anti sway devices

Have to agree 100%.

I tow a 3500kg ATM caravan with a truck that has a GVM of 5,171kg.....a good ratio and also has heaps of power....can actually accelerate (even with the van on the back) quicker than a lot of standard 4x4s without any van.

In short two things matter: weight of tug v c'van and power to weight ratio.

I simply couldn't feel confident driving a light-ish and under-powered 4x4 whilst towing a large c'van (even though it may be "legal").

Similar problem but solved a lot cheaper. Used to tow a Chesney wind up with the Kingswood and had level riders on it. One trip we were moving house from Melbourne back to Sydney. Good on the Army. Three kids, a hundred (exaggeration) or so pot plants, two trunks and lots of clothes. The car way all over the place with the front feeling very very light.

Dropped in at a mates at Maroolbark for a farewell cuppa and he suggested that we rearrange the van with less weight on the tow bar.

Fixed it!

Sometimes I wonder at the weights that some say is on the tow bar.

Broodies initial post reminds me of exactly the same issue.

This is not a "told you so" Broodie. Just try it out mate. It can't hurt. May save some more funds for a carton or two of that favourite wine.

Phil

I believe that anti sway devices should be a last resort.

Firstly you need to find out why the rig is unstable. I had similar problems with my van when I upgraded to the D-Max. Went to Pedders to have an anti sway system installed at around $1200, the manager talked me out of it.

As a result I shortened the towbar shank by 30mm, reduced the ball weight by 30-40kg, re-adjusted the WDH and finally set all tires to 45PSI.

Not certain exactly which move fixed it but now rides much more stable than it did before.

Hi Kazza,
We never had a stability problem when we brought the van back from Melbourne Via Grafton in 7550 klm we never once had an issue with stability until we were coming down the hill at Northam and were over taken by a truck we were sitting on about 80 klm/phr because of the car in front of us, and when the semi went passed us at around 100klm/phr, that was when we got our first sway happening, not the most pleasant of feelings, the second time was coming down Greenmount and that was even worse, and that is why we are looking at stability control mainly because if my wife is driving like she does and this happens again it could be all over red rover, so kazza if you have any information on these stability control systems that you could share that would be extremely helpful.
thank you very much for your thoughts so far

Good morning TomH,
the weight of the van is 2648kg, weigh bridge checked and tested, towball weight on this trip was 275kg, gvm of the car 2995, six cylinder turbo diesel, towing capacity of the car is 3.5 tonnes, so the way I look at it I am in side the parameters of safe towing.
when we brought the van back from Victoria it was loaded exactly THE SAME, as we have not loaded it up for an extended touring as of yet, the van still has the same as when we brought her home, and we had no problems towing her whatso ever, that is why we are now looking at stability control devise cause I am damn sure I don't want this scenario happening again.
So my question to you is do you use a stability control device on your van if so what type and how effective is it.
thank you for your in put , and the checking of weight is an ongoing thing with me.
thank you

"the weight of the van is 2648kg, weigh bridge checked and tested, towball weight on this trip was 275kg, gvm of the car 2995, six cylinder turbo diesel, towing capacity of the car is 3.5 tonnes, so the way I look at it I am in side the parameters of safe towing."


All of the weights look right but there is one thing that is often overlooked by many people and that is the car manufacturers usually specify a maximum possible towing capacity and that is all. They do not say what it can tow and where.

A 3000kg van, a 3000 kg boat and a 3000 kg heavily constructed 3 metre long four wheel box trailer full of paving stones for example will all have different ball weights and handling characteristics. The car will handle some things in some conditions but not all things in all conditions.

Your main problem is a van of that size has more wind catching surface area down each side than many yachts have in their spinnakers. It can feel perfectly stable like you said until that one day when something knocks it far enough off its straight ahead course at the right speed. That is when you will go from feeling relaxed to having your hair standing on its end in a few seconds.

I agree with those who said you need a bigger tow car. It should be much heavier than the van with the longest possible wheel base and the shortest overhang behind the rear axle back to the tow ball.

All of these stability devices have their place and have no doubt saved many people but they are not infallible. They can not save the day every time no matter how much the van swings around..

Good mornig Phil,
just a quick question if you don't mind but your stability control was that on the van when you purchased it or was it retro fitted after purchase. You also say you don't notice it operating while travelling, so how sensitive are these anti sway systems. as I am still researching I am very interested in your reply.
Thank you for your input and time.

Alko ESC was standard equipment on our van purchased last year. But it looks like it would be fairly straightforward to install later. The main unit is screwed into the floor from underneath between the two axles. Power to it comes from the car via the red anderson plug and then it is also wired into the caravan's brakes. The red anderson plug has its own circuit on the car - directly off the cranking battery via a 30A circuit breaker. The LED lights that tell you it is ready are screwed onto the inside of the drawbar.

Not really sure how sensitive these systems are - I've never felt like the caravan brakes have come on while driving along. On rare occasions going through a gutter or whatever it is possible the brakes got applied for a short time because the caravan rocked from side to side.
Alko have a lot of literature on their website regarding fitment to existing caravans, so have a read:
http://alkoesc.com.au/for-existing-caravans/key-considerations-faq/
There is an impressive video and other info on youtube:
https://www.youtube.com/results?search_query=Alko+ESC
Alko also supply their manuals online:
http://alkoesc.com.au/technical-literature/

And I have no affiliation - its purely what came with our caravan.

This came in the email:
Magazine article on sway - probably by Collyn Rivers

Hi Bantam,
our suspension system is a simplicity suspension and it does not have shock absorbers and from what I have seen of a few caravans with independent suspension it beats me how with the angle of the shock absorbers that most of the independent systems use, it defies belief that the van would get any benefit from the shockies at all. that is why I discounted the independent suspension system when we had the van built and went for the simplicity, old technology but tried and tested, no shockies to wear out going down the types of roads that we travel
But the question I must ask is do you have a anti sway system fitted to your van if so which system.
thank you

I concur with BH3's comments, this is the first time I have ever heard that adding shockies will stabilise a caravan.

In answer to your question We didnt have nor need anti sway Van had a ballweight of 300kg and we had a WDH that brought the rig pretty level. Spent quite a bit of time on the west and never had any trouble with sway when passing or being passed by roadtrains. The only time we did was coming from Esperance to Norseman in a strong crosswind. Had to use nearly a quarter of lock to keep it all straight and it actually wore the Cruisers tyres on the inside on one side and the outside on the other. Still wasnt hard to control though, As others have said go over the rig and see what can be improved as Anti sway is an ambulance at the bottom of the cliff solution.
You need to prevent it from starting not prevent it after it starts.

HI TomH,
that is my argument as well, it is only a new van and has been towed from Melbourne to Grafton in NSW, and back to perth over some pretty ordinary roads we have been overtaken countless times by large trucks and road trains. and like you never had a towing issue until last Friday, we will probably never have a towing issue again but I want to err on the side of caution as my wife drives the rig too and does not have the experience that I do. hence the search for the best anti sway system available

The simple fact MUST be faced ..... ANY spring system without damping WILL oscillate. ..... This is simple physics and can not be avoided.
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People continue to dismiss the lack of shock absorbers (or more correctly suspension dampers) on trailers and caravans as insignificant.
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ALL trailers without shock absorbers or a suspensions with significant inherant damping WILL oscillate If there is sufficient source of excitation.
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If that trailer is a short low box trailer, significantly lighter than the tow vehicle it will not cause any stability issues , it will just bounce up and down with little harm...... IF however it is a long, high centre of gravity trailer like a caravan, towed by a vehicle close to the trailer weight it can become a very big problem very quickly.
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The majority of trailer sway incidents are caused pretty much entirely by undamped spring systems.
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A road incident, (many times a windage incident) causes the trailer to deflect ..... compress the springs on one side and extend on the other ........then because there is little or no damping in the system ...... the trailer hops from one side to the other as the undamped springs compress and expand ....... get the weight, spring rate, speed and lengths right ....... resonance occurs and the sway gets worse and worse till the combination overturns ...... there are many utube vids that show exactly this.
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If the suspension had sufficient damping .... as pretty much all other road vehicles except trailers are required to have by law ...... the suspension would deflect and rapidly return to the normal at rest situation in 1, 2 or at worst 3 cycles.
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Many factory standard road vehicles have significantly inclined shock absorbers ..... as much as 15 or 20 degrees ...... yes some of the trailer suspensions have shock absorbers at angles much steeper than preferable...BUT ... as long as the shock absorber is not starved for fluid it will continue to function as designed ..... most of the off road shock absorbers are specifically designed to continue to function at considerable angles.
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Yes there is the issue of mechanical dis-advantage with dramatically angled shock absorbers ...... IF the shock absorber does not travel in the same or similar path to the suspension, there will be a mechanical disadvantage and a reduction in the damping effect.
If the shock absorber is angled at 45 degrees to the suspension path ( not vertical) the mechanical advantage will be 1.2:1 ..... if the shock absorber is at 60 degrees to the suspension path, the mechanical disadvantage (and the reduction in damping) will be 2:1.
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BUT ...... and the is a VERY BIG BUT ....... there IS STILL DAMPING where there would otherwise be NONE.
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If shock absorbers tolerant of working at angles and with sufficient damping where used to compensate for the mechanical disadvantage, a very effectively damped suspension can result ..... this is why many off road independent suspensions have very large shock absorbers or double shock absorbers.
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Truth is .... quite small amounts of damping can considerably improve the stability of trailers and caravans .... it's not like we are trying to achive the wheel control that is needed to achieve expected ride and handling in a modern road car ...... we just need sufficient damping to stop the trailer oscillating and becoming critically unstable.
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People can disregard the elephant in the room issue of lack of suspension damping on trailers and caravans.
But the fact remains, no other road vehicle is legal without sufficient suspension damping.
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OH BTW .... compared to all the other gadgets, shock absorbers are very cheap.
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cheers

Cheers

My first van was a Roadstar Voyager 4000 21ft which had tandem Simplicity suspension and was as steady as a rock. I even had its ATM upped by 300kg to 2800kg and it rode as good as gold. Even when it had a tyre blow it didnt wander around.
Perhaps the OP altered the loading between trips or maybe added some things on the rear bumper which altered things.
Hard to say. I note in his photo it is a Roadstar so how did that travel compared to the new one. First thingI would do is fit an HR towbar if it hasnt got one already ( even if you dont fit a WDH). Far stronger bar.

Then I would borrow or buy a suitable WDH and see how it goes. If the van is inherently stable that should be enough.
If you need more the van has other stabilty problems built in.

You say it removed the steering weight from your front wheels which is a classic case of the need for a WDH to stop it pitching when going downhill and in general..

Hi Tom,
Our first van was 1995 Roadstar voyager, simplicity suspension and towed like it was not there and that was behind out current vehicle. We sold it only because she was getting a bit long in the tooth to be towing her down the roads that we like to travel also she didn't have the ground clearance that the new one has, that is the main reason that the new one has the simplicity suspension under her.. the hr tow hitch and tow bar were the first things put on the vehicle from new.
As for the new van and this new tendency to have a mind of its own doesn't faze me to much when I am driving but if my wife is driving and this happens again we could be in the proverbial
. Nissan have told me not to use a wdh as it tends to interfere with the traction control , and also with the independent suspension on the back wheels they also throw the wheel alignment out for the rear tyres, and I can attest to that as I am replacing rear tyres every time we do long trips and come home it is back to the tyre shop for new rear tyres.
you know we never had this problem with the Roadstar, go figure, and right about now I wish I had the old girl in the driveway. Any way anti sway system is going to have to be fitted.

Hi Ron,
thank you very much for the information, as you stated a lot of reading but I have finally finished reading the articles, I actually learnt some things I didn't know so a big thank you.
but it still doesn't solve my sway control issue and it is going to have to be fitted just to give me peace of mind for when the love of my life, my wife is driving, as I do like my rest periods.
Ron thank you very much

note one small line in the Colin Rivers article that some may pass over .

"Inadequate or non-existent spring damping can thus prejudice electronic stability systems that rely totally on caravan braking."

As for the question of what has changed ...... perhaps nothing changed except circumstance.

There is no escaping the fact that ALL rear hitched centre axle trailers are fundamentally unstable ...it's just a fact of design and phisics ..... this is why the "pig trailer as it is called is very much unfavoured in heavy transport.

Like any fundamentally unstable stable system, it can appear to be very stable or have large stable sections in its behaviour.

BUT when that system is placed in circumstance outside its stable behaviour it's true nature can be revealed dramaticly.

If that system ( trailer and tow vehicle) is poorly designed it can transition from stable to very unstable very rapidly and with vengance.

We can stabilise these Fundamentally unstable trailers to a point where their behaviour is predictable and they do not transition quickly and unpredictably from stable to unstable ... and thus are not a danger on the road.

But we must first recognise that they are fundamentally unstable.

Many people fail to grasp this fundamentally unpredictable nature and can not understand why something that towed so well for thousands of Km, suddenly became a problem.

Pretty much every single rear hitched caravan would become critically unstable and overturn or jackknife on good road and in good weather given the right stimulous.

GOOD Spring damping or shock absorbers on both the car and the trailer are one of the things that can dramatically improve stability and significantly reduce the tendancy to transition from stable to critically unstable.

All the other factors remain.

cheers

However in the OP it says that the truck going past removed weight from the tugs front wheels which alludes to a heavy ball weight becoming heavier due to dynamic forces and could be corrected with WDH.
Despite Nissan saying they shouldnt be used there are discussions on caravan forums (which I posted a link to) that contradict that. Also you say you are wearing tyres out fast now which to me also suggests too high a ball weight bearing down on mainly the back axle. A WDH will spread some of that weight and may help tyre wear. Have never ever heard of a WDH affecting traction control on ANY vehicle and lots have it these days I would ask them to explain how does it do that.

Hi Tom,
I am happy with the set up of the van as it is in relation to our tow vehicle, and as you know and everyone that has answered on this topic so far has all got different views on what is required to be done to stop or minimise the sway, I may tow the van another 10000klms, and never have this happen again, should I take that risk while my wife is driving, I personally don't think so, not when you consider the height of the van and the length, I in all fair conscious, and consideration of my wifes driving ability although very sound is very inexperienced with towing and her time behind the wheel with this van has been very limited. As you know you get something new hooked on the back of the vehicle it takes a while to get used to its movement behind you. yes you are dead right I am dead keen on an esc system, that is why I have asked the question to get the right one for our van and what and how we use our van. the set up is not the issue it is the unexpected that is, and me I don't like suprises while towing.
your thoughts are greatly appreciated, and very sound and make me think thank you very much.

do you have your brake controller in a position where you can easily reach and manually brake the trailer only?

Hi Bantam,
yes the controller is in a position to operate manually that is what got us under control faster than otherwise and took the g forces from the van, but if my wife had been driving the out come could have been a lot different. that is the reason we are looking into anti sway devices. Bantam thank you very much for your input it has been enlightening.