4WD IFS Upgrades

Some manufacturers (eg Toyota, Mitsubishi and Nissan) have moved to a double wish bone coil over strut design. This is a vast improvement on the torsion bar setup. This configuration allows manufacturers to design progressive rate coil springs which improves ride, comfort and handling. They also provide more options for modification to add offroad capability. This design uses a coil spring over the front strut and A shaped upper and lower control arms attached to the chassis in two positions. The outer ends of the control arms attach to the steering knuckle. This usually includes a long spindle or king pin that connect the two control arms. This design provides a significant number of modification points as not only can the coil spring and strut be replaced, advanced IFS suspension kits also provide replacement upper and lower control arms and steering knuckle and spindle modification.

Whilst the modern IFS vehicle has the advantage of allowing greater under diff clearance than a conventional live front axle, wheel travel is greatly limited by the CV’s. The longer wheel base of the IFS utes makes this less relevant off road. In ramp travel tests, a live axle vehicle looses contact with the ground at the rear wheel whereas an IFS ute looses contact with the ground at the front wheel. The rear wheels still have plenty of traction to push the IFS vehicle further on 3 wheels. In the bush, this will often allow the IFS ute clear the obstacle.

There are basically four techniques to add lift to a coil sprung IFS ute. Add a simple strut spacer; fit a standard suspension kit comprising of matching struts, shocks and springs; fit a more advanced coil over kit which may include additional components such as upper control arms and diff spacers; or buying an advanced kit that provides more lift though much more sophisticated bracketometry and possibly replacement cross members. As with any modification, your ultimate decision will be based on your budget and what you want to do with your vehicle.

One option out there in the market place is a simple spring spacer that is bolted on above the strut and coil spring. Whilst this is a cheap modification, and you may get away with that if your ute never ventures off the bitumen, my advice to you is to avoid it like the plague! When you fit a spacer, you move the shock absorber down. At rest, the control arms are now a lot further away from the bump stops. Under compression, the strut can bottom out before the bump stops engage. This can (and has) lead to catastrophic strut failure as the strut is asked to carry the whole weight of the car instead of just absorb the bumps like it was designed to do. Spacers also let the suspension droop more than then the manufacturer allowed for. This can lead to ball joints running out of travel, binding, getting damaged or even worse, letting go all together!  Either way, the prospect of something letting go when in the middle of the Simmo is a good reason to fit a quality suspension lift that is properly set up for your vehicle.

 Don’t confuse these spacers that sit on top of the strut with thinner plastic spacers inserted in with the spring. These are about 5mm thick and are available from ARB. The purpose of these is to trim an overall suspension setup. The 5mm thick spacer provides about 10 mm of lift due to suspension geometry. You need to dismantle the spring to fit these.