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How to Prevent Caravan Sway

by | Oct 10, 2017 | Trailer & Caravan Safety | 6 comments

How can I stop Caravan Sway is a great question. Learn why we recommend tow ball weights should be 5% to 7% on a tandem trailer and 7% to 10% on a single axle trailer.

The key to significantly reducing caravan sway is knowing the weight on your tow ball.

Once you have adjusted the weight in your caravan or boat trailer, then it is a simple matter to re-weigh your trailer coupling.

How do I test tow ball weight?

To start testing your caravan coupling weight, you need to purchase a Tow Ball Scale. These can be obtained by clicking this link.

Without a set, if tow ball scales, you have little information to balance your rig.

Another popular device to reduce caravan sway is a weight-distribution hitch, maybe a thing of the past.

Watch the video, and you will get an understanding of the dynamic forces called Yawl in a caravan.

The University of Bath UK has produced this video on caravan Yawl.

A yawl is a boat term used to describe the effect on weight and steerage.

A yawl describes the relationship between the location of weight and sway.

Weight distribution in the test model above dramatically affects the towing ability of the tow vehicle.

Your caravan has been perfectly balanced during manufacture and perfect driving stability.

So the question is, why is my caravan now so unstable above 80 kilometres per hours?

Excess caravan sway can have unintended consequences for your rig.

After you watch this next video, I will let you in on some towing secrets.

You have now witnessed how weight can affect your rig. You must have homes for your food, beer, camping equipment, generator, etc.

Some folks even have a weighbridge certificate.

Can I reduce Caravan Sway?

You may need to move it but do not yet know where it should go. Here is the calculation.

You know your ATM from your caravan nameplate. ATM = Chassis Weight + Payload (food,etc) + Tow Ball Weight.

Your tow bar will have a label for max downward pressure or S value or V value. Possibly not necessary but you should know what it is. Your car logbook has this value.

Your equation is Tow Ball weight should be between 5% to a max 10% where 5% is better than 10%. (5% of your ATM)

Example, tow ball weight of 110kg from a 2000kg caravan = 5.5% (tow ball weight / ATM) x 100%

Is weight too low or too high?

If your weight is too low, move the weight forward of your axles in your caravan.

If your weight is too high, move the weight back of your axles in your caravan.

When you have moved your weight, re-measure the head weight of your Coupling,

Understanding sway control may eliminate the need for weight distribution bars and sway control bars. Yes, I know

Yes, I know the industry loves its weight distribution bars; however, I am not a fan.

I fail to see any reason for transferring weight from and overloaded ‘A-frame’ onto the car rear suspension. I have many big question marks here.

The very best solution is weight redistribution over your caravan axles. As a result, this may require an axle upgrade from 10″ brakes to 12″ brakes.

Finally, tandem 50mm axles give you 4.5t capacity or 3.5t capacity with room for emergencies in rough terrain.

Here is another excellent article on caravan away.

Finally, electronic sway control is now available to purchase here.

The Sway control can eliminate the need for sway control arms and perhaps friction anti-sway couplings.

BMPRO Caravan Electronic Sway Controller

How can I stop Caravan Sway?


  1. Leanne

    Hi. Just wondering if van is fitted with electronic sway control and vehicle has its own sway control should the sway control in vehicle be turned off? 2021 Navara and RCC206 Regent Cruised. Asking because this is what dealership has told me after having issues with van swaying all over the place and very bumpy. They said both sway control is fighting against each other which is causing the issue. Never had this problem with other van we had but it did not have sway control on it. So for that reason kind of makes sense to me. Just want
    To know if
    Dealership is telling
    Me fibbs being a woman and all.

    • Kate

      Hi Leanne, it’s always good to double check information! Sway controllers installed on caravans and trailers are very sensitive, so having two different Sway Controllers active will cause some issues. I would recommend following the advice you received from the dealership here.

      Let us know if we can help with anything else!

  2. Sam Martin

    One thing most people are unaware of is the shift in dynamics when water is used in a van, the water tank empties (or fuel after a boat has been used) as it is used in the sink or ensuite. The ensuite in particlar can shift the weight initially as designed (not, mostly) but when the toilet is emptied at a van site an imbalance occurs. Therefore one needs to make sure their stocks of beer or wine gets moved to compensate. Use of tow ball scales before every hitch up of the van should be mandatory, they are a very cheap addition to necessary accessories.

  3. Bob Hinshelwood

    I recently purchased a new 17’6″ Billabong single axle caravan and towed it to Adelaide behind my 2002 turbo-diesel Prado. With both water tanks full (180 litres) the van weighed 2350 kgs. Weight was carefully distributed in the van and my Hayman Reese WDH was correctly set up. Tyre pressures were van – 50psi; Prado front- 38 psi; Prado rear- 42psi. I was alarmed that over a speed of 90kph the van sometime began to sway particularly going downhill. I was able to reduce the tendency to sway, but not eliminate it, by emptying the water tanks and reducing my tyre pressures to van- 46psi; Prado front-34psi; Prado rear-38psi. I had fitted new coil springs and shock absorbers to the Prado prior to my trip. In the past I have owned previous vans (single axle and lighter) but have not experienced sway to this extent.
    My Billabong is called a semi-off road model and only has leaf springs; as it is somewhat high off the ground and is quite heavy I wonder if it would handle better if it had dual axles?

    • Steve Wotherspoon

      Hello Bob, The answer is an electronic sway control unit that will automatically apply brakes in any sway situation.


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