Retro-Fitting Air Suspension Units - Motorhome Forums, Motorhome Discussion, Motorhome Chat

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Retro-Fitting Air Suspension Units

Retro-Fitting Air Suspension Units.

My MH has a GVW of 3300kg. I considered that not enough so decided to upgrade using air suspension units. Originally I was going to have them fitted professionally, but the firm I was going to use went out of business. I then looked at the possibility of fitting them myself (and saving a couple of hundred pounds too).

Fitting them at home is not complicated and took me and my son just over three hours. I consider next time I could do it in about two hours as we were being ultra-cautious doing it for the first time.

What you will need a good trolley jack and some adequate axle stands, plus the necessary small spanners.

I chose the kit offered by VB-Air suspension which included pressure relief valves.
VB Airsuspension UK Ltd
Unit 13, Elder Court
Lions Drive
Shadsworth Business Park
Blackburn BB1 2EQ
T. 01254 848010 F. 01200 300110

Start by making sure that the vehicle is on stable level ground and jack up the rear end so that the axles stands can be inserted under chassis frames. In our case we couldn’t use the main longitudinal chassis members because there were too many attachments, so we used the main cross member.

Allowing the weight to be taken by the axle stands let the axle hang from the chassis. This allowed the original bump stops to hang free.

I had the previous night doused the bump stop fixings with penetrating oil. They spun off quite easily by hand. Having done this both sides, it remained to fit the new air bladders in their place. It was necessary to fit the air supply tubes to the bladders at this point as the union would be inaccessible once the unit was in place.

We found it easier to compress the bladders and hold them in that condition by the use of large cable ties. This made the overall size of the unit smaller and gave more room for manoeuvre. The unconnected bladders are quite easy to compress by hand.

In this picture it can be seen how the bladders are located. The upper “U” section site either side of the main chassis rail of the vehicle. The pin projecting up in the centre is inserted into the hole from which the original bump stops had been unscrewed. The flatter section on the bottom sits over the “U” bolts securing the leaf spring to the axle. There is an additional location pin which sits alongside the inner edge of the spring leaves.

The air supply tubes are then routed to a convenient point on the vehicle where the Schrader valves, pressure relief valves and the gauges can be fitted. We simply followed the brake lines.

On the X244 Sevel Van chassis (precursor to the X250) there is a hole on the cabin floor, above which is a rubber grommet. This grommet seals off the hole through which the handbrake cable passes on the other side. We chose to install the valves and gauges on the passenger seat valance, where it was both out of the way and visible at the same time.

The connection of the valves and gauges looks a little complicated but in fact is quite simple.

The final result is quite pleasing.

In use I have found that a good pressure to use is 2.25bar, which stiffens up the suspension to a point where comfort of ride is not sacrificed, but allows the load to be increased to the axle. The stability of the vehicle is very much improved and so far (1000 miles) I am very pleased.

Tony Collins (Tco)
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