Defender 90 Air Suspension Kits — Rear-Only and 4-Corner
We also offer a full fitting service from our Ongar, Essex workshop. Please call us on 01277 552030.
Looking for the Defender 110 or 130 kit? Click here for Defender 110/130.
Land Rover's Defender has been used worldwide in demanding conditions and remains in service alongside modern 4x4s and military vehicles. The 90 is the original short-wheelbase Defender — a shorter overall length and tighter turning circle than the 110 and 130, and a shorter distance between the axles, which changes how the vehicle sits and how it moves over uneven ground.
On Air Suspension builds Defender 90 kits in two formats. The rear-only kit fits air springs to the rear axle. The 4-corner kits replace the coil suspension at all four corners with a complete air system, available with electronic controls, and with Koni or Fox shock absorbers on two of the variants. All kits are designed and built by On Air Suspension.
Rear-Only or 4-Corner?
Rear-only (AKF1790Z) fits air springs to the rear axle and is inflated manually, via a tyre pump or workshop air supply. There is no compressor, ECU or cabin controls. Ride height is set by inflating the springs directly. It is the lowest-priced specification in the Defender 90 range and the usual starting point where the requirement is levelling the rear under load — towing, roof loads, rear-mounted carriers, or a Defender that sits down at the back when loaded. An onboard compressor and control system can be fitted afterwards.
4-Corner replaces the coil suspension front and rear. With the electronic control system fitted, height is adjustable to pre-set positions and is held under load up to full GVW.
The compressor and control system are a separate step and can be added to either format. Rear-only with a compressor fitted gives onboard air and automatic levelling at the rear without converting the front.
How the System Works
Standard Defender coil suspension is a fixed compromise between off-road ability, load carrying and road use — the spring rate is set at manufacture and does not change with load. An air spring's rate varies with the pressure inside it, so a 4-corner air conversion allows the vehicle height to be set to a chosen position and, on kits with controls, held at that position regardless of load up to full GVW.*
Wheel travel is maintained at every height setting rather than being reduced at the extremes. Air spring rates are matched front to rear at each ride height. In-house designed strut towers and shock mounts set the suspension geometry for the Defender 90, and each part has been through the On Air Suspension in-house R&D process for this platform specifically.
Bespoke air spring units are used with a 4-corner, 4-sensor automatic control system on the kits with controls. Electronic components have been durability tested and in many cases are shared with those fitted to European factory-fit air suspension cars. The AMK compressor** is a unit selected for low noise and vibration.
*Please refer to Land Rover for Defender official payload capability.
**AMK compressor included in the 4-corner kits with controls.
Kit Options
- AKF1790Z — Rear Only. Rear axle air springs, manual inflation. No compressor or controls.
- AKF1390Z — Manual 4-Corner. Air springs at all four corners, manual inflation. No electronic control system.
- AKF1290Z — 4-Corner + Controls. Adds ECU, height sensors, AMK compressor and cabin controls. Pre-set heights and automatic levelling. Supplied for use with the customer's choice of factory-spec shock absorbers.
- AKF1090Z — 4-Corner + Controls + Koni. As the controls kit, supplied with Koni shock absorbers matched to the air spring rates.
- AKF1090ZF — 4-Corner + Controls + Fox. As the controls kit, supplied with Fox shock absorbers matched to the air spring rates.
- AKF2290Z — LowRider 4-Corner + Controls. Non-ARB LowRider variant with full electronic controls and AMK compressor. Confirm fitment suitability before ordering.
Shock absorbers are supplied only with AKF1090Z (Koni) and AKF1090ZF (Fox). The other variants are supplied for use with the customer's choice of factory-spec shock absorbers, within the extended-length limits below.
Pre-Set Heights (Kits With Controls)
- Access height — lowered for entry and exit, approximately -50mm
- Ride height — normal road use
- Off-road height — increased clearance, approximately +40mm
- Multi-axis horizon levelling add-on available on request
The manual 4-corner and rear-only kits have no pre-set positions; height is set by inflating the air springs directly.
Technical Specification
4-corner kits
- Wheel travel — approximately 180mm
- Off-road position — +40mm (kits with controls)
- Access position — -50mm (kits with controls)
Rear-only kit (AKF1790Z)
- Rear axle air springs, manual inflation
- No pre-set height positions
Compatibility
Please follow this compatibility list — fitting parts outside these limits can damage components in the kit. The figures below apply to the 4-corner kits. For rear-only fitment requirements, call the workshop on 01277 552030.
Bump stops. A minimum bump stop height of 70mm from the chassis is required. 70mm bump stops are supplied to replace the standard Land Rover items. LowRider kits use the standard 58mm Land Rover bump stops.
Anti-roll bars. Passive front and rear anti-roll bars must be fitted. Not required on LowRider kits.
Shock absorbers. +2" shock absorbers with maximum extended length 606mm front, 610mm rear. LowRider kits: standard-length shocks only, maximum extended length 545mm front, 535mm rear.
Bushes. Rubber bushes recommended. Polybushes restrict suspension movement and create noise.
Lead time
These kits are built to order. Expect 7–10 business days. Contact us for an estimate; updates are provided through the build.
FAQ
Can you fit air suspension to a Land Rover Defender 90?
Yes. On Air Suspension builds Defender 90 kits in two formats: rear-only, and full 4-corner. The 4-corner kit replaces the standard coil suspension at all four corners with a complete air system, supplied with air tank, airlines, brackets, compressor, ECU, controls, air springs and a choice of Fox or Koni shock absorbers. Fitment requires minimal drilling. A full fitting service is available at the On Air Suspension workshop in Ongar, Essex.
Can I start with a rear-only Defender 90 kit and add a compressor later?
Yes. The rear-only kit (AKF1790Z) fits air springs to the rear axle only, inflated manually via a tyre pump or workshop air supply. It has no compressor, ECU or cabin controls, and it is the lowest-priced specification in the Defender 90 range — the usual starting point where the requirement is levelling the rear under load. An onboard compressor and control system can be added afterwards, giving automatic levelling at the rear. The rear-only kit is the rear half of the 4-corner kit, so a vehicle running rear-only can also be taken to full 4-corner later by adding the front components — strut towers, shock mounts and front air springs — with nothing already fitted removed or replaced.
How does air suspension change how a Land Rover Defender drives?
Standard Defender coil suspension is a fixed compromise between off-road ability, load carrying and road use. A full 4-corner air conversion lets the vehicle height be adjusted to pre-set positions, holds a constant ride height regardless of load up to full GVW, and maintains wheel travel at every height setting. In-house designed strut towers and shock mounts set the suspension geometry for the Defender 90.
What ride height settings does the Defender air suspension kit have?
Kits with the electronic control system offer pre-set heights: an access position lowered for entry and exit (approximately -50mm), a normal ride height for road use, and an off-road position with increased clearance (approximately +40mm). Wheel travel is around 180mm and is maintained at every height setting. A multi-axis horizon levelling add-on is available on request. On the manual and rear-only kits, height is set by inflating the air springs directly, with no pre-set positions.Which Defender 90 kits are supplied with Fox or Koni shock absorbers?
Fox and Koni shock absorbers are supplied as part of two specific variants: AKF1090Z with Koni, AKF1090ZF with Fox. Both are damper rates matched to the air spring rates and are otherwise the same specification as the 4-corner controls kit. The manual, controls and LowRider variants are supplied for use with the customer's choice of factory-spec shock absorbers. Contact the On Air Suspension workshop to discuss which setup suits your use.
What is included in the On Air Suspension Defender 90 air suspension kit?
The 4-corner kits are supplied with air tank, airlines, brackets, compressor, ECU, controls, bespoke air springs, and — on the Koni and Fox variants — matched shock absorbers. Kits with controls include an AMK compressor, a unit selected for low noise and vibration. The rear-only kit is supplied with rear air springs, brackets and airlines for manual inflation. The system is designed in-house using proprietary parts, with electronic components durability tested and in many cases shared with those fitted to European factory-fit air suspension cars.