It’s not a secret that a caravan or any trailer for that matter, is inherently unbalanced.
You’ve got a set of wheels roughly halfway down the length of the caravan and up the pointy end a coupling that hooks up out in the breeze behind a tow vehicle.
No steering, no stability at all, on its own. That a van on the move can end up swinging like a pendulum to the point that it tips over both vehicle and van should surprise no-one.
So how to avoid this bit of physics theory becoming your nasty reality?
Here’s some advice to help camper van to avoid a roll-over…
If you’re about to buy a camper van, you should size up its inherent balance. What that means is, looking for errors in design that could upset the van’s balance.
Water tanks should be as close to the van’s axle as possible, and if there’s just one, just ahead of the axle. This is because when filled, the tank(s) can weigh 90kg-plus. Having that weight too far back, especially, can upset the balance.
Having two jerry cans full of diesel, a couple of off-road spare tyres and a bike rack full of bikes on a caravan’s rear bumper also does nothing to help proper balance.
In an ideal world, a caravan would be designed to carry heavy payload over or just ahead of the axles. That is just not practical, so inevitably most have a front or front tunnel boot. If you’re looking at a van that seems to have a lot of storage facility towards the back, you might think twice about buying it (or if you already have such a van, certainly not using it for heavy gear).
Ensure dog wags the tail
It’s not only good caravan design that helps avoid a roll-over. A tow vehicle that’s as heavy or heavier than the caravan helps to avoid the van pushing the tow vehicle around on the road.
A tow vehicle with a relatively long wheelbase and short rear axle-to-towball measurement will be more planted on the road and help to stop sway.
Full-size off-road vans sitting tall in some off-road situations can be exactly the right van to have, but you have to face the fact that such a van is more susceptible to sway.
Their higher centre of gravity will make them more prone to wind buffeting and their greater suspension travel will react more to sudden direction changes. A lower-slung pop-top will be not only more aerodynamic for fuel savings, but also more stable.
Store stuff properly
As mentioned above, you usually have the most storage space up front in a van. That doesn’t mean that you should put all your heavy gear there.
Try to put heavier items closer to the axles. Often there are storage options closer to the axles, such as under the front bed, or even in lower kitchen cabinets in the familiar centre-side kitchen set-ups.
Storing some gear on the floor over axles will help – although admittedly it’s often not practical to do this, and it might damage cabinetry and/or the gear you’re trying to store there if you don’t use soft padding to protect it all.
Half a tank of water sloshing around as you drive down the highway is only going to encourage sway. Keep the tanks either full or empty.
Watch your tyre pressures
If your tyre pressures are too low on the bitumen not only do you risk the tyres overheating and blowing out (there’s a big roll-over risk right there, especially for single-axle vans) but also the tyre will flex more and encourage sway.
Percentage rule isn’t gospel
That 10 to 15 per cent of a caravan’s weight should be on the towball is not a set-in-stone recommendation like it was 40 years ago.
These days, with vans up to around 2200kg, as low as seven percent tow ball mass is fine – all else being equal – and with a friction coupling, European vans get away with as little as five per cent.
Get a hold of a towball weight scale so you know exactly how much TBM your vehicle is lugging around.
WDH not a cure-all
Using a weight distribution hitch can be a band-aid fix if you haven’t sorted out balance issues.
On heavy off-road vans, you may have no choice if you need to get weight off the vehicle’s rear axle and onto the front when hitched up.
If your tow vehicle’s body settles more than around 25mm at the back axle, and/or the front rises by more than about the same amount, you need to look at either re-thinking your van’s payload balance, or fitting a WDH.
Using a WDH will aid stability, but it comes at a cost. The amount of stress imposed on the vehicle chassis/frame and towbar can be enormous.
If you check the WDH’s instructions, it will tell you that to avoid such damage, you are meant to disconnect the spring bars when driving over things like spoon drains or steeply angled driveways.
Know anyone who does this? Thought not.
The power of ESC
Trailer sway control and caravan stability control are both good active safety systems to avoid getting into a dangerous sway situation that leads to a roll-over.
However, if you have electric brakes, you already have a very good safety system right there. Activating full trailer braking at the brake controller if the van starts to sway will ‘stretch’ the rig out, slow everything down and hopefully stop the sway.
You have to be pretty quick though, and that’s where the ‘automatic’ systems (trailer sway and stability control) can really pay off.
Watch your speed
Even though in most states you can legally go as fast towing a van as everyone else does in their cars, it’s not a good idea.
Sticking to between 90-100km/h rather than cruising at 110km/h will help stop a sway situation from developing. Going even slower – well yes, that will work even better. Except that you will make travelling a lot more dangerous for you and everyone else.
You can’t stop people wanting to travel at the legal speed limit, and in stressful, time-poor situations drivers will take more risks to pass you, if you’re doing 70km/h in a 100km/h zone.
Equally, doing 70 or even 80km/h on the freeway means that you’re presenting other drivers with a 30-40km/h speed differential, which in some situations is a danger to safe traffic flow.
Beware of the wind
Large vehicles like trucks push a lot of air around them and can upset the stability of your rig. When you’re passing or being passed by a large vehicle on the highway, move your rig away as much as possible so that it’s less likely to be unsettled by the disturbed air.
The same applies to cross-winds; as you come out of a sheltered section of highway into a more open one, be prepared to slow down a little in case a blast of wind catches the side of the van.
Looking up at trees to see if they’re moving around can also give you the warning that you’ve got windy conditions ahead.
The thought of having a vehicle and caravan roll-over is every caravansary’s worst nightmare, but with the right preparation you can cut down the risk of that ever happening and get on with the fun stuff – enjoying your holiday.