BC Racing ER Series Coilover Kit – Mazda MX-5 Mk1/Mk2 NA/NB 1989–2005 • N-04-ER

BC Racing N-04-ER ER Series Coilover Kit

BC Racing ER Series coilover kit for Mazda MX-5 Mk1 NA and Mk2 / Mk2.5 NB / NB-FL 1989–2005 applications listed in the compatibility table.

The ER Series is BC Racing's two-way adjustable external-reservoir suspension system, designed for drivers who want significantly greater control over damper setup for demanding fast-road, track-day and motorsport use.

Separate compression and rebound adjustment allows each aspect of the damper response to be tuned independently. Compression adjustment is provided through the external reservoirs, while rebound adjustment is controlled separately at the damper, with 30 adjustment positions available for each.

The external reservoirs increase the available damper oil capacity, helping reduce peak oil temperatures and maintain more consistent damping characteristics during sustained hard use. Ride height can also be adjusted independently from spring preload, giving greater flexibility when configuring the suspension.

• Product type: Complete coilover suspension kit
• Series: ER Series
• Primary use: Fast road, track day and motorsport
• Location / system: Front and rear suspension
• Brand: BC Racing
• Product reference / part number: N-04-ER
• Vehicle application: Mazda MX-5 / Miata NA & NB 1989–2005
• Damper design: Monotube with external reservoirs
• Front spring rate: 8 kg/mm
• Rear spring rate: 6 kg/mm
• Damping adjustment: Two-way independent compression and rebound adjustment
• Compression adjustment: 30 clicks via the external reservoirs
• Rebound adjustment: 30 clicks from the damper adjuster
• Ride height adjustment: Adjustable independently from spring preload
• Top mount note: Pillowball top mounts front and rear
• Quantity supplied: Complete four-corner coilover suspension kit

Fitment advice: Designed for Mazda MX-5 / Miata NA and NB platform applications from 1989–2005, including applicable 1.6, 1.8, 1.8 VVT and turbocharged models listed in the compatibility table. For imported, modified or previously repaired cars, matching the vehicle generation, chassis code, suspension layout and kit reference is recommended before ordering.

Other items to consider: When fitting or setting up this product, you may also want to consider purchasing replacement suspension fasteners, anti-roll bar links, suspension bushes and any worn suspension arms or ball joints. A professional four-wheel alignment and suspension setup should be carried out once the final ride height has been established.

Useful tools / consumables: Suitable vehicle lifting equipment and axle stands, socket and spanner set, torque wrench, penetrating fluid, anti-seize compound and the appropriate coilover adjustment tools. Professional wheel-alignment equipment is required for final geometry setup.

Difficulty guide: DIY Difficulty: Advanced. Installation involves complete front and rear suspension replacement together with positioning of the external reservoirs, ride-height adjustment and subsequent geometry setup. Professional installation is recommended for this type of suspension system.

Why BC Racing? BC Racing ER Series suspension combines external reservoirs with independently adjustable compression and rebound damping, providing considerably greater setup control than a conventional single-adjustable coilover. Increased damper oil capacity, monotube construction, independent ride-height adjustment and extensive damping adjustment make the ER Series particularly suitable for demanding fast-road, track-day and motorsport applications.

What’s in the box: Complete four-corner BC Racing ER Series coilover suspension kit with front and rear external-reservoir dampers, springs, pillowball upper mounts, adjustment hardware and associated components supplied with the N-04-ER kit.

Installation / setup notes: The external reservoirs must be positioned and secured correctly during installation. Ride height, spring preload, compression damping and rebound damping should be set methodically. Once the required ride height has been established, all mounting hardware should be tightened to the appropriate specification and a full four-wheel geometry alignment carried out before final suspension tuning. BC Racing notes that supplied spring rates may differ where a kit has been ordered with a custom specification.