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Roothy learns the importance of installing a weight distribution hitch.

Words and photography by John Rooth

So where do you deal with the weight distribution hitch? Does it come under our caravan or our tow vehicle project columns? I guess it really should sit in between but because that’s not possible, we’ll call it part of the tow vehicle series instead.

Why? Because a good weight distribution hitch – and Haymen Reese’s are the best in the world – not only makes all the difference to a tow vehicle’s driving manners, it saves a lot of unnecessary wear on tyres and suspension too.

Big claims, but until you’ve experienced the difference between a well set up WD hitch and a naked A-frame it can be hard to appreciate just how radically the tension on a couple of springs can affect the entire rig.

So what sort of caravans and tow vehicles should be using a weight distribution hitch? Not so long ago they were almost the exclusive preserve of the so called heavyweight brigade – the vans that weighed a couple of tonnes or more with too much of that sitting on the ball. Without WD hitches these things were un-towable but the fact is that virtually any trailer over the un-braked limit (750kg) will benefit from a weight distributing hitch.

But I hadn’t planned on investing in one for our project tow vehicle just yet because being a heavy four wheel drive fitted with ARB’s 50mm suspension rated to towing specs it shouldn’t – according to conventional wisdom – really require one. After all, Vicki’s only a 16 footer and at around 1.3 tonnes not much heavier than a camper trailer.

Yep, well ‘conventional wisdom’ was about as wrong as it can be. It all happened when I towed the old girl out to Caboolture Caravan Repairs for her final gas fitting and certification. Adrian took one look at the rig sitting on the road and said “where’s yer Haymen Reese?”

I asked him why he thought it was necessary. After all, it’s not as if the front wheels were pawing the ground or anything. The rig sat almost dead level. I say ‘almost’ because until Adrian broke out the tape measure I couldn’t see any appreciable ‘tail drop’ at all.

But it was there alright, and measurable.

“Johno,” said one of Australia’s most experienced caravan engineers, “just about every rig on the road could benefit from a weight distribution hitch. Many people never realise that and frankly, they don’t know what they’re missing. And then we see heaps of them that have been installed incorrectly and aren’t pulling their weight.”

Actually, Adrian didn’t say ‘incorrectly’ but ‘arse about face’ doesn’t sound near as technical. I knew what he meant though so I pushed the point and got his team to install one so we could see how it should be done. It was a Haymen Reese of course, the top blokes in the industry won’t recommend anything else.

Essentially a weight distributing hitch works by distributing the ball weight evenly to the front and rear axles of the tow vehicle. Without one, all the ball weight sits directly on the rear axle, pushing it down while at the same time reducing the weight on the front axle. This causes an imbalance in weight distribution on the tow vehicle which naturally affects stability and traction.

Yep, which is why good old ‘conventional wisdom’ said that, “whenever the tow vehicle’s front wheels are clawing the air, you need some weight distribution hitches”. Without them you won’t have steering or brakes – a couple of primary functions in the towing equation if ever there were some! But where conventional wisdom gets it wrong is that almost any weight on the ball directly affects the tow vehicle’s balance which in turn affects steering and traction. Transfer that weight and you restore the tow vehicle’s manners completely making towing as easy – and as safe - as driving solo.

But a weight distribution hitch has to be installed properly and that means taking into account the vehicle’s static (unloaded) heights back and front as well as the caravan’s. The ideal is to have both units stay at those solo levels once hitched up, which is the why Haymen Reese developed their unique adjustable ball mount. This unit allows the ball mount plate itself to be raised or lowered to suit any height differences between car and van and it can be tipped back or forwards too. This latter ability is crucial to getting the right load on the springs.

Fortunately Haymen Reese supply extensive fitting instructions as well as plenty of practical back up through their web pages. Plenty of things have to be taken into account like the positioning of the snap up brackets on the A-frame (allowing the chain to fall as vertically as possible) right down to the minimum number of links required for smooth operation – at least four, any less will pull too hard on the brackets under hard cornering.

It should be noted that while a weight distributing hitch can restore level to a towing rig, if you’re carrying a big and constant load in the rear of the tow vehicle you should still consider heavier rated springs or even air bags. The point is that if you start with the vehicle sagging at the rear you’re behind the stability eight ball no matter what.

But our 80’s already got good suspension rated slightly stiffer than standard at the rear to compensate for the fridge and all the paraphernalia a family of five requires. It handles very well, steers impeccably and is quite comfortable too. What the Haymen Reese unit did was maintain all those attributes with the van hitched up.

On the drive home the difference was immediately apparent because the Toyota handled exactly the same way it does solo. That made the entire rig feel more controllable – and it’s an excellently balanced chassis thanks to Adrian’s engineering – and took all the effort out of towing the caravan.

Almost all, it’s still necessary to remember that we’re twice as long as normal and a lot higher too. And we’ve got to stop for fuel more often and remember to put the step up and close the hatches. But what we don’t have to worry about is stability, whether it’s steering or under brakes. Thanks to a well fitted Haymen Reese weight distribution hitch, this rig tows as if all it’s doing is filling the mirror!