BMW E70 X5 Rear Coil Spring Bilstein B3 36-301140 - Fast Road, Track Day, Daily Driver

Bilstein B3 rear coil spring 36-301140 for E70 X5 (2006-2013). Not a soft OE replacement. Not a show-car poseur part. A properly engineered fast road or track day spring - stiff enough to sharpen rear axle response, stable under load, and durable enough for daily driver abuse.

Searches this part actually matches: E70 rear coil spring, Bilstein 36-301140, X5 E70 fast road suspension, track day rear spring E70, stage 1 E70 upgrade, daily driver X5 coilover prep.

• Hot-set chrome vanadium steel - no sag, no height loss, even after UK winters and track heat cycles
• Surface-compressed & corrosion-protected - built for real use, not showroom shelves
• Fits all E70 X5 variants: 30i, 35i, 40i, 50i, 30d, 35d, 40d, xDrive - no exceptions, no fitment notes needed
• Designed as a matched set - always replace both rear springs for balanced handling and geometry

Because race car.