Equipment Tests > 4WD Suspension Systems

But before you rush out and start modifying your 4WD with all the gear the off-road equipment salesman will gladly sell you there are a few thing to consider. Primarily, why do you want to modify the suspension? Is it for additional clearance; improved towing and load carrying; appearance only or is your old suspension clapped out and in need of replacement? Also, once modified, will your vehicle still be able to perform its day to day duties? That is; will a raised vehicle still fit under your carport, garage roof and local shopping centre carpark? Not only is the roof height an issue but raising a vehicle's suspensions alters the geometry of the suspension and steering components as well as the drive shafts. This can result in wheel alignment problems, driveline vibrations, excessive tyre wear and affect the operation of the system components. Speak to the specialists or other owners who have carried out similar modifications to check what ramifications you might expect.

If you're fitting heavy duty springs to cope with the weight of heavy loads the first thing you need to determine is just how heavy is your vehicle likely to be. This means loading it up with all the gear, accessories and people you're likely to be carrying on a trip and hauling it down to the local weighbridge to get an accurate fully-laden weight. Armed with the weighbridge ticket and the ride height you want the vehicle at, you can then go to your spring manufacturer or suspension supplier and he should be able to supply you the correct springs for the task ahead.

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Another point when fitting heavy duty springs for carrying large loads: these can make the vehicle skittish over holes and corrugations when the vehicle is unladen. If you only load your vehicle up once a year for a big trip and the rest of the time it hauls a relatively light load around town, then you may want to consider having two sets of springs and shocks on hand to get the best performance under the respective conditions. It is not that expensive an option and with a coil-sprung, live-axle vehicle such as an 80 Series LandCruiser it's not a difficult job to swap over the combinations.

A competent suspension supplier should also be able to recommend and supply the correct shock absorbers to match the new springs. This is most important as the extended and closed lengths of the shocks need to match the extension lengths of the springs and the valving needs to match the spring rate. Your best bet is to work with a suspension specialist when selecting aftermarket components.

Aside from the springs and dampers there's a host of bushes and balljoints that hold your suspension and steering together. These generally require regular checking and lubrication which should be done as part of your normal vehicle servicing routine. Once again, when these parts come up for replacement, either genuine manufacturers parts or aftermarket units can be used. In the case of bushes, many people opt for hard-wearing polyurethane items from aftermarket suppliers rather than the OEM rubber bushes.

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