Description
BMW E85 Z4 M (06-08) BC Racing RM coilover kit 5/8 kg/mm
The BC Racing RM coilover kit Z4 M (part number I-22-RM-MA) is a coilover kit adjustable in height and damping, also simply called a coilover, for the BMW Z4 M (E85), model years 2006 to 2008. The spring rate is 5 kg/mm front and 8 kg/mm rear.
The RM series is aimed at a Z4 M that covers most of its kilometres on track days, at hill climbs or in tarmac rallies. On MacPherson struts BC Racing uses an inverted monotube, on other suspension types an upright monotube.
The digressive piston and the fully synthetic oil with a very high viscosity index ensure that the damping changes little when the dampers are warm after a few sessions. With 30-click damping adjustment you tune the Z4 M to the course.
Key benefits
- Inverted monotube: on the MacPherson struts of the Z4 M.
- Synthetic oil with a very high viscosity index: consistent damping as the temperature rises.
- Digressive piston: firm control over slow body movements.
- 30 clicks: compression and rebound adjustable together.
- Spring rate 5/8 kg/mm: the same spring rate as the BR and DS for the Z4 M.
- Pillowball top mounts or camber plates at the front: with rubber or the original mounting at the rear.
- For track days, hill climbs and tarmac rally: that is what the RM was developed for.
- Rebuildable: the dampers can be rebuilt.
Suitable for
BMW Z4 M Roadster (E85) with rear-wheel drive, model years 2006 to 2008
- Track days and long track sessions
- Hill climbs and tarmac rally
- A Z4 M used mainly for motorsport
Technical specifications
- Manufacturer: BC Racing
- Part number: I-22-RM-MA
- Series: RM, inverted, for track days, hill climbs and tarmac rally
- Spring rate front/rear: 5/8 kg/mm
- Damper design: inverted monotube on MacPherson struts, upright monotube on other suspension types, digressive piston, fully synthetic oil with a very high viscosity index
- Damping: 30 clicks, compression and rebound simultaneously
- Ride height: steplessly adjustable via the damper body
- Top mounts: pillowball top mounts or camber plates at the front, rubber or original mounting at the rear
- 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; noise from track use is not covered by the warranty
Fitting and delivery
The kit is vehicle-specific and replaces the original dampers and springs of the Z4 M. We recommend having it fitted by an experienced mechanic. On some cars the pillowball top mount at the front requires a small modification to the upper mounting; if in doubt, contact us. BC Racing advises periodic greasing for the RM and ZR series and recommends them less for road use than the BR, DS, ER or ZX. Have the wheel alignment reset after adjusting height and camber. The delivery time is 1 to 2 weeks as long as the manufacturer has stock. If the kit is temporarily not in stock at BC Racing, you can still order; we will tell you the delivery date.
The BC Racing RM for the BMW Z4 M combines inverted dampers on the MacPherson struts with fully synthetic oil and 30-click damping adjustment.
Why choose this RM coilover kit Z4 M?
The RM is made for a Z4 M that is mainly driven on track, on the hill or on the rally stage: digressive damping, synthetic oil that is less sensitive to temperature and 30 steps to tune the car. If you also drive the Z4 M a lot on the road, look at the BR or DS.
BC Racing coilover kits for the BMW Z4 M E85
Overview of the BC Racing series for the BMW Z4 M E85 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-22-BR-RA | 5/8 | 30 clicks, linear, pillowball top mounts front | Road with the occasional track day |
| DS | I-22-DS-DA | 5/8 | 30 clicks, digressive, pillowball top mounts front | Track-focused, sporty road use |
| RM (this kit) | I-22-RM-MA | 5/8 | 30 clicks, digressive, synthetic oil, pillowball top mounts front | Track days, hill climbs, tarmac rally |
For the regular BMW Z4 E85 (not the Z4 M), BC Racing has separate kits. Their part numbers start with I-12.
Frequently asked questions
What is the difference between the BC Racing RM and DS for the Z4 M?
The RM coilover kit Z4 M is aimed at track days, hill climbs and tarmac rally and has inverted dampers on the MacPherson struts and fully synthetic oil; the DS is a track-focused monotube that is also suitable for sporty road use. For the Z4 M, both have 5/8 kg/mm, a digressive piston and 30 clicks.
Is the BC Racing RM for the Z4 M suitable for road use?
Not primarily. BC Racing advises periodic greasing for the RM series and recommends it less for road use than the BR, DS, ER or ZX.
Does the BC Racing RM for the Z4 M also fit a Z4 M Coupe (E86)?
That has not been confirmed. BC Racing UK lists this kit for the rear-wheel-drive Z4 M E85, model years 2006 to 2008, and does not mention the Coupe E86. If you have a Coupe, please contact us before ordering.
What is the delivery time of the BC Racing RM coilover kit for the Z4 M?
1 to 2 weeks, as long as the manufacturer has stock. If it 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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