Car Advice

What is a weight distribution hitch and how does it work?

When it comes to towing heavy loads a weight distribution hitch can help to stabilise your trailer and towing vehicle, but what is a weight distribution hitch and how does it work?

There are a lot of myths around weight distribution hitches, so let’s start by dealing with the big one. And that is that a weight distribution hitch allows you to tow more because it transfers weight. It doesn’t; fitting a weight distribution hitch doesn’t allow you to tow more than your vehicle’s specified limit.

What happens when you connect a trailer?

When you hook uop a trailer to your towing vehicle weight is transferred onto the towbar, this is referred to as the towball download. If you’re towing a trailer at your vehicle’s maximum allowed towing capacity you’ll have a lot of weight bearing down on the towbar which then puts pressure on the rear axle, causing the vehicle to ride with a rear down, nose up attitude and the trailer to be dragged in a nose-down and rear-up fashion.

This is generally becomes an issue when your trailer weighs around 50% of your vehicle. But a poorly loaded trailer weighing much less than that can also cause issues with the towing vehicle. For instance, if your vehicle has a towball download of 350kg but the towball download being applied by the trailer because of poor loading is 400kg then you have a problem.

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Why is it bad to overload the towball?

Because, as mentioned, you get an imbalanced towing profile when can cause all sorts of problems, from reduced braking, steering and vision to increased and unnecessary wear and tear on your vehicle. But, worst of all, it can also increase the risk of trailer sway which is when your trailer begins to wag from side to side. This is both frightening for the driver and potentially dangerous.

How do I weigh the towball weight of my trailer?

There are a couple of ways to do this, you can use the bathroom scale method which I’m not a fan of because there’s too fiddling around involved and you can’t always be sure of the accuracy. The best way is to purchase a dedicated ball weight scale. To get an accurate measurement you’ll need to weigh your trailer’s towball download when empty and again when loaded as if you were heading away with it. Do this well before heading off with the trailer to ensure you’ve got plenty of time to make adjustments as needed.

Weight distribution hitch explained

How do I know I need a weight distribution hitch?

Ideally, you’ll be considering a weight distribution hitch if your trailer is around half the weight of your towing vehicle. Any more than that and you need a weight distribution hitch for trailer stability.

Can all towbars take a weight distribution hitch?

No. You need to check with the manufacturer of your vehicle, if it’s a factory fitted towbar, or the towbar maker if an after-market addition, about fitting a weight distribution hitch. Also, if you haven’t purchased a factory fit towbar then you need to check what the manufacturer says about maximum braked towing capacity. Many car makers list a reduced amount if not using a factory towbar.

Weight distribution hitch explained

What is a weight distribution hitch?

These are a set of spring bars that are fitted to the trailer’s drawbar. Once fitted and adjusted they create a lever that spreads the weight but not the mass being applied to the towbar and rear of the vehicle evenly across the axles of your tow vehicle and trailer. This means that the weights being applied remain identical, so, if the towball download was 300kg to begin with it will still be 300kg after the weight distribution hitch has been fitted. This means the weight distribution hitch spreads the applied weight but doesn’t change the mass.

By spreading the weight your tow vehicle and trailer to sit level and thus reduce the risk of trailer sway and ensure you have proper control over your towing vehicle. It’s a clever system and the action of how it works is often likened to raising a wheelbarrow via the handles or by pushing down on a set of scales while standing behind it.

So a weight distribution hitch solves all problems?

Not quite. The bars can reduce the turning circle of your rig and while your vehicle and trailer might be sitting level and sway potential is reduced it’s not eliminated. And that’s why many people also fit a sway controller too but we’ll look at that in another article.

Want to know more?

The aim of this article was to dispel the myth that fitting a weight distribution hitch allows you to tow more. It doesn’t. It just ensures the weight your towing is evenly spread across the trailer and towing vehicle. There are a couple of different types and brands of weight distribution hitch, and some are designed for certain types of drawbar. And, depending on the height of your vehicle and trailer, you may need to fit an adjustable towbar. Again, you’ll need to check with your vehicle manufacturer to see if this affects the maximum braked towing capacity of your vehicle.


Isaac Bober

Isaac Bober

Isaac Bober was born in the shadow of Mount Panorama in Bathurst and, so, it was inevitable he’d fall into work as a motoring writer. He began his motoring career in 2000 reviewing commercial vehicles, before becoming editor of Caravan & Motorhome magazine. He then moved to MOTOR Magazine before going freelance and contributing to Overlander 4WD, 4×4 Australia, TopGear Australia, Men’s Health, Men’s Fitness, The Australian, CARSguide, and many more.