BC Racing ER Coilovers BMW 3 Saloon/Coupe RWD (Rear Integrated) E90/E92 (05-11) 5.5/6kg.mm

Key Features

• Linear valving
• 30 clicks of compression adjustment via the external reservoirs
• 30 clicks of rebound adjustment from the top of the damper
• Ride height adjustment separate to spring preload
• Camber adjustable top mounts (depending on model)
• Monotube damper design
• Pillowball top mounts
• Bearing mounted upper spring platform
• 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 the damper seal
• 1 year manufacturer warranty

Which kit is right for you?

External Reservoir

The external reservoir ER Series coilovers enable BC Racing to increase the oil capacity of the damper unit. The additional oil capacity reduces peak oil temperatures, thus decreasing variations in damping rates caused by changes in oil viscosity. This reduction in damping rate variations enhances handling and overall on-road and track performance.

Separate Compression and Rebound Damping Adjustment

By separating the adjustment for damping compression and rebound, the ER Series enables you to tailor the vehicle precisely to your requirements. When braking hard while approaching a corner, you aim for the car to shift weight onto the front tyres to optimise grip for braking and facilitate trail braking into the corner without encountering understeer.

Upon easing off the brakes during corner entry, you want to prevent the suspension from rebounding too quickly, as this would swiftly unload the front tyres, potentially inducing understeer. If understeer occurs, you must reduce steering lock promptly to lessen the workload on the tyres and enable them to regain traction, thereby reducing the vehicle's ultimate speed.

The compression damping adjustment allows you to refine how the car leans onto its front tyres during braking, while the separate rebound adjustment lets you fine-tune how the car reacts as you release the brakes to enter the corner properly, ensuring the front end remains stable. This capability enables you to apply power earlier and optimise corner exit speed, crucial as it determines the maximum speed attainable down the subsequent straight.

Corner Weighting Adjustment

The lower spring platform of the BC Racing coilovers is adjustable. This feature enables the car to undergo corner weighting for achieving optimal balance, ensuring maximum tyre efficiency.

Equal weight distribution is essential for each tyre on an axle. Hence, both front and rear tyres should bear equal loads. This ensures that both tyres contribute equally during cornering, enhancing overall grip, maximising cornering speeds, and reducing lap times.

Optional assistive springs are available for purchase to fine-tune wheel droop according to specific requirements.

Ride Height Adjustable

Ride height is set by the position of the coilover bottom mount. This mount can be adjusted up and down the damper body to provide a complete range of adjustments.

Since ride height is determined by an adjustable bottom mount rather than the spring platform, you maintain full damper travel regardless of the chosen ride height setting.

Damping Adjustment

BR coilovers boast a 30-way damping adjustment that combines both rebound and compression into a single adjuster, ensuring simplicity and ease of use. This adjustable feature enables you to fine-tune the vehicle to suit prevailing conditions.

By adjusting the damping on both the front and rear, you can alter the car's handling characteristics. For instance, increasing the damping force at the rear compared to the front will shift the vehicle towards a more oversteer-oriented setup.

In the context of drag racing with a rear-wheel-drive car, achieving optimal weight transfer to the rear tyres is crucial for maximum traction and to prevent wheel spin. To accomplish this, you would soften the rear dampers to allow quicker compression. Conversely, if the rear dampers were set too stiff, traction would be compromised.

On the other hand, in drifting, if you're struggling to break traction and experiencing understeer, stiffening the rear dampers while softening the front ones will reduce rear traction while enhancing front traction. This adjustment will loosen the rear of the car while minimizing understeer, thereby shifting the vehicle's handling characteristics more towards drifting than drag racing or regular road and track use.

Pillowball (Rose Joint) Upper Mount

Several BC Racing BR coilovers are equipped with pillowball upper mounts. These mounts are crafted from aluminium alloy, anodised, and then bead blasted to achieve a durable and high-quality finish.

The pillowballs, manufactured in Japan, are solid in nature, eliminating any flex or play typically found in standard rubber mounts. This enhancement results in improved response and handling.

Camber Adjustment

If your vehicle allows for camber adjustment, BC Racing coilovers automatically incorporate camber-adjustable aluminium pillowball top mounts. These mounts utilise the same high-quality Japanese-manufactured pillowball, offering the additional advantage of an adjustable top mount that enables you to set camber according to your requirements, whether it's for road, track, or drift purposes.

Corrosion Protection

The damper units are coated in black chrome steel to ensure excellent durability, even in the harshest European winters. Aluminium components, such as top mounts and locking collars, undergo an anodising process, while steel lower mounts undergo an electrophoretic deposition process followed by powder coating.

To maintain the highest standards of anti-corrosive properties, a random selection of steel components like brackets, dampers, and screws undergo a salt spray test once a month. This test helps to assess the quality of the protective processes and ensures that corrosion resistance remains at the highest possible standard.

High Quality Coil Springs

BC Racing coilovers exclusively utilise top-grade steel for their spring manufacturing. These springs are crafted from SAE9254 high-strength, durable, cold-wound steel.

Each spring undergoes compression testing, enduring over 500,000 cycles with less than 5% deformation.

Patented Concave Lower Locking Collar

Coilovers employ a locking collar to secure the bottom mount and prevent it from loosening. When the bottom mount loosens, the damper body may slide down into the bottom mount, causing a reduction in ride height on that corner, which can result in hazardous handling characteristics. This issue is widespread among coilovers in general.

BC Racing employs an innovative and patented design for the lower locking collar, featuring a bevelled edge that fits into a corresponding bevel in the coilover bottom mount. This significantly increases the surface area on which the locking collar operates, effectively preventing the common and dangerous problem of the locking collars coming loose.

High Quality Oil

BC Racing dampers employ an advanced shim stack design and premium-quality oil to consistently regulate the compression and rebound speed of the damper rod, even under the most extreme conditions.

As the vehicle traverses rough terrain, the compression and rebound motion of the damper rod heats the oil. Low-quality dampers often utilise inexpensive oil, which undergoes changes in characteristics with fluctuating temperatures. It is crucial to use high-quality oil capable of maintaining consistent viscosity across a broad temperature range. Once the oil begins to degrade, its properties change, resulting in alterations in damping and consequently, changes in the vehicle's handling characteristics.

BC Racing ensures the use of only high-quality oil, ensuring that damping rates are sustained not just for the immediate use (e.g., during spirited drives on back roads or on the track) but also for long-term durability. This prevents quick degradation of the oil over time, significantly extending the operating life of the dampers.

Nitrogen Pressurised Dampers

When you push a damper hard on the track or on high-speed bumpy roads, you can induce aeration in the oil and cause cavitation. This leads to foaming, effectively reducing the oil's viscosity and consequently diminishing the damping effect of the unit. While high-quality oil helps mitigate this issue, BC Racing takes an additional step by pressurising the dampers with nitrogen.

The nitrogen applies pressure on a floating piston, which in turn exerts a constant pressure on the oil, significantly reducing aeration and thereby enhancing the consistency and quality of damping. The pressurised nitrogen also introduces an additional element of effective spring rate to the damper unit.

Bearing Mounted Upper Spring Platform

Minimising stiction between the spring and its seats is crucial because the spring twists as it compresses. Failure to relieve this tension can lead to spring binding, causing the spring rate to alter slightly as the spring compresses and extends. The generated tension can rapidly deteriorate the spring perches and, in extreme cases, loosen the spring platform and locking collars. This can result in the platform and locking collars sliding down the damper, leading to uneven ride height and the risk of the spring dislocating during full damper extension.

The friction between the spring and seats also affects steering effort, as the springs turn with the wheels. This introduces unnecessary additional friction into the steering system, negatively impacting the vehicle's handling characteristics.

BC Racing's innovative design of the bearing-mounted upper spring platform addresses these issues. By significantly reducing stiction between the spring and its seats, BC Racing units avoid the aforementioned problems, improving the efficiency of the steering system and enabling the spring and damper to function as intended.

Optional Upgrades

Damper adjusting extenders - To save you the hassle of removing the parcel shelf every time you need to adjust the damping on your BC Racing coilovers, we offer pairs of adjuster extenders. These extensions attach to the adjuster knob on the top of the coilover and are available in three lengths: 110mm, 200mm, and 250mm. They can be attached in seconds with a simple grub screw design.

Assister spring perch - You might prefer to run some droop with your coilovers, or perhaps you want to modify the ride by adding an additional smaller assister spring. The spring perch and assister springs allow you to do this, with a wide range of spring rates available.

Pillowball top mount - Some applications come with standard hardened rubber top mounts to ensure a high-quality ride and keep costs reasonable for road use. However, we often provide a pillowball upgrade for these vehicles if you wish to eliminate this flex and enhance the car's performance. Upgrading to pillowball eliminates the inherent flex, even in the hardened rubber used by BC Racing, thus improving handling for those seeking the ultimate performance.