Setting up your 4WD Suspension

We help many customers’ select aftermarket 4WD suspensions. Some do it because they want a lift, some because they want a better ride and others because they want to carry more weight in their vehicle. Others want a combination or all three.

Many customers are under the mistaken impression that putting heavier duty springs in their vehicle will make the ride stiffer. In theory this should be true, but in fact the quality of the suspensions manufacturers put in their vehicles these days is that poor that by putting in a quality aftermarket suspension you can in fact improve both the ride and the load carrying capacity of your 4WD. This is only true to a point however, if you put really heavy duty springs in you will make the ride much harsher unless you are carrying a heavier load to make the springs work correctly.

It’s quite easy to select heavy duty springs for vehicles that carry a load all the time. The hard part comes where vehicles are unloaded some of the time and loaded the other part. In this instance the vehicle owner has two choices. The first is to select a spring somewhere in the middle. Something which isn’t too stiff when unloaded and does the job when loaded.

The other option is to fit an air bag suspension so that you can vary the pressure in the air bags to cope with different loads. In this way you can select a spring that gives a good ride with a light load and then increase the pressure in the air bags when a load is required to be carried. This is a great set up as long as you are willing to vary the pressure in the bags. You’re probably not going to do it for a short trip, but if you intend to load up the vehicle for a long trip or work requirements this is a good option.  You can set your air bags up with a compressor and gauges in the vehicle so that you can flick a switch to vary the air bag pressure. This is a great setup but expensive.

Some customers ask us what is better: putting in new springs or air bags? The main point being that they want to save money and installing both options can be expensive. The answer is that one does not replace the other. Good air bags will help you carry more load, but if your springs are sagged the air bags won’t generally improve the ride to the level it should be. Many times you can just get away with putting in some good quality springs and you can increase the load carrying capacity by 100 to 200kgs and still get a good ride. The trouble starts when your load varies significantly from unloaded to loaded; this is where air bags should really be used.

The other situation we get a lot of, is customers wanting to improve the load carrying capacity of their Ute. Many customers want to add toolboxes, extra fuel tanks, etc to their Ute and find the springs sag as a result. If a customer puts an extra 300kgs of equipment on their Ute, it’s quite easy to select a spring that will carry that load on an ongoing basis. Again the case for air bags starts where the vehicle owner wants to vary the load every now and then.

In all cases we recommend that you get the services of an experienced 4WD sales person or mechanic that specialises in suspensions. Once you have selected a new suspension you’re pretty much stuck with it, so it pays to get some expert advice to get the vehicle set up correctly.

We also recommend that you get a wheel alignment done after installing a new suspension and get the brake bias of your vehicle checked as lifting the vehicle or changing the spring rate will generally affect how your rear brake bias controller works. Over reliance on air bags to carry you load will also affect how the brake bias controller works too, so it’s important that air bags only be used to assist in carrying the load, not to do the main part of the job.

The last aspect of suspensions I want to cover in this article is your shock absorbers. I’m not going to go into the different types of shockers here, but it’s important when you upgrade your springs that you also upgrade your shockers. Genuine shockers are not designed to handle heavier duty springs and will not perform well. They generally tend to fail fairly quickly after aftermarket springs are fitted.

To sum up, genuine suspensions are generally very poor quality these days and we see many new 4WD vehicles with their suspensions already sagged in the show rooms or within the first 10,000kms. I think vehicle manufacturers are pinching pennies these days and the quality of their suspensions is no exception. If you want a better ride, want to be able to carry a load, of want a bit more ground clearance, a good aftermarket suspension might be the way to go.