
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 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.
Pillowball (rose joint) upper mount
Many of the BC Racing BR coilovers come with pillowball upper mounts. The mount itself is made from aluminium alloy, anodised and then bead blasted to give a high quality, durable finish.
The pillowballs 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.
Camber adjustment
If its possible to include camber adjustment on your vehicle then the BC Racing coilovers 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.
Corrosion protection
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 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 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.
Optional upgrades
Damper adjusting extenders – to save you the time and trouble of removing the parcel shelf each time you want to adjust the damping on your BC Racing coilovers we can offer pairs of adjuster extenders. These attach to the adjuster knob on the top of the coilover and are available in three lengths, 110mm, 200mm and 250mm. They attach in seconds with a simple grub screw design.
Assister spring perch – you might prefer to run some droop with your coilovers or maybe you want to alter the ride by adding an additional smaller assister spring. The spring perch and assister springs allows you to do this. The springs are available in a wide range of spring rates.
Pillowball top mount – some applications come with hardened rubber top mounts as standard to ensure the highest quality ride and keep costs as reasonable as possible for road use but we often offer a pillowball upgrade for these vehicles should you want to remove this flex and make the car a little more hardcore. Upgrading to pillowball eliminates the flex inherent in even the hardened rubber used by BR Racing so improving the handling for those looking for the ultimate.
This is the kit we recommend for the best balance of performance and comfort, designed by the factory to have the best overall compromise of spring rate, ride height range, top mount design and damping rate to suit the majority of car owners.
It is more than capable of dealing with fast road and track work but also retains a high degree ride civility so the car can still be used for mundane duties and long journeys without the ride becoming tiring.
