How to level a caravan or trailer
Do you have a caravan that drags its bum or sits nose down like a hot-rod on your tow vehicle? Time to get serious about setting up your rig – Here’s what you need to know to level a caravan or trailer.
Words and Images by Phil Lord: Getting your rig balanced is essential for towing safely. One of the critical aspects of rig balance is a level tow vehicle and van combination. A level vehicle and van, when hitched up, depends on several factors, but we are not going into that oft-trundled remedial effort, a Weight Distribution Hitch. The WDH has its place sure, but if you haven’t set up the rig, so it is level in the first place, a WDH is just a band-aid solution.
WHY BEING LEVEL MATTERS
Why do you need to have the vehicle and van level anyway? Balance. If the caravan is sitting either nose-up or nose-down when coupled up, its weight has shifted so that the rig’s dynamics have been affected – and often, severely.
Bear in mind that a level rig is only one part of a heady combination of factors that make up a safe, balanced rig. Things like adequate tow vehicle mass, a long tow vehicle wheelbase, correct tyre pressures, a long caravan coupling to wheelset measurement, proper unladen caravan weight distribution and finally correct vehicle and van payload distribution all factor in being able to tow your caravan down the road without it wanting to throw itself into the nearest field.
A caravan wheel set acts like a fulcrum, or pivot point. So, if the van is nose-up when hitched up, then there’s too much weight on the back of the van, resulting in poor towing dynamics. The back of the van will act as a pendulum, with the excess weight in this area causing the trailer to move from side to side.
When you have the opposite situation – the van is in a nose-down stance when coupled up – the weight of the van will have shifted too far forward, and this is also a recipe for a sway situation developing. This is magnified in the case where there’s a high towball download. That can cause the tow vehicle to lift too much at the front, reducing the balance and front tyre grip and therefore not only increasing the chance of sway but reducing the ability of the driver to steer and brake effectively.
Another problem with nose-down or nose-up attitude on the van is poor aerodynamics. Caravans are by their very nature are not the most aerodynamic of things, but with the frontal area altered by the incorrect balance, they can become even less aerodynamic, increasing the tow vehicle’s fuel consumption.
HOW TO CHECK YOUR RIG IS LEVEL
So how do you go about ensuring your rig is level? Start by making sure you’re not buying something mismatched, like, and this might be an extreme example, say, a tall off-road caravan hitched up to a low passenger vehicle. Even some 4WD utes have low-set towbars that will cause the van to be nose-down when hitched. At the other extreme, a tall, large 4WD US-style pickup hooked up to a road-going pop-top is likely to have the van with a nose-up attitude.
First off, you need to measure the van. With the van parked, uncoupled and on level ground, get a spirit level and place it on a horizontal part of the van such as the A-frame and adjust the jockey wheel until the spirit level indicates that the van is perfectly level. Confirm this by measuring one of the longitudinal chassis members at the front and then the rear of the van to ensure that the measurements are the same.
The van coupling and vehicle towball can now be measured to see if they are at the same height. It is difficult to get an exact, identical measuring point on coupling and towball, but a good point on the coupling is at the lowest lip of the 50mm coupling assembly and then on the corresponding point on the tow vehicle’s towball. You may need to hitch up the van to the vehicle to establish where to measure on the towball, so it matches the measurement you’re taking of the coupling height.
If your uncoupled heights have a difference of more than about 100mm, it suggests you may have a problem with accomplishing a level-riding rig. If you have measured the vehicle and van before buying either, you are in the fortunate position of considering whether you might need to go with another vehicle/van combination. If you’re sold on the combination or already own the rig, we’ll get to what you can do about it shortly.
According to Vehicle Standards Bulletin 1 (VSB1), the centre of the coupling must measure between 350mm and 420mm from the ground when the trailer is coupled to the tow vehicle. So, if your uncoupled measurements are outside of these, don’t worry about it yet because you’ll establish if you’re legal once you’ve hitched up the van.
Before hitching up the van to the vehicle, check the static suspension height of the tow vehicle. Measure from the centre point of the wheel or the lowest part of the rim to the lip of the wheel opening for both a front and rear wheel on the same side of the vehicle.
Then hitch up the van and repeat the measurements on the vehicle and check you do not have more than about 25mm droop at the rear or 25mm rise at the front. With the caravan hitched, check your spirit level and measure chassis rails again. A small difference in measured caravan chassis rail height (depending on the length of the van but say about around 30mm) won’t have a significant effect on balance, but if you see a difference of 50mm or more, it indicates a problem — time to do something about it.
LEVELLING UP YOUR RIG
The primary way to alter rig level is by changing the towbar tongue to an aftermarket one, either to one that offers multiple, adjustable height positions or a fixed tongue with a height corresponding to the one you require. Often caravanners will flip the towbar tongue to provide more (or less) height to better match the coupling, but you should only do that with proper advice from a towbar expert or the towbar’s manufacturer. Often the towbar tongue is only rated to take its maximum download force when in one position. A visible indication of this is when a towbar tongue has welds on the underside that will not allow a towball to be fitted if the tongue is flipped over.
With either an adjustable or fixed aftermarket towbar tongue set at what appears to be the correct height, you may still have unacceptable rear suspension droop (more than 25mm) on the tow vehicle. In this situation — as long as the tow vehicle’s front body rise measurement is no more than about 30mm — you need to establish whether towball download is excessive, by either measuring it with a set of kitchen scales, a dedicated towball download scale or at a public weighbridge. If the towball download is around seven to 10 per cent of the van’s weight, then all you may need to do is fit stiffer rear springs or airbag helper springs to the tow vehicle to level it out. If the tow vehicle’s nose is pointing towards the sky and you have a high TBM, then you need to consider repositioning load in the caravan and vehicle so that it is better balanced. Every vehicle and van combination is different, so again see independent expert advice to see what will work best in your situation.
WEIGHT DISTRIBUTION HITCHES ARE A GOOD IDEA, BUT…
The Weight Distribution Hitch (WDH) has taken on a mythical status in some Australian caravanning circles as the only safety item that guarantees your rig won’t sway its way into a roll-over. Some would suggest it would be suicidal to tow without one fitted.
While there is a place for the WDH, it is not the cure-all some suggest it is. A WDH exerts enormous forces on the caravan and vehicle chassis and especially on the vehicle towbar. In many cases, the caravan needs to be better balanced or is just too nose-heavy for the tow vehicle. In all cases, a WDH’s spring bars must be slackened before negotiating deviations in road surfaces such as spoon drains or steeply angles driveways – or it will impose loads on the vehicle and van it was not intended to impose and that can cause damage. If your caravan has a high towball download (more than around 250kg, or more than 15 per cent of total caravan weight), then you still have to ensure your rig is level, using the steps mentioned earlier, before attaching a WDH.