Bilstein® 40-221601 - B3 Series™ Rear Driver Side OE Replacement Air Spring

The delicate axial bellows of the air spring provide very sensitive spring behaviour with a comparably low rolling radius. This ensures optimum functionality even in confined working chambers. Due to the permanent load (contraction, extension, different pressures and temperatures), the material is worn out and may eventually leak. If the air bellows cannot be inflated any more, the vehicle is no longer fit to drive. Technical further developments from the original application to today’s part are usually easily recognizable. Due to higher efficiency and Bilstein’s obligation to increasingly employ environmentally friendly materials, the sheathing of the bump stop no longer contains chromium VI. Apart from that, all old parts by Bilstein are recycled in an environmentally friendly manner via the Partslife initiative. Due to the permanent movement and mileage, the high gas-pressure and the permanent oil contact, the seals in particular will become worn. If oil leaks, the air suspension module and other parts such as seals and valves lose their functionality.