We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Unity 31-013400-4 front rear conversion kit in box

Unity

Unity 31-013400-4 Front and Rear Conversion Kit

SKU CH-N36X-0PZ0E

Converts air suspension to passive coil springs on front and rear axles for 1999–2006 Mercedes-Benz S-Class models excluding 4Matic

  • Converts air suspension to reliable passive coil springs on select Mercedes S-Class models
  • Fits 1999–2006 S320, S350, S420, S430, S500 and S600 except 4Matic
  • Backed by Unity’s 50 years of aftermarket suspension manufacturing experience
  • Designed for trouble-free installation and long-lasting reliability
  • Complete front-and-rear conversion kit with part number 31-013400-4

Conversion Kit for Mercedes S-Class

The Unity 31-013400-4 Front and Rear Conversion Kit replaces factory air suspension with passive steel springs. It fits 1999-2006 Mercedes-Benz S320, S350, S420, S430, S500 and S600 models. The kit is designed for owners who want to eliminate air-ride complexity and restore a conventional spring setup. It is not for vehicles equipped with 4Matic all-wheel drive.

Build Quality and Installation

Unity draws on over 50 years of aftermarket manufacturing experience to produce suspension components made for trouble-free installation. The Elite Suspension Line parts are built to deliver long-lasting reliability once fitted. The kit includes the necessary components to convert both front and rear axles in a single package. Professional installation is recommended to ensure correct geometry and safety.

Limits of the Air-to-Spring Conversion

Converting to passive springs removes the self-levelling and ride-height adjustability of the original air system. The vehicle will sit at a fixed height and will not compensate automatically for load changes. Electronic suspension warnings may appear on the dashboard unless the control module is coded or bypassed. The kit does not address 4Matic models, which have different suspension mounting points.

Highlights

  • Converts air suspension to reliable passive coil springs on select Mercedes S-Class models
  • Fits 1999–2006 S320, S350, S420, S430, S500 and S600 except 4Matic
  • Backed by Unity’s 50 years of aftermarket suspension manufacturing experience
  • Designed for trouble-free installation and long-lasting reliability
  • Complete front-and-rear conversion kit with part number 31-013400-4

Specifications

BrandUNITY

Questions about this item

How does the kit convert the factory air suspension on these Mercedes models?

The Elite Suspension Line Powered by Unity replaces the air-ride system with steel springs for a passive setup, delivering a trouble-free installation and long-lasting reliability across the listed S-Class chassis.

What physical space or mounting points does the kit require on a 1999-2006 S-Class?

It bolts directly to the original suspension mounting points on non-4Matic S320, S420, S430, S500 and S600 models, using the factory control-arm and subframe locations without modification.

Which installation step do DIYers most often overlook when swapping to this passive suspension kit?

Failing to disable and depressurise the air-suspension system before removal triggers fault codes and can damage the compressor; always follow the manufacturer's air-system deactivation procedure first.

Also in this aisle

People compared these

Same shelf, same checkout — eight coins and a 30-minute rate lock.