…And what you need to do to fix it
Fact: We all want that extra little bit of ground clearance for our 4WDs. While the modern day 4X4 is very capable with stacks of mechanical and electronic traction aids, the first problem you’ll often run into is ground clearance. That can easily be sorted, though. Right?
When you’re lifting a live-axle 4WD, you will still leave your big beam axles right in the same spot, leaving only a negligible gain in overall clearance. On the other hand, modifying independent suspension setups can net you some nice clearance gains. But, there are other complications to worry about.
Changing the ride height of your 4X4 through suspension mods will inevitably throw your geometry out of whack. The two most important angles an IFS 4WDer should consider is caster angle and camber angle, which are both affected by suspension mods. Let’s get into some details.
Suspension travel and binding
Double wishbone suspension is designed with a short upper control arm (UCA), which can improve a vehicle’s handling by changing camber when cornering. But it also means that UCA quickly runs into trouble when things are modified.
One big issue with upper control arms and suspension lifts is the ball joint angle. As the vehicle gets lifted, the suspension components no longer sit at the middle of their travel range. The ball joint, a spherical bearing not unlike your shoulder or hip joint, is now always closer to binding up. A binding ball joint means it has limited down travel and will also flog out and fail much faster – things you definitely don’t want in a 4X4.
Caster angle is best understood when looking at your 4X4 from the side. A vehicle with neutral caster will have a steering axis that is directly vertical. A positive caster angle will have the steering angled with the wheel forward, while a negative caster is the other way around. Most vehicles normally have a small amount of positive caster, which helps the steering self-centre and stay steady.
When you add lifted suspension to your 4X4, the factory caster setting is affected. This will affect the way your 4X4 steers and handles in a big way. Things like steering feel and heaviness change, as well as bump steer and lightness.
Lifting your 4X4 also affects camber angle. Look at your 4WD from the front; camber is the angle that the wheels lean inward or outward. Race cars, for example, chase negative camber (top of wheel leaning inward) to improve the car’s cornering capability.
That sort of thing shouldn’t be that high on your 4X4 priority list though, right? Regardless, lifting an IFS 4WD will result in positive camber, which is undesirable: most 4WDs have a neutral (or close to neutral) camber, and giving a positive camber will reduce road holding. Also, you’ll have uneven tyre wear.
The fix? Aftermarket
What an aftermarket upper control arm can do is improve your caster and camber angles, which then improve drivability on-road. The ball joint angle can also be improved, giving your suspension more durability and available travel.
A common misconception about aftermarket upper control arms is that they return the suspension geometry back to standard, which isn’t true. Because you’ve modified your 4X4 with a new suspension setup, the factory geometry settings aren’t necessarily the best. Chances are, you’ve modified your wheels and tyres well, right?
A good upper control arm will have a little bit more of a positive caster to help accommodate for an increase in unsprung weight and ride height, and a neutral or slightly negative camber angle. This will help the car stay settled and self-centred on the highway, and help accommodate the different size and weight of your wheels and tyres.
This all means despite making some pretty big changes to your 4WD, you can maintain really good on-road drivability, durability and off-road capability by going beyond that basic spring/shock suspension upgrade.
Thinking about UCAs for your 4X4? Lucky for you, there are a handful of options out there. Suspension is something you definitely shouldn’t skimp on, and UCAs are part of that. Don’t shop on price alone, and do your research to see what options suit you (and your 4X4) best. Think about the materials used, ball joints and bushes, and what range of lift they accommodate. If you have different wheels and tyres, it’s also worth thinking about any issues with clearance or fouling.