On Air AL-KO Ducato / Boxer / Relay Rear Semi-Air Suspension Kit

Is your motorhome's rear sitting too low?
 
If your Fiat Ducato, Peugeot Boxer or Citroën Relay motorhome scrapes on ferry ramps, steep driveways or inclines when loaded — or the rear simply sits lower than it should when you're carrying extra water, batteries or gear — this is the kit designed to help.
 
On Air's rear semi-air suspension kit for AL-KO AMC chassis motorhomes gives you on-demand control over your rear ride height. Raise the rear when you need clearance. Level up when parked. Adjust for load. All without altering the original AL-KO suspension — the air springs work alongside it, not instead of it.
 
Why AL-KO Chassis Motorhomes Have This Problem
The AL-KO chassis is one of the best motorhome platforms available — its low frame design provides a lower floor for larger internal living space than standard alternatives. But that same low frame can mean the rear sits closer to the ground from the outset. Add any meaningful load — water, batteries, solar equipment, passengers, gear — and the rear drops further. For many owners, the result is regular scraping on ramps, ferries and steep inclines.
 
This is not a fault. It is the nature of the chassis. The On Air semi-air kit is the aftermarket solution.
 
What the Kit Does
The air springs are fitted alongside the existing AL-KO torsion beam suspension — nothing is removed. You retain the low floor benefits of the AL-KO chassis while gaining adjustable rear ride height control.
 
Raise the rear on demand — clear ferry ramps, steep driveways and long overhang situations
Level under load — counteract rear drop caused by carrying extra weight
Independent left/right adjustment — compensate for off-centre loads
Increased roll stiffness — more stability in crosswinds and when passing high-sided vehicles
Improved suspension travel — refined ride height leading to increased comfort at all legal payloads
 
Also a Likely Requirement for Up-Plating
If you're planning to have your motorhome's legal kerb weight increased — to accommodate lithium batteries, extra water or additional equipment — fitting a rear semi-air suspension kit is commonly a requirement of the up-plating process. This kit does not itself increase your legal kerb weight. Up-plating is carried out by a separate specialist third-party company, and whether this kit is required should be confirmed with them.
 
Which Kit Do I Need?
 
Three variants of this kit are available depending on your chassis configuration and preferred controls.
 
AKS3101Z — Standard single or twin rear axle For AL-KO AMC chassis X250/X290 Ducato, Boxer and Relay motorhomes from 2007 onwards with a single or twin thru-chassis rear axle. Stub axle: 80mm narrow to 140mm wide. Supplied ready for manual inflation — air is added via a standard tyre inflator or workshop compressor.
 
AKS9201Z — Tag axle, digital gauge panel For X250/X290 Ducato, Boxer and Relay motorhomes from 2007 onwards fitted with the AL-KO AMC tag axle configuration — two rear axles. Supplied with medium duty compressor and digital gauge panel as standard.
 
AKS9202Z — Tag axle, analogue gauge panel For X250/X290 Ducato, Boxer and Relay motorhomes from 2007 onwards fitted with the AL-KO AMC tag axle configuration — two rear axles. Supplied with medium duty compressor and analogue gauge panel as standard.
 
Tag axle motorhomes are typically higher-specification builds carrying greater payload — a medium duty compressor is included as standard on both tag axle variants to reflect this.
 
If you are unsure which axle configuration your motorhome has, or want to confirm compatibility before ordering, please contact us before purchasing.
 
Compressor and Controls
AKS3101Z (standard kit): Supplied ready for manual inflation. For added convenience, optional compressor and control kits are available:
PCP1029Z — Ducato X290 compressor and dual gauge kit
PCP1049Z — Ducato X290 compressor and digital gauge kit
PCP1069Z — Ducato X290 dual panel medium duty compressor kit
 
AKS9201Z / AKS9202Z (tag axle kit): Compressor and gauge panel included as standard in your chosen display format.
 
For fully automatic load levelling, all variants are compatible with the On Air Active Advanced Air Suspension Control System (CKA9001Z), which continuously monitors and adjusts ride height using a single height sensor.
 
Technical Specification
 
AKS3101Z Platform: X250/X290 AL-KO AMC Year range: 2007 onwards Vehicles: Fiat Ducato, Peugeot Boxer, Citroën Relay Axle variant: Single or twin thru-chassis Stub axle: 80mm narrow to 140mm wide Compressor: Optional
 
AKS9201Z / AKS9202Z Platform: X250/X290 AL-KO AMC Year range: 2007 onwards Vehicles: Fiat Ducato, Peugeot Boxer, Citroën Relay Axle variant: Tag axle (two rear axles) Medium DutyCompressor: Included as standard
 
An additional cradle (AKS3111Z) may be required depending on exact chassis configuration — this can only be determined once an engineer is under the vehicle. Contact us if you have any concerns before ordering.
 
Fitting & Installation
Professional fitting is available at our workshop in Ongar, Essex — call 01277 552030 to arrange. All parts are available for nationwide next day delivery. Full fitting instructions are included with every kit.