A Quick Guide to 4WD Suspension
Standard 4WD vehicle suspension is installed by the manufacturer to suit as wide a range of uses as possible and to feel good right out of the showroom; in other words, it's a compromise. This goldilocks suspension is neither too hard nor too soft, too high nor too low. And, perhaps most importantly, is cost-effective.
The functions of suspension are many and need to be coordinated to suit specific uses, but the two main properties effected are ride and handling. Ride refers to the suspension’s ability to smooth out bumps, while handling is characterised by safe cornering, acceleration and braking. In addition to these, off-roaders will also likely consider wheel travel – the up and down range of a wheel – and road-holding abilities, ride height, body roll and load capabilities.
(Image: Bushings, struts, torsion bars and airbags have a part to play in balancing out various suspension systems.)
Springs absorb energy from bumps and allow wheels to travel up and down. The most common forms are coil springs, which are the prototypical curly kind, and leaf springs, which employ layers of curved steel. Vehicles may be fitted with only one kind or a combination of the two – it’s not unusual for 4WDs to have coils at the front and leaf spring at the back. This kind of arrangement makes use of the coil’s wheel travel properties for rugged terrain and the load-carrying properties of the rear leaf.
Shock absorbers or dampers soften the jarring effect that occurs when a wheel hits a bump, prevent bounce and help push the wheels down to gain traction. In a 4WD vehicle, they’re likely to be longer and softer than a road vehicle. Many shock absorbers can be tuned to produce different ride qualities by adjusting the resistance of fluid flow within.
Other components such as bushings, struts, torsion bars and airbags have a part to play in balancing out various suspension systems. Though these smaller parts may not get as much attention as springs and shock absorbers, a good system will consider them just as carefully.
Aftermarket suspension upgrades offer a plethora of specialised configurations, allowing vehicle owners to gear their vehicle towards specific uses. But it's important to remember that there's always a bit of give and take. For example, what feels great off-road may feel sluggish on the blacktop; it's important to consider all variables.
(Image: Off-road vehicles require greater articulation (up and down movement), which is often accompanied by an increased ride height.)
Load-carrying ability can be achieved with a Gross Vehicle Mass (GVM) upgrade, which will also allow a vehicle to tow loads with a higher ball weight. If you are towing, however, it's important to note that these upgrades will not increase your Gross Combination Mass (GCM).
Off-road vehicles require greater articulation (up and down movement), which is often accompanied by an increased ride height. Longer springs and shocks and an increased spring rate allow for greater wheel travel and will also facilitate the fitting of bigger tyres. Keep in mind, there are legal limits on how much lift can be added to your vehicle.
Comfort and handling are relative to how a vehicle is used, but a suspension upgrade doesn't have to mean your vehicle will be any worse off when driving on the blacktop – or any surface, for that matter. Manufacturer fitted components are designed to feel good on a test drive out of the showroom, they're supposed to feel more car-like. So if you plan on doing anything you wouldn't do in a Honda Civic, then you'll most likely be more comfortable with a few adjustments. The key is to have the system designed and installed by professionals.