On Air AL-KO Ducato / Boxer / Relay Rear Semi-Air Suspension Kit
Not sure which kit fits your chassis? [Contact Us], we've a fully staffed phone line with technical experts available.
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 (requires kit with compressor)
- 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. Read more about [Up Plating on our information page here].
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 Stub axle 80mm narrow to 140mm wide. Supplied for manual inflation via tyre inflator or workshop compressor.
AKS9201Z / AKS9202Z — Tag axle (two rear axles). Supplied with medium duty compressor as standard, with digital (9201Z) or analogue (9202Z) gauge panel.
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.
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
Optional compressor and control kits for AKS3101Z (standard kit):
- 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.
Fitting & Installation
Professional fitting is available at our workshop in Ongar, Essex — [Contact Us] to arrange. All parts are available for nationwide next day delivery. Full fitting instructions are included with every kit.
FAQ
Which kit do I need for my AL-KO motorhome? — Single or twin thru-chassis rear axle → AKS3101Z. Tag axle (two rear axles) → AKS9201Z (digital) or AKS9202Z (analogue). If unsure of your axle configuration, call before ordering.
Does this kit replace my AL-KO suspension? — No. Air springs fit alongside the existing torsion beam suspension; nothing is removed and the installation is fully reversible.
Will this kit increase my payload / legal weight limit? — No. The kit does not change your plated weight. Up-plating is carried out by a specialist third-party company; a rear semi-air kit is commonly a requirement of that process — confirm with your up-plating provider.
Do I need a compressor? — AKS3101Z is supplied for manual inflation via tyre inflator or workshop air. Optional compressor and gauge kits (PCP1029Z/1049Z/1069Z) add in-cab control; tag axle kits include a medium duty compressor and panel as standard.
Might I need anything else? — An additional cradle (AKS3111Z) may be required depending on chassis configuration — this can only be confirmed with the vehicle on a ramp. Applies to tag axle variants too.
Can you fit it for me? — Yes, at the Ongar, Essex workshop — call to arrange.