All too often, 4x4s are driven with too heavy a load. You might be towing a big boat or trailer, perhaps you have loaded up a large pile of sand for a construction project. Most often, when overlanding with the family, your vehicle is heavily loaded with the added weight of a canopy, drawer system, roof-top tent, awning, fridge and full tanks of water and fuel.
In these instances, the rear is sagging, headlights are pointing towards the sky, the steering is very light, and the suspension is hitting the bump stops on every undulation. Bad news.
You can fix things by adding an extra blade in the case of semi-elliptic leaf springs, or a heavy-duty set of rear coil springs. The downside will be a permanently harder ride – which is not always ideal when not carrying a load.
THE BASIC KIT
Airmax helper springs are a quick bolt-on installation in most cases. The Firestone air springs are installed between the chassis and the suspension of the vehicle. Air pressure is used to provide load support. In the kit:
Top and bottom brackets
Two Firestone air springs
5 metres ¼-inch DOT approved flexible tubing
Separate brass tyre valve for manual inflation
There is a solution from the Air Spring Supply Company in South Africa that offers the best of both worlds: Airmax air springs. This simple system comprises a pair of Firestone air springs (which are designed in the USA and sold under the Ride-Rite brand). These are held in place between the chassis and the spring pack by brackets. The pressure inside the air springs can be adjusted easily for changing loads, via a standard tyre valve which is routed to a convenient place on the vehicle via ¼-inch DOT approved tubing. More complicated air spring systems use an on-board compressor, an air holding tank, and separate valving for each airbag. This allows one to adjust ride height on the move, and even to level the vehicle left-to-right to compensate for uneven loads. Systems are also available for off-road trailers, including the big guns like the Conqueror Commander and Companion, offering adjustability for load and the benefit of levelling when stationary.
The Firestone air spring system has been extensively proven in heavy-duty truck and bus applications. The springs are also used in various industrial applications for pneumatic damping. They are not only very simple in concept and operation, they are also virtually maintenance-free. In vehicle applications, however, the fitment process should ensure there is no rubbing or abrasion between the air spring and suspension components through the full extent of wheel travel. A certain low level of pressure should also be kept in the bags (typically 0.5 to 0.7 Bar, with occasional pumping up to 3-5 bar to ensure the system is working optimally).
Air SPRING BENEFITS
-Levels vehicle when loaded
-Improves handling and braking under load
-Reduces suspension fatigue by preventing permanent sagging
-Reduces inter-leaf friction
-Prevents bottoming out which stresses the vehicle’s suspension
-Absorbs road shock and offers a better ride when loaded
Air springs will level out the vehicle when heavily loaded, and carry a range of additional benefits including a better ride and no bottoming out, but care must be taken not to exceed the vehicle’s recommended Gross Vehicle Weight Rating (GVWR). This is also known as the GVM (Gross Vehicle Mass) and is the legally allowable mass of the vehicle, plus passengers and loads (including weight on the towball).
With 35 years of experience, the Air Spring Supply Company is highly qualified to advise on any air spring application. ASSC supplies Airmax air spring systems to the commercial bus, truck and trailer industry, as well as the 4×4 and leisure industry.
ASSC has depots in Johannesburg and Durban, and can supply air spring systems countrywide.
To contact the JHB branch, fill out the form below.