BC RACING COILOVERS HM SERIES - BMW 3 SERIES E46 CONVERTIBLE (98-06)

The BC Racing HM Series builds on the capabilities of the RM range but adds fully independent 2-way damping adjustment for serious track use. Each HM kit features inverted monotube dampers with separate compression and rebound control, giving drivers the ability to fine-tune handling balance with far greater precision.

The inverted damper design relocates critical damper fluid and internal components away from heat sources such as brakes and hubs. This helps prevent damper fade during extended track sessions and improves long-term consistency. By moving the majority of the damper mass upward toward the chassis, unsprung weight is reduced, resulting in sharper steering response, improved wheel control, and a more composed ride.

Combined with external reservoirs and a digressive piston design, the HM Series is engineered for demanding track environments where stability, heat management, and precise damping control are essential.

Key Features

• Digressive piston and damping curve
• 30 levels of independent rebound and compression adjustment
• Inverted damper design (vehicle dependent)
• Dual piston system (one piston in the reservoir, one in the damper)
• Teflon-coated steel braided reservoir lines (inverted applications)
• Solid reservoir stems for double A-arm vehicles
• Tapered bottom mount locking collar
• Pillowball top mounts
• Dust boots to protect damper seals
• Custom spring rates available
• Spare parts available with short lead times
• 1-year manufacturer warranty

Spring Rate Options

The HM Series is designed for intensive track use, where heat control, chassis stability, and damping precision are critical. The Recommended spring rate offers a balanced baseline suited to most track layouts and tyre setups.

Higher rates are available for cars running slicks, aero, stiffened chassis, or for drivers who prefer a more aggressive response. Softer spring rates may be chosen for dual-purpose cars that still see regular road miles, but the HM Series naturally caters to performance-focused builds.

If you're unsure which spring rate suits your car, tyre choice, or track usage, get in touch and we’ll help you choose the right setup.

Options Available

Not all configurations apply to every vehicle.

• HA Series – Aluminium front top mounts with rubber centres; rear aluminium rubber mounts or no rear mounts.
• HH Series – Front camber-adjustable pillowball mounts; rear pillowball mounts or no rear mounts.