How many times have you seen a 4WD with a nice-looking lift towing a camper trailer with its nose in the air and rear end almost scraping the bitumen? What about the opposite, where the front of the 4WD is lifted, the rear end is dragging, and the camper is at a bizarre angle? If this is you, we hope to help you with this guide to suspension for your 4WD and your camper with some great insights from Ironman 4x4 suspension specialist, Kristian Ristell.
IS YOUR SUSPENSION SUITABLE FOR OFFROAD TOWING?
The OE suspension on most 4WD vehicles is designed to suit all conditions but is heavily biased towards offering great performance and handling on-road, with a smidge for the offroad stuff. This is why aftermarket suspension is so advantageous, as you can upgrade your suspension to suit your needs. As Kristian points out, “Whether a person is setting up their vehicle for load carrying or greater comfort, or to drive on tougher terrain, aftermarket specialists can provide a suspension package to suit.”
You might set your tow vehicle up for touring by adding a bullbar, roof rack, storage drawers etc, and then upgrade your suspension to suit, but add a camper trailer to the mix and it all changes because extra weight is being added to the rear of your vehicle.
“Once you change the weight of a vehicle, the original suspension is no longer well configured to control that weight. If you do not upgrade and are carrying heavier loads, you can encounter problems with ride height control, that is, where the vehicle sits with a load applied. At a more severe level, the vehicle may be driving close to the bump stops and the impact may be more regular than normal, which can affect the safety of the vehicle,” Kristian said.
“Upgrading your suspension ensures the dynamics and velocity control for that vehicle are sound so the vehicle is not bobbing and bouncing down the road, nor body rolling any more than it needs to around corners.”
HOW DOES A SUSPENSION UPGRADE IMPROVE OFFROAD TOWING PERFORMANCE?
Upgrading your suspension not only improves the comfort level of the ride, but it also eases the strain on the vehicle and increases safety levels.
“By increasing the practical load carrying of the vehicle with stronger springs and more control in the shock, that vehicle will be better balanced; it won’t bounce or jump around as much as it did on the original suspension. It also improves handling as a heavy load on a soft spring creates a very low level of oscillation making the vehicle sluggish, unresponsive and doughy to drive. Selecting the right suspension upgrade can correct that,” Kristian said.
By adding more robust and longer springs and shocks your wheel travel, articulation and ride height are all increased, as is your ground clearance.
“When towing a camper trailer over rough terrains, like Simpson Desert dunes, you might find the vehicle rocks back and forth. To fix this, Ironman 4x4 ensure correct spring rates and damping to control and suppress that unwanted motion. Any weight on the tow ball is being applied so far back it creates a greater leverage effect on the rear suspension than if the load was directly over the axle. This can reduce the load on the front of the vehicle and create an imbalance. This can be rectified by recalibrating the dynamics of the vehicle and ensuring the correct ride height.”
HOW ELSE CAN YOU IMPROVE YOUR ALREADY UPGRADED SUSPENSION?
You’ve upgraded the suspension on your tow rig and tuned it to suit your setup and preferred ride, but your rear end still sags once the camper is hooked up? Thankfully there is a cost-effective solution — airbags.
The main players on the Australian market are Polyair and Airbag Man who offer solutions for both coil and spring suspensions. Having run the Polyair Ultimates on my Prado for the past two years, they have performed very well, and allow pressures up to 60psi so the Prado always sits level even when the camper is attached and provides a better ride especially on severely corrugated desert tracks or on the Madigan Line.
WHEEL ALIGNMENTS ARE IMPORTANT
While chatting with Kristian, it became apparent many of us don’t even link wheel alignments and towing.
“Very few people account for the added load in the vehicle and tow ball load which changes suspension height and therefore wheel alignment settings. The difference in ride height between unladen and fully loaded can often change your wheel alignment settings significantly resulting in early tyre wear and compromised handling and steering,” he said.
“If you’re setting up your vehicle for an extended trip away fully loaded, Ironman 4x4 suggest setting your alignment with the load on board to simulate the actual loaded ride height. Your wheel aligner can then fine-tune the camber, caster and toe with your vehicle in its final state of loaded ride height which means it will stay with those settings for the duration of your journey.”
CAMPER TRAILER OFFROAD SUSPENSION OPTIONS
There is no perfect solution for offroad camper trailers, which means different manufacturers choose the best one that suits their design. From leaf springs to airbags, independent to cross arm, they all have a place in the offroad market.
Leaf Spring suspension: This type of suspension was discovered just after the wheel and has changed little over the millennia. They are robust, perform admirably and are repairable on the side of a track. Getting the right setup to suit the weight of your camper is important for the ride comfort. However, they suffer from a lack of wheel travel and changing wheel camber caused by axle movement in harsh terrain. Some trailer manufacturers use shocks to help reduce oscillation.
Independent trailing arm suspension: Once only fitted to the top of the range campers, this form of suspension is now more affordable and therefore fitted to a majority of campers in Australia. With heavy-duty coils and shocks attached to the trailing arms, the wheels flex independently of each other, remain vertical throughout their travel and offer better ground clearance with no beam axle to contend with. This suspension package also offers an increase in ride comfort, another reason why it has become so popular with manufacturers.
Airbag suspension: With a setup similar to independent trailing arm suspension, the coils are replaced with airbags. Patriot Campers are the best-known trailers to have the airbag solution and the benefits of being able to change the airbag pressure independently allows self-levelling options, control of ride height and stiffness depending on the terrain. Considered to offer the smoothest ride in all conditions, this solution does require an on-board air compressor.
Cross Arm suspension: Currently unique to Terra Trek Campers who designed this system, the wheels are linked by adjustable trailing arms and cross-arms that pivot from the opposite sides of the camper. Heavy-duty coil springs with airbag and shocks control the wheel movement. This suspension set up is adjustable via the airbags or running longer travel springs provides excellent handling, long travel and is extremely durable.
IRONMAN 4X4 AND THE CAMPER INDUSTRY
I was pleasantly surprised when I asked Kristian if Ironman 4x4 were involved in the camper trailer industry. He explained, “We work closely with trailer manufactures to design and produce suspension specifically configured for each model of camper, ensuring correct levels of damping and spring rate to match the exact motion ratio and geometry the trailer possesses. Configuring a quality suspension setup takes a lot of knowledge and experience, that could only come from years of working in the suspension industry.
“Some camper trailer owners think that their suspension is doing it easy, but just because the trailer is smaller, and lighter doesn't mean it’s not working hard. We see many more overheated shocks on offroad camper trailers out there than we do in 4x4 vehicles.
“For this reason, many manufacturers choose to run twin shocks or a big bore shock design such as Ironman 4x4’s Foam Cell Pro as they offer higher oil volume that provides the shock greater capacity to disperse heat and resist shock fade.”