How does a weight distribution hitch impact towing?

If you’ve ever been around a group of caravanners, the term WDH will probably have cropped up. But what is a WDH and do you need one?

WDH stands for Weight Distribution Hitch, but they’re also known as caravan ride levellers, a load distribution hitch, weight distribution bars, caravan levelling devices, and more, but they’re all more or less the same thing and operate on the same principles.

So, how do weight distribution hitches work? Fundamentally, a WDH is used to make a tow-car and its load (trailer, caravan, whatever) more stable by improving the weight distribution of the whole combination.

It does that by shifting some of the weight from the rear axle of the towing vehicle to the front axle, and some of the weight back on to the trailer’s axle(s).

In the process, this means the car will steer better and have more grip at the front wheels for braking. The safety implications of that are obvious.

Standard towing hitches for caravans do not have these features, so a WDH is something you need to specify when buying a van or purchase later.

The actual mechanics of the WDH are pretty straightforward. Fundamentally, you’re reducing the effect of the towball downweight applied by the trailer.

The WDH achieves this by providing a levering effect that raises the rear of the tow-car and lowers the front.

It does that via couplings and sprung torsion bars that link the car to the trailer yet still allow articulation at the tow-ball.

The actual mechanics of the WDH are pretty straightforward. Fundamentally, you’re reducing the effect of the towball downweight applied by the trailer. (Image: Sam Rawlings)

Most WDHs consist of a tow-ball tongue with the necessary attachment points, the torsion bars that run between the vehicle and trailer, adjustable chains to allow for different torsional loads, and a set of heavy-duty clamps that attach to the trailer’s A frame to accept the chains.

The mistake a lot of users make is to assume that a WDH hitch will also act as a sway control or caravan sway bars as they’re also known.

Certainly, by making the weight distribution of a towing combination better, a WDH makes every aspect of towing safer, but a specific cure for trailer sway they are not.

Some WDHs incorporate a sway controller into their design, but not all, so make sure you know what you’re buying.

There are no hard and fast rules about using a WDH or not, but there’s reasonable consensus out there that for caravan towing under about 2000kg or for a van less than five metres, there’s not really as much benefit from a WDH.

The average camper trailer should not really need a WDH. Also, the rule of thumb goes, if the tow-car’s front suspension doesn’t rise by more than about 20mm with the trailer hooked up, and the rear suspension doesn’t fall by at least the same 20mm, you don’t really need a WDH.

Even with a good WDH towing is not always hassle free.

On a 4WD with heavy suspension, you might find very little deflection of the suspension. Even then, repacking the caravan to better distribute the weight is your first step, rather than rushing out and buying a WDH.

Clearly, in a lot of cases, towing without weight distribution hitch is not the end of the world.

Some carmakers don’t recommend WDHs either, and, in fact, some go as far as to void your warranty if you use one and damage results.

Typically, some cars with air suspension aren’t recommended for a WDH, as the device messes up the car’s factory self-levelling function.

Even with a good WDH towing is not always hassle free, and the WDH itself imposes some considerations. One of these is noise, and the levers under tension can produce all sort of nasty creaks and groans.

A WDH is also not as good off-road where the greater articulation required at the towball generally rules them out.

The best weight distribution hitch Australia wide is the one that suits your car and trailer and is the one you know how to use effectively and safely.

That said, when it comes to the off-road oriented pin-type DO35 hitch problems off-road can be avoided by ensuring the towball maximum weight of 350kg is not exceeded and that full articulation is maintained.

The DO35 can be configured to work with at least two Hayman Reese WDHs.

It’s for the same articulation reasons that most WDH manufacturers recommend that you disconnect the WDH when crossing spoon drains or deep gutters and driveways. This is probably the single greatest bug-bear of the whole WDH experience.

You’ll often see online forums posing questions about Andersen weight distribution hitch problems, Alko hitch problems, McHitch problems and general questions about all brands including well-known gear such as Hayman Reese.

In many cases, the root causes of these problems lie in incorrect use and fitment of the hitch rather than any design or manufacturing flaw, and it’s an absolute fact that correctly and safely using a WDH hitch requires some familiarisation.

Which means, of course, that the best weight distribution hitch Australia wide is the one that suits your car and trailer and is the one you know how to use effectively and safely.

All the different types and brands use the same basic engineering principles, but a quality brand is crucial in something with the potential to completely change a vehicle’s dynamics. 

Don’t be afraid to ask question when shopping for a WDH and don’t be surprised if you get a lot of different opinions on the value of such a thing.