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Two black rubber air spring bags with metal end caps

Unity

Unity Rear Air Spring Kit 525401-525402

SKU CH-1DVY-DFT5V

Rear air spring kit with two bags fits 1999–2003 BMW 525i, 528i and 540i models

  • Restores smooth air ride with two replacement air spring bags
  • Fits BMW 525i 2001-2003 and 528i 1999-2000 models
  • Compatible with BMW 540i 1999-2003 for direct replacement
  • Backed by Unity's 50 years of aftermarket suspension expertise
  • Engineered for trouble-free installation and long-lasting reliability

Unity Rear Air Spring Kit

The Unity rear air spring kit replaces worn rear air springs on compatible BMW models. It contains two air spring bags designed for direct installation. The kit fits 2001 to 2003 BMW 525i, 1999 to 2000 BMW 528i, and 1999 to 2003 BMW 540i vehicles. It is intended for owners restoring factory air suspension performance.

Sustained Load Behaviour

The air springs support the rear axle continuously under varying passenger and cargo loads. They maintain ride height and damping consistency during extended highway driving or daily commuting. The design resists fatigue from repeated compression and extension cycles over time. This helps preserve the original air ride quality throughout the service interval.

Build Quality and Mounting

Unity manufactures these springs using materials selected for durability in aftermarket suspension applications. The components align with original equipment mounting points for a trouble-free fit. The kit includes both left and right units so the axle remains balanced. This simplifies the restoration of the complete rear air suspension system.

Highlights

  • Restores smooth air ride with two replacement air spring bags
  • Fits BMW 525i 2001-2003 and 528i 1999-2000 models
  • Compatible with BMW 540i 1999-2003 for direct replacement
  • Backed by Unity's 50 years of aftermarket suspension expertise
  • Engineered for trouble-free installation and long-lasting reliability

Specifications

BrandUNITY

Questions about this item

Does the rear air spring kit generate noticeable noise or heat during extended highway driving?

The Unity rear air spring kit contains no moving or electrical parts, so it produces no operational noise or heat during all-day driving.

What existing suspension components must the vehicle already have for this kit to install correctly?

The kit fits 1999-2003 BMW 528i, 525i and 540i models that already use factory air suspension with compatible upper and lower mounting points.

Will the 525401-525402 air springs work alongside the original shock absorbers on a 2001 BMW 525i?

Yes, the Unity air springs are designed to pair with the original shock absorbers on 2001-2003 BMW 525i models without modification.

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