AL-KO Chassis Air Suspension Kits
Many motorhomes are built on an AL-KO chassis because it can provide extra floor space and, in some cases, an increase in payload thanks to its lighter construction compared with the standard chassis. However, that lower floor height can also create problems.
Low-floor AL-KO motorhomes can be more prone to grounding out, especially on ferries, steep drives, petrol station entrances, rough campsites and uneven tracks. Heavily loaded vehicles can also compress the torsion bar rear suspension significantly. As this type of suspension has limited travel, the result can be a poor ride quality, reduced clearance, and a vehicle that feels harsh or unsettled on the road. Larger motorhomes with a long rear overhang often suffer the most, as the combination of low ride height and extended rear bodywork makes rear-end grounding a real issue.
This is where the right AL-KO air suspension kit can make a real difference. It helps lift the rear of the motorhome, improves ground clearance, and can make a major difference to both ride quality and handling. On some vehicles it can also form part of a chassis uprating package, allowing you to legally carry more weight where appropriate.
Why AL-KO Air Suspension Matters
Rear air suspension on an AL-KO chassis is not just about lifting the back of the vehicle. When properly designed and installed, it can help with a wide range of common motorhome problems and make the vehicle more usable in real-world conditions.
Typical benefits can include:
- Improved rear ride height and ground clearance.
- Reduced rear-end sag when heavily loaded.
- Better control and stability.
- Improved comfort on poor road surfaces.
- The ability to fine-tune the vehicle for different loads and conditions.
- Reduced bangs and crashes over bumps, potholes and rough road surfaces.
- Improved side-to-side adjustment where one side of the motorhome carries more weight than the other.
Because the left and right air bags remain independent, the system can also help compensate for uneven loading side to side, which is very common on motorhomes with kitchens, washrooms, garages, water tanks or heavy storage concentrated on one side.
Air suspension can make a major improvement, but it is not a substitute for correct loading, good tyres, sound dampers and a properly maintained base vehicle.
How to Recognise an AL-KO Chassis
When customers contact us about air suspension for their Fiat Ducato, Citroen Relay, Citroen Jumper or Peugeot Boxer motorhome, the first thing we ask is whether the vehicle has leaf springs or an AL-KO chassis.
If you are not sure, the simplest way is to look underneath the vehicle. We cannot identify this accurately from the registration number or VIN alone.
A standard chassis with rear leaf springs will have two curved steel springs running along the rear axle area. On heavily loaded vehicles these springs may look quite flat, which is very common.
An AL-KO chassis is different. If there are no rear leaf springs and the vehicle has a galvanised C-section chassis, it is usually the torsion bar type AL-KO chassis. We have included several photos in this post to show the AL-KO chassis from different angles.
It is also important not to confuse AL-KO air top with AL-KO chassis. They are not the same thing. AL-KO air top air bags are fitted to some leaf spring motorhomes and usually have a distinctive red or orange rim. We are regularly contacted by owners needing replacement bags after the bag has caught on the bracket. If you have an AL-KO air top system and need advice, please get in touch.
If you have a tag axle vehicle with two rear axles, also called twin rear axles, and therefore 4 separate wheels on the rear (total of six on the vehicle) then it is more likely that you have an AL-KO torsion bar suspension set up. We can still offer air suspension for these vehicles, but due to the limited distances between front and rear axles it is sometimes necessary to modify the mounting brackets, or to move the inner shock mount. Feel free to call for more info.
What Makes Our Kit Different
Our AL-KO kits are made by us in small batches here in Norwich using thick 6 mm British-sourced steel, then powder coated for durability.
The heavy-duty brackets are fitted in addition to the existing torsion bar suspension and are supplied with Firestone 9000 air bags. They may look simple, but they are extremely capable and well suited to this application.
One important point with AL-KO chassis is that there is not just one version. There are 23 known AL-KO chassis variants, so our kits are available in several widths to suit different applications. To make sure the kit fits properly, we ask customers to provide a few simple chassis measurements before ordering.
Our rear AL-KO kit is designed for Fiat Ducato X250, X290 and X295 based motorhomes, and also fits the equivalent Citroen Relay, Citroen Jumper and Peugeot Boxer models of the same generation.
It is not designed for Mercedes, Renault or VW AL-KO rear chassis applications, but if you send us measurements we will always try to help where possible.
When we first started making AL-KO kits around ten years ago it was a steep learning curve, and development took many iterations to perfect. As is often the case, competitors see what we are doing and offering and try to emulate it. That is flattering, but it can prove costly for customers. The loads on AL-KO suspension are higher than on leaf spring vehicles in some key areas. On alternative offerings we have seen failed welds, broken brackets and very commonly bent and distorted brackets. If a product is copied without fully understanding the application, then this is an inevitable consequence, and it often proves costly for the end user. We have had to repair, replace and upgrade many competitors' AL-KO chassis air suspension kits that were simply not up to the job. Some did not actually do anything noticeable.
Front Air Suspension Options
We can also supply front air suspension struts for Fiat Ducato, Citroen Relay, Citroen Jumper and Peugeot Boxer from 1994 onwards.
Although we cannot currently supply the rear AL-KO kit for all other base vehicles, we can also help with front suspension on some VW T5/T6, Mercedes and Renault based AL-KO motorhomes where the front suspension uses struts.
We do not have air suspension for motorhomes with a transverse leaf spring on the front, such as Iveco and Sprinter.
Schrader Valves or On-board Air?
We are sometimes asked whether the AL-KO kit can be run on simple Schrader valves. In this case, the answer is no.
Our AL-KO rear kit includes a compressor as standard because there is no single fixed pressure that delivers all the benefits in all situations. Motorhome loading, terrain, road conditions and access angles vary too much. To get the best from the system, you need to be able to adjust the pressure when required, and that is far more often than on a leaf spring vehicle.
For customers who want proper in-cab control with an air tank, we recommend our Standard OBA pack, which is our most popular option for motorhome owners and ideal for regular adjustment. This pack includes:
- A 25% duty cycle compressor.
- A small 2 US gallon steel tank.
- A twin button and gauge controller.
- An on-board air hook-up kit to match the compressor.
The left and right air bags remain independent, so they can be set to different pressures if needed.
We do not join the bags together, unlike some systems on the market. Linking both sides can allow air to transfer across the vehicle during cornering and movement, which is not something we consider safe and therefore also not legal.
If you want a more powerful setup with a lighter tank, our Premium OBA pack includes a 100% duty cycle compressor and an aluminium tank.
Uprating and Re-rating
On some vehicles, the kit may be used as part of an uprating package, but uprating is always vehicle-specific.
If you are buying the kit as part of a re-rating process, speak to your chosen re-rating company first.
Our kits are often used as part of that process, but we do not offer re-rating ourselves and we do not get directly involved in it.
Is This the Right Type of Kit for Your Motorhome?
This type of kit is especially worth considering if your motorhome:
- Bottoms out at the rear.
- Struggles with ferry ramps or steep entrances.
- Has a long rear overhang.
- Feels harsh or unsettled when loaded.
- Sits visibly low at the rear.
- Crashes and bangs over bumps, potholes and poor road surfaces.
- Leans more heavily to one side because of layout or loading.
Need Advice?
Not sure whether your motorhome has an AL-KO chassis or a standard leaf spring rear suspension? Send us a few clear photos from underneath the rear of the vehicle, along with a few basic measurements, and we will do our best to point you in the right direction. If your vehicle has a tag axle, or you want to discuss front and rear air suspension options, please call or email.