One of the quickest way you can tell if someone has set their 4WD and caravan (or any trailer for that matter) correctly for towing is to look at it parked on level ground, and to see if its all level.
If the rear of the car is angled down, or the front of the trailer is angled down, (or up) then it hasn’t been set up correctly, and the owners are at risk of either being over weight, illegal or greater chance of having an accident.
Of course, this is just a visual check, and there’s 7 other things you need to make sure you check too, which you can read about here; Simple Towing Guide.
There is no reason for people to be driving a setup with it not level, and the results can actually be quite dangerous. Often the remediation is as simple as turning the hitch upside down, or fitting some appropriate springs to the 4WD, or adjusting the tow ball weight so its more manageable.
Some setups are wrong from the get go though. Towing a full off road caravan with a vehicle that is much lower to the ground will require a hitch that sits up significantly higher than what the factory one does, and in many cases this will impede on rear doors opening, or tail gates opening without fouling on the hitch itself.
How do you make the trailer and tow vehicle level?
This is actually really simple. If you park both setups on flat ground, you can take measurements from the hitch to the ground on both the car and the trailer.
Get a spirit level on the drawbar of the trailer, and measure it when its sitting perfectly level, and then see where the car sits. If there is a difference, you need to do something about it.
Remember also that when you attach the trailer some of the weight is passed to the vehicle by way of tow ball weight, and it will lift the front of the vehicle up, and drop the rear down.
Your vehicle needs to be suitable for this, and if you are finding that the rear of your 4WD sags right down when you attach the trailer, you need to do something about it.
Why is it not level?
Below are the main culprits for a towing setup that is not level, and how you can fix it.
Incorrect rear springs
A lot of 4WD’s will not take a heavy tow ball weight very well, especially when loaded up with other gear. From the factory they are designed to be comfortable driving on the road with limited weight, and the way they do this is to run soft springs that don’t take too well to heavy loads.
When you put 200+kg of tow ball weight on the rear you’ll find the front of your 4WD will go up, and the rear will go down in a bad way.
This is a big problem, as it means you have limited suspension travel, excessive rear axle weight and as a result poor steering. In essence, it’s a recipe for disaster and you might even find your insurance isn’t valid as your vehicle isn’t legal, and roadworthy.
To fix this, you have a couple of options. The most common way is replace the rear springs with something that is suited to the task, and the second most common way is to install air bags. The latter uses bags that sit inside your springs, and help to take some of the load.
These are a great way to have a setup that will do variable loads without any issues. You can have the softness of normal suspension during the week, and for the once a month trip with the van you just pump the air bags up and they will take the load.
However, its imperative that you use the air bags sensibly. They do not increase your load carrying capacity, and if you use them for this, you will end up with a broken car. Also, even when you are not in need of the air bags, they must have some air in them (if they are in coil springs) as you can pinch the bag and damage it.
The safest way is to get your vehicle weighed, and to purchase springs that are suitable for the load you are carrying. The issue with this is that if you carry a heavy load sometimes, and nothing others you can end up with a vehicle that rides like its on bricks when empty.
Poor load distribution in the car
Your vehicle has a maximum weight that it can be, which is known as the GVM. This is everything in and on the vehicle including accessories, people, gear, fuel and also the tow ball weight. Your GVM is made up of two axle capacities, between the front and the rear.
The manufacturer expects that you balance your 4WD properly, and you don’t put all of the weight on the rear axle.
Despite this, many people do exactly that, and you end up with a lot of weight over the rear and very little over the front. This will cause the rear of your 4WD to sag, and give you the same results as above. You’ll have an overweight rear axle, poor steering, limited rear suspension and a disaster waiting to happen.
The rectification is simply to balance your load better, or to get different springs that suit the load (and are within the axle maximums!).
Too high of a tow ball weight
The amount of weight people have on their tow bars scares me, often. A lot of modern 4WD’s have a 350kg maximum tow ball weight, which is a huge amount of weight.
The thing that most people don’t realise is that because the distance from the rear axles to the tow bar is so long, you get leverage which increases the amount of weight you are applying to the rear axle.
350kg on the tow bar of many 4WD’s is closer to 500kg of weight applied to the rear axle, and that is an individual compliance you need to meet. 500kg on the rear axle without adding any extra gear, passengers or fuel can make your 4WD illegal super fast.
Either way, its important that the tow ball weight matches your vehicles capacities and also the trailer setup. In Australia, the general guide is somewhere between 6 – 12% of the trailer weight should be applied to the tow vehicle.
This gives you a good amount of stability without breaking anything, and can usually be achieved fairly easily. If it cannot be achieved, you have a design fault.
Incorrect height hitch
A hugely common way to have a towing setup that isn’t level is to start with a tow hitch that is the wrong height. I mentioned above of the need to take measurements of your trailers tow hitch on level ground, when the trailer is level, and then of your 4WD.
If the difference is more than about 50mm, you will have a major problem.
The thing that makes it even worse is the problem is exacerbated as the difference increases. The more you have to drop your trailer down on an angle, the more tow ball weight it applies to the tow vehicle, and the more the rear of the vehicle sags, which in turn applies even more tow ball weight.
By simply getting a hitch that keeps the 4WD and the trailer level you can hugely reduce the tow ball weight and sag, and keep everything in line and happy.
You can turn your hitch upside down if you thoroughly investigate the parts you have, and get confirmation its legal.
If you have a setup that does not sit level on a flat road when you are towing it, you should do something about it, as the poor weight distribution can have catastrophic consequences on, and off road.
Is your towing setup level? Did you have to make adjustments to get it there?