Description
BMW E46 3 Series Convertible (98-06) BC Racing HM coilover kit 5.5/8 kg/mm
The BC Racing HM coilover kit E46 Convertible (part number I-90-HM) is a coilover kit adjustable in height and damping, also simply called a coilover, for the BMW 3 Series E46 Convertible, model years 1998 to 2006. The spring rate is 5.5 kg/mm front and 8 kg/mm rear.
The kit brings two BC Racing series together. HM combines the inverted dampers of the RM with the 2-way reservoir technology of the ER, for serious track work.
On the MacPherson struts, an inverted monotube with a double piston does the work, which keeps the strut stiff under high lateral loads. The external reservoir is connected with PTFE-coated, braided steel lines and contains the second piston. You set compression and rebound in 30 clicks each, independently of each other. The tuning is digressive, the oil synthetic and the spring rate is 5.5/8 kg/mm.
BC Racing only releases the I-90 for the E46 Convertible. For the E46 Sedan, Coupe, Touring and Compact there are the kits with part number I-02.
Key benefits
- Inverted monotube on MacPherson: stiff against bending forces in fast corners.
- 2-way adjustable: compression and rebound 30 clicks each, independently of each other.
- External reservoir with second piston: more oil volume and an extra piston outside the damper.
- PTFE-coated braided steel lines: durable connection between damper and reservoir.
- Digressive tuning: plenty of control during slow body movements.
- Synthetic oil: stable at high temperatures.
- Camber plates: on suitable kits, rubber top mounts optional.
- Spring rate 5.5/8 kg/mm: for the E46 Convertible.
Suitable for
BMW 3 Series E46 Convertible, model years 1998 to 2006 (BC Racing part number I-90)
- Serious track use and club racing
- Drivers who want to combine the stiffness of an inverted kit with 2-way adjustment
- Cars with lots of grip and high cornering speeds
Technical specifications
- Manufacturer: BC Racing
- Part number: I-90-HM
- Series: HM, inverted 2-way with external reservoir
- Spring rate front/rear: 5.5/8 kg/mm
- Damper design: inverted monotube on MacPherson with double piston and external reservoir, digressive
- Damping: 2-way, compression and rebound 30 clicks each, independent
- Ride height: steplessly adjustable via the damper body
- Top mounts: camber plates on suitable kits, rubber top mounts optional
- Contents: dampers and springs front and rear, lower mounts, top mounts where applicable, adjustment spanners and warranty card with serial number
- Warranty: 1 year on manufacturing defects. With this track-focused series, noise is not covered by the warranty
Fitting and delivery
When fitting, allow time to mount the reservoirs securely and to route the lines so that they do not rub anywhere at full bump, full droop and full steering lock. Have a wheel alignment done on the E46 after setting the height. BC Racing advises periodic greasing of the HM series and recommends it less for road use than the BR, DS, ER or ZX. The delivery time is 1 to 2 weeks as long as the manufacturer has stock. If the kit is not in stock, you can still order and we will keep you informed of the delivery date.
The HM is what you get when you do not want to have to choose between the stiffness of an inverted damper and the freedom of 2-way adjustment.
Why choose this HM coilover kit E46 Convertible?
Anyone who drives an E46 hard and often on track runs into two limits: the stiffness of the front strut and the limited adjustment of a 1-way damper. The HM tackles both at once. The result is a car that stays stable under high loads and that you can fine-tune per session.
BC Racing coilover kits for the BMW E46 Convertible
Overview of the BC Racing series for the BMW E46 Convertible supplied by Race4DriftParts, with the BC Racing part number. Spring rates in kg/mm, front/rear.
| Series | Part number | Springs f/r | Damping | Intended for |
|---|---|---|---|---|
| BR | I-90-BR-RA | 6/8 | 30 clicks, linear | Road with the occasional track day |
| DS | I-90-DS-DA | 6/8 | 30 clicks, digressive | Track-focused, sporty road use |
| RM | I-90-RM-MA | 5.5/8 | 30 clicks, digressive, synthetic oil | Track days, hill climbs, tarmac rally |
| ER | I-90-ER | 5.5/8 | 2-way, 30 clicks per direction, external reservoir | Serious track and competition use |
| HM (this kit) | I-90-HM | 5.5/8 | 2-way, 30 clicks per direction, external reservoir | Serious track use |
| ZX | I-90-ZX | 5.5/8 | 3-way (20/12/30 clicks), external reservoir | Competition, long sessions, drift |
| ZR | I-90-ZR | 5.5/8 | 3-way (20/12/30 clicks), external reservoir | Competitive motorsport |
Frequently asked questions
What is the difference between the BC Racing HM and ER for the E46 Convertible?
The HM coilover kit E46 Convertible uses an inverted monotube on the MacPherson struts, which is stiffer under high lateral loads. Both are 2-way with an external reservoir.
Does this kit also fit an E46 Sedan, Coupe or Touring?
No. BC Racing only releases this kit for the E46 Convertible. For the Sedan, Coupe, Touring and Compact there is the I-02.
Why does the BC Racing HM coilover kit have a second piston in the reservoir?
With the second piston in the external reservoir, part of the damping work is done outside the damper itself, with more oil volume available. That is how the HM series is built.
What is the delivery time of this BC Racing HM coilover kit?
The delivery time is 1 to 2 weeks as long as the manufacturer has stock. If the kit is temporarily sold out, you can still order and we will let you know when it arrives.
Delivery outside the European Union: different shipping costs may apply. Don’t worry: we will email you as soon as possible after your order and agree the shipping with you. You are not committed to anything without your consent.
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