In Sydney need advice instability when towing

[Glynhouse]

Looking for some advice,
Have just done Cairns to Sydney with a 3 tonne van on the back MY07 TDV6 Disco, now has 113000klms on it. Pulls like a dream but is definitely not stable on the road, very very susceptible to wind and passing vehicles, the van now has over 130K on it has always been very stable behind both a cruiser and Patrol.
Using a Mitchell Bros hitch and no WDH, definitely a lot more bouncy but that would be expected what was not expected is the twitchyness and the ducking and diving that it does on any road with and uneven surface or grooves in it.
I have replaced the front lower arms due to a knock and have had the wheels aligned twice trying to tighten up the steering, it is nothing out of the box without the van either.
Running OE wranglers on it 18" were new when I bought it at 88000 Kim's, wearing evenly and I would think less than 50% worn. So hoping for 60 or 70k from them.

Anyone got any suggestions ? Or where do I take it ?

DD

[outasight]

A couple of questions come to my mind ...

Is your car an airbag model or springs/shocks? You mentioned WDH, and of course if you have the airbag system you don't use them.

What ball weight has the van got when towed? I suspect it's either far too heavy or too light.

Regards,

Les.

[Graeme]

How many kms on the current shocks? They only last about 60K if doing any work.

[Glynhouse]

Air suspension and ball weight around 300kgs normally, tried to measure it before we left and got 280 but was doubtfully method, but that is about normall, has been to ;340kgs fully loaded when we lived in it.
Shockers are original, I am dubious about them that would explain some of the bouncing but not the flightyness,
Van has always towed fine never been a problem, we bought it new.

DD

[TerryO]

Your only two hours drive away from Goulburn, why not come down here and try towing your van with my D3 and see how that goes?

Mine is set up with a Mitch Hitch as well. My guess is your Wrangler tyres and possibly your shocks are causing your issues.

Your welcome to stay the night on the property if that makes things easier.

PM me if you like.

[discotwinturbo]

It might be weight. My D4 is airbag equipped and how 3.5 tonne horse float causes the rear of the disco to wallow. It's 340kgs. My Toaureg with wdh is smooth with the same load.

The airbags try to imitate wdh but will never be as smooth for my tow setup.

LR videos on youtube showing it towing 3.5 tonne, shows the wallowing too....it must be an airbag thing with heavy weight.

Maybe need to move more weight to the rear....I can't move our horses any further back to help my problem.

Brett....

[TerryO]

I would have thought the more weight you put on the rear of the trailer the more it wallows, not less.

Anyway DD the offer is there.

[discotwinturbo]

I would have thought the more weight you put on the rear of the trailer the more it wallows, not less.

Anyway DD the offer is there.

Probably does. I was just basing on transferring weight from the hitch away using the wdh on my Touareg which seems to cure it for that car.

Your offer sounds the best option.

Brett....

[Glynhouse]

Thanks Terry might just do that, we intended taking a week off from baby sitting from the 25th on and heading your way, will contact you if it works out.
It is not he wallowing that worries me it is the directional instability, and the sever wind affect, something we have not had before with other tow vehicles, is your Disco any less stable than your Touraeg Brett ? Direction wise and does it track in wheel ruts ?
Camped next to a guy with a Touraeg loves it tows a 22 foot van, unfortunately 2 guys with Discos here love the power but won't admit it but I get the feeling not much better than mine, a handful on the road.
The van does tow well behind other brands of tug, so it is Disco specific, will find out if we get up to Terry's

DD

[TerryO]

All be it our van is only 2.5 ton the D3 tows it well. So lets see how it tows your van and then may be fit my rims and tyres to your D3 and then see now your D3 handles with different tyres.

[Yorkie]

Could it be tyre pressures on tug and tow, or tyre type on tug, would an LT be more suited due to the big weights involved?

[discotwinturbo]

Thanks Terry might just do that, we intended taking a week off from baby sitting from the 25th on and heading your way, will contact you if it works out.
It is not he wallowing that worries me it is the directional instability, and the sever wind affect, something we have not had before with other tow vehicles, is your Disco any less stable than your Touraeg Brett ? Direction wise and does it track in wheel ruts ?
Camped next to a guy with a Touraeg loves it tows a 22 foot van, unfortunately 2 guys with Discos here love the power but won't admit it but I get the feeling not much better than mine, a handful on the road.
The van does tow well behind other brands of tug, so it is Disco specific, will find out if we get up to Terry's

DD

Hi DD,

With the heavy weight the Touareg is much more stable. The float is wide and definitely not in the wheel tracks of either car.
My wife noticed the difference when she first towed with the disco. But the disco is more safe to set up and she hates the wdh....when taking it off it can be scary for a 60kg girl.
The Touareg only occasional tows the float now, and when we do use it, it is definitely more pleasurable. The disco is not painful, but requires more concentration.
Our 2.5 tonne caravan, behind the disco is perfectly fine with only a small amount of wallowing. When we towed it with the Touareg it does not have a wdh and feels about the same.
Either vehicle has no swaying.
I put it down to the heavy towball weight. It seems that the airbags cannot possible replace how a wdh hitch works.
Brett....

[Graeme]

All be it our van is only 2.5 ton the D3 tows it well. So lets see how it tows your van and then may be fit my rims and tyres to your D3 and then see now your D3 handles with different tyres.An opportunity to compare towing the van with newish shocks too.

[TerryO]

The ride with the new Delphi shocks is way better than it was with the stuffed Koni's but I do not believe that they are as good as the standard OEM shocks even though both sets are made by the same company.

But yes that is some thing else that can be compared.

[Graeme]

I concur re these shocks and the a/m Delphis are way so much better than worn-out LRs too in the area of general stability. My vehicle was so untidy with the LRs after 60K then became well-behaved again with the Delphis. I much preferred the genuine D3s for their better slow speed damping when new. D4's have more slow speed damping so for towing I would use them rather than D3s - some people even use D4 shocks when not towing!

[Fatso]

Couple of things to think about , is the center of towball to tow bar attatchment the correct distance , ie the longer the moment from the original attatch point the more sway can be introduced by the van , is your towball weight included in your max gross wieght or max rear axle wieght , are the tyre pressres correct for the extra load . Al

[Glynhouse]

Quick update, had the D3 out to Davis Performance Landys this week, they gave it the once over - very quickly, as a result it is having new rear shocks, the bushes on the rear sway bar, and front tie rod ends which weren't done when the new control arms were fitted and a good wheel alignment. They were appalled at the way it drove, so here's hoping.

Was a bit surprised at the cost, so went through this site carefully and have had 3 prices for the same work from folk recommended on here, and Davis were the most reasonable by quite a distance.

Going up to visit TerryO on the weekend but no real point in comparing vehicles till mine is fixed. But thanks all the same Terry the offer was much appreciated.

DD

[White D4]

I tow a 25ft 3.5t dirt road van with my D4, first experience was terrible, Disco was all over the place quite a scary experience, I hated it and so did the wife. Disco was nearly sold

I then changed a few things
1. Put a good set of A/T LT tyres 10 ply on the van and pumped to 50psi
2. Ran 50psi in the LT Continental Cross contact A/T on the car
3. Ran 35psi in the front

Difference in stability was amazing, just came back from a 2000km trip to Qld, sat on 90kmph without the scary stuff and even hit close 100 a couple of times and no issue, even with trucks passing.

But still feel the fleetingness of the airbags so you have to concentrate allot more.

I have ordered a new LC200 through the business as the deal was much better than LR could offer but will keep the disco for the wife, but the WDH on the LC with a van of my size will ride better from the tests drives I have done.

Still love my disco but..

[Redback]

I had quite the opposite situation when I towed our daughters Amarok on a car trailer from Myrtleford to Sheperton(145Ks) last Xmas, all up about 3.5tonne, 860kg trailer, 2.5 tonne Amarok with a full load of wood in the back, also the trailer had led lights so the car didn't recognise there was a trailer on the back.

Never had an issue, sat on 90kph and on the freeway 100kph, 46psi in the rear, 36psi front, trailer tyre pressurs were what ever the hire place put in, I was amazed how stable it was AND, as a bonus 15l/100k for the trip:D

Love our D4,

Baz.

[discotwinturbo]

I had quite the opposite situation when I towed our daughters Amarok on a car trailer from Myrtleford to Sheperton(145Ks) last Xmas, all up about 3.5tonne, 860kg trailer, 2.5 tonne Amarok with a full load of wood in the back, also the trailer had led lights so the car didn't recognise there was a trailer on the back.

Never had an issue, sat on 90kph and on the freeway 100kph, 46psi in the rear, 36psi front, trailer tyre pressurs were what ever the hire place put in, I was amazed how stable it was AND, as a bonus 15l/100k for the trip:D

Love our D4,

Baz.

Your economy is great.
I regularly tow a 3.5 tonne triple axle horse float, and freeway sees it had 17.5 on the trip computer, while taking into my constant 1.9-2.0 lp 100 difference puts it at 19.5....my Touareg does the same job at 16.

Brett.....

[TerryO]

Your economy is great.
I regularly tow a 3.5 tonne triple axle horse float, and freeway sees it had 17.5 on the trip computer, whine taking into my constant 1.9-2.0 lp 100 difference puts it at 19.5....my Touareg does the same job at 16.

Brett.....


Yeah but Tworags are sooky girly cars that get scared when you go off road. ...:wasntme:

[gghaggis]

Your economy is great.
I regularly tow a 3.5 tonne triple axle horse float, and freeway sees it had 17.5 on the trip computer, whine taking into my constant 1.9-2.0 lp 100 difference puts it at 19.5....my Touareg does the same job at 16.

Brett.....

Best to measure it - with the tyres you've got on, your trip computer could actually be pessimistic!

And of course, your D4 is carrying one or two accessories ........ ;)

Cheers,

Gordon

[Glynhouse]

I have all the fuel dockets for this trip but have not done the sums ? !
Will post when I get home will be a total of over 7000 Kim's. 90% with a 3 tonne van on the back. Computer went up to 16.5 with a strong head wind but normally reads 14.- 14.5 with the van at anywhere from 85 to 95 kph.

Another question, the recommendation is that I replace the rear shockers only, at this stage the front appear O.K. This vehicle used to tow a 2 horse float every weekend before I bought it, so that could explain it, done 115000klms now, I did suspect the rears were not good from the trip we did to the N.T.
Looks like the air con compressor needs replacing as well so the budget is feeling the strain just at present.

DD

[discotwinturbo]

Best to measure it - with the tyres you've got on, your trip computer could actually be pessimistic!

And of course, your D4 is carrying one or two accessories ........ ;)

Cheers,

Gordon

It does carry a bit...Including me. When I tow with the horse float I use the factory rims and tyres.

Brett....

[discotwinturbo]

Yeah but Tworags are sooky girly cars that get scared when you go off road. ...:wasntme:

I get a bit ....just a bit of flex in my Touareg!

A bit off topic ;-)

Brett....

[Ghind]

I have a 1995 p38 range rover with air suspension and a 27ft caravan which is fully loaded both ball weight and overall

I've towed this van many 10s of thousands of kms

My car is rated for a 350kg ball weight and 3500kg towing. The same rubbish about wdh was said about my car

I cannot believe that lr would say you must not use a wdh.

A wdh would fix your stability problems

I can't imagine any reason you couldn't use one and I bet lets of people do. You might look into this further as to why you "can't". I was thinking of buying an lr4 but won't if you can't use a wdh.

Imagine a kids see-saw. Child sits on one end and the other end gets lifted into the air

Same with a car. Your rear axle is the pivot point and the tow bar is the child's seat on the end.

Your hitch is behind the rear axle. You put weight on a hitch and it levers weight OFF the front axle.

If you put 350kg on a hitch that is one metre behind the rear axle and the front axle is 3m forward of the rear axle you will take approx 120kg off the front axle. This will also go onto the rear axle

This reduced weight on the front axle will reduce traction on the front wheels and promote sway

Airbags will hold the car level but they won't change weight distribution

My caravan is scary without wdh and travels brilliantly with it

Some people may argue that airbags do the same job as a wdh. They don't and can't. This is an engineering fact. Airbags can make a car level. They cannot take weight off a rear axle and transfer it to the front.

Getting your tow ball as close to the rear axle as possible also helps a lot as does removing all slop/making it a tight fit

My hayman Reese tongue stuck out further than needed so we drilled a new pin hole so that it could be slid all the way in.

My thought - try it with a wdh and let us know.

Greg

[sheerluck]

...........I cannot believe that lr would say you must not use a wdh.

A wdh would fix your stability problems.......

Welcome, and an immensely brave first post.

It states very clearly in the handbook for both the D3 and D4 that a weight distribution device must not be used. The theory is that the onboard systems can detect trailer sway, and are able to correct it.

In the case of the OP of this thread, it turned out to be a suspension defect, a WDH would not have helped.

As for not buying a Discovery 4 on the basis that you can't use a WDH with it, that's like going to Dell and saying that you won't buy one of their PCs because you can't buy one with a 5.25" floppy drive.

[mowog]

I have a 1995 p38 range rover with air suspension and a 27ft caravan which is fully loaded both ball weight and overall

My thought - try it with a wdh and let us know.

Greg

Towing stability issues with a D3/D4 are almost always a problem with the van set-up. The next most common cause is the driver creating a sway by over correcting when the feel movement.

Suggesting that some use a WDH against recommendations is foolish. Below is a forum that welcomes poor advice head over there.

Caravaners Forum • Index page (http://www.caravanersforum.com/index.php)

[FeatherWeightDriver]

WDH

A what now? :wasntme:

I don't do much towing of really heavy stuff so didn't know what that was, hopefully others find this video useful to explain what it does and more importantly how it works

Hensley Arrow Sway Control Hitch - YouTube

PS: Now I still don't understand how it works, but see what it does - normally it takes this for me to learn: :bat:

[Graeme]

Welcome, and an immensely brave first post.

It states very clearly in the handbook for both the D3 and D4 that a weight distribution device must not be used.My handbook says "should", not "must". As I've stated before, I would use one in a flash if towing something heavy but then I make my own rules sometimes.

[Graeme]

I can't imagine any reason you couldn't use one and I bet lets of people do. You might look into this further as to why you "can't". I was thinking of buying an lr4 but won't if you can't use a wdh.The thing to watch is to not transfer too much weight. Adjusting the hitch with the vehicle being able to level will prevent any indication as to how much weight is being transferred.

[Glynhouse]

Mine also says "should not", we will see what happens when the rear end is done up on Tuesday, but I have every intention of trying the WDH when I get back home.
I have had this vehicle to a few recommended shops here in Sydney and when asked about using it the reply was " Why not " I wont give names, but as it is out of warranty and the suspension is not very responsive time wise, they could see no reason not to use it.

Will keep you posted on developments. Nearly 3000klms home first so will have a fair idea of how it is before I play.

I can see no difficulty in getting the tension right, just do it with the door open or key off when the suspension is inactive, then probably back it off a little to allow the suspension to think it is doing the job.

DD




My handbook says "should", not "must". As I've stated before, I would use one in a flash if towing something heavy but then I make my own rules sometimes.

[Graeme]

The vehicle will still level down with a door open etc. However when the people at Overlander Magazine set-up a D3 with a WDH for a caravan tow test comparison it took them only a couple of adjustments to get it right by the seat-of-the-pants method. Oh yes, the D3 was subsequently given the nod as the best tow vehicle of the group being tested.

[gghaggis]

Mine also says "should not", we will see what happens when the rear end is done up on Tuesday, but I have every intention of trying the WDH when I get back home.

DD

You might get away with this if you have a Mitch Hitch. The LR one is not suitable for use with a WDH. There is a thread here with a dozen or so pages on why you shouldn't - have a read first.

Cheers,

Gordon

[roamer]

Sheerluck and Mowog

Why would the recommendation not to use a WDH need to be heeded any more than.

suspension alterations to allow faster travel at off road height
long range tanks
rear wheel carrier
non genuine bull bar
at one point, aux battery isolators
Mitch hitch
different size tyres

EAS will level the car, but will not transfer weight back to front wheels.

Agree that WDH is not a substitute for poor van weight distibution,
but in an emergency all the electronics in the world will not put weight back on them steerers.

[gghaggis]

Sheerluck and Mowog

Why would the recommendation not to use a WDH need to be heeded any more than.

suspension alterations to allow faster travel at off road height
long range tanks
rear wheel carrier
non genuine bull bar
at one point, aux battery isolators
Mitch hitch
different size tyres

EAS will level the car, but will not transfer weight back to front wheels.

Agree that WDH is not a substitute for poor van weight distibution,
but in an emergency all the electronics in the world will not put weight back on them steerers.

Here we go again ........

Reasons why you can't:

1. the tow hitch won't take the load (moot if you have a Mitch Hitch)
2. Voids your warranty (moot if you don't care)
3. The car's ACTIVE system will try to work against the pivoted load. Not good.

By self-levelling, the system will transfer a % of force to the front axle anyway.

Cheers

(Please not another 12 pages on this) Gordon

[roamer]

Here we go again ........

Reasons why you can't:

1. the tow hitch won't take the load (moot if you have a Mitch Hitch)
2. Voids your warranty (moot if you don't care)
3. The car's ACTIVE system will try to work against the pivoted load. Not good.

By self-levelling, the system will transfer a % of force to the front axle anyway.

Cheers

(Please not another 12 pages on this) Gordon





Settle down Gordon :)

The question is, why obey this recommendation of "not to" and not obey the others, they all have reasons as to why they are not recommended

But they have elected to criticise someone for not taking LR advice
When I'm sure they have also ignored LR advice on other mods that suit them

Cheers Ken

[Graeme]

By self-levelling, the system will transfer a % of force to the front axle anyway.What's the mechanics of this? The levelling ensures that the front and rear suspension geometry are as they should be and the front and rear suspension have their normal bump-stop clearance and the occupants can see the road properly but I fail to see that there can be any weight transfer.

[Ghind]

Welcome, and an immensely brave first post.

It states very clearly in the handbook for both the D3 and D4 that a weight distribution device must not be used. The theory is that the onboard systems can detect trailer sway, and are able to correct it.

Thanks for the welcome Sheerluck, you are right a bit brave but oh well!

From memory, the p38 handbook says the same thing. However the p38 would be a deathtrap with my caravan without a WDH even though everything is within the ratings of the car.


Here we go again ........

Reasons why you can't:

1. the tow hitch won't take the load (moot if you have a Mitch Hitch)
2. Voids your warranty (moot if you don't care)
3. The car's ACTIVE system will try to work against the pivoted load. Not good.

By self-levelling, the system will transfer a % of force to the front axle anyway.

Cheers

(Please not another 12 pages on this) Gordon

I did a search on this forum for WDH and read lots today. There do seem to be people towing large vans with decent ball weights without WDH on a discovery 4.

By the sound of it, maybe the Discovery 4 has enough capability in its design to cope with the loss of front end grip from not having WDH.

Gordon may be right in saying they are not necessary. I also understand now that the standard tow hitch apparently fails if you use one!

Many of the examples I found when searching were pretty irrelevant. For example towing a 1.5 tonne caravan without worries. Its rated to 3.5 tonne so I'd hope so!

What I'm interested in is how well a disco 4 tows a 25+ foot body (30ft+ overall length) caravan which is almost 3.5t in weight and 300kg+ ball weight. Just how stable is it without a WDH

On of the oft quoted examples I kept finding in my searches was that the front axle weight was reduced by (i think it was) 60kg for a 140kg ball weight. This 60kg reduction was considered nothing in a 1100kg front axle weight.

I agree. Then again I've never seen any full size 4wd need WDH for only a 140kg ball weight. If you extrapolate that out however to 150kg front axle reduction for a 350kg ball weight, it becomes much more significant. The swing is even worse. With WDH you could actually move say 100kg ONTO the front axle. So your front axle grip comparison becomes 950kg without WDH to 1200kg with. This makes a massive difference to grip and stability and headroom to control sway.

Maybe there is enough headroom in the design of the d3/d4 that it doesn't matter. I would like to tow my caravan with one to find out and would do so before purchase given this WDH issue.


What's the mechanics of this? The levelling ensures that the front and rear suspension geometry are as they should be and the front and rear suspension have their normal bump-stop clearance and the occupants can see the road properly but I fail to see that there can be any weight transfer.

Graeme, you are correct. There are no weight transfer improvements from air suspension leveling. Nothing happens to magically remove weight from the rear axle and put it back on the front.

Maybe overall I could yet agree with Gordon's and certainly some of his points are valid and important (eg standard hitch failes if used with WDH). One comment that is incorrect however "By self-levelling, the system will transfer a % of force to the front axle anyway". No this is not true.

All self leveling does is let air out of the front bags and put more in the back. It makes the car level but it does not change engineering principals in any way. This can be verified with a weigh bridge and is verified in the example of a 140kg ball weight reducing front axle weight by 60kg. The reason that 140kg of ball weigh reduces front axle weight by only 60kg is that the tow bar is much closer to the back axle than the front axle is.

For example, my 20kg 5 year old daughter can sit on one end of the sea-saw and bounce me up and down on it, as long as I sit pretty close to the centre pivot point. If I sit at the end, she can't move me but if I sit close to the centre she can.

In the attached diagram you can see the front axle is about 2.3 times further from the rear axle than the tow bar is (i.e 140kg:60kg ratio)

If you google Collyn Rivers WDH you will see some useful stuff about this.

Maybe Gordon is right about the D4 being such a competent tow vehicle that you don't need a WDH. Having WDH would certainly improve stability as long as it doesn't introduce other problems.

However given some of the things I've found in search today, including comments from Hayman Reese technical staff, maybe the D4 is so good it just doesn't need it.

I still think it is a shame if it can't be used with them.

And I suspect the recommendation not to comes from Europe where it is rare to exceed 150kg ball weight.

Greg

[TerryO]

Hi Ghind,

It was me who put up the quotes from the Haymen Reece technical manager about a D3/4 not needing a WDH.

He told me they did various tests at Sandown Raceway towing a large van at various speeds and had no issues at all. Now that was done with a D3 which does not have anywhere near the same level of electronics to assist with towing as a D4.

Given that selling WDH's is a fair chunk of their business one could reasonably expect that if Haymen Reece could find a chink in the D3's towing armour then they would commercially exploit it.

As for Collyn Rivers, well at best he is a self proclaimed expert on nearly everything and is very happy to tell anyone who questions his comments that they are basically stupid idiots. It's a wonder some old grey nomad hasn't tracked this rude arrogant man down and punched him in the head or run him over with their Patrol.

I have no doubt that his ramblings are correct for Toyo's and Datsun's which obviously need WDH's, just as my D1 and D2 does, but my D3 is a delight to drive when towing our 2.5 ton van. Plenty of others on here tow 3.5 ton vans with no issues and often giggle about how good towing is with a D3/4 without a WDH.

Having said that if your shocks are stuffed then a D3/4 can become quite scary when towing, this I know from first hand experience. But as soon as the shocks were replaced it went back to being a suburb tow vehicle. I would suspect on most vehicles a WDH masks stuffed shocks.

Anyway Greg good luck with it and as others have said welcome to the forum.

[slug_burner]

here (http://www.google.com.au/url'sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDYQFjAB&url=http%3A%2F%2Fpeople.bath.ac.uk%2Fen8cjk%2FCara van.pdf&ei=4riFUdb8FIi1iQeL9IDYCA&usg=AFQjCNFASNFUid0KKL000ugBQL6Zb2gflw&bvm=bv.45960087,d.aGc) is a paper discussing towing stability.



The study showed that the most important factors that affect the lateral stability
of caravans are; speed, caravan mass, caravan yaw inertia, tow ball load, axle
position, wheel track and tyre stiffness.

Of secondary importance were caravan suspension damping, caravan roll inertia and the height of the centre of gravity, all
of which make the caravan more prone to roll over

[Glynhouse]

As the O.P. I think we have gone a little off track, I am not using a WDH at present, and according to the experts (Commercial operators that I have called on here in Sydney) they believe I have a rear end problem (don't we all ).
Will post the results after it has had some work done on it, goes in tomorrow but will be the end of the week before we get the van back on it.

My van tows perfectly behind other vehicles, we have owned it since new and it now has around 150k on it. Suspension done up fully about 15K ago, I will be disappointed if the Disco can't handle a normal van ?
Some of you seem to be saying that the van needs to be "different",

I have not weighed it this trip but is normally around the 2800kgs mark and approx 300 on the ball. The tyres in the van now have 80K on them have been rotated once have no cupping or strange wear patterns, but are getting past their use by date, so I suspect there is nothing wrong in that department, out of interest they have a maximum pressure allowance of 36psi which they are at.

DD

[slug_burner]

DD/Glynhouse,

The issue of stability is not solely down to the van or the vehicle, it is the combination of the two that determines the speed at which you will not be able to recover from an instability event/snaking. If your tow vehicle is heavy enough and has a stiff enough rear end it will not go unstable. One of the things that you require for the system to start snaking is lateral movement of the tow ball. Therefore too much flex in the tyre walls could be enough to cause that lateral movement.

There are things that can be done to the van to make up for too light or to soft a tow vehicle, a simple one in design is to make the A frame longer, not much help to an existing van I know.

According to the youtube promotional video linked here if you have trailer stability assist which is available in the later Discos, D4 yes, don't know about D3, you should be able to make up for some instability that others would not.

[TerryO]

Has anyone seen this caravan fitted stability control system from Al-ko that can now be ordered on new Jayco's or retro fitted to older vans?

About AL-KO Electronic Stability Control (ESC) (http://www.alkoesc.com.au/escfaq.html#.UYclP8saySN)

It seams to work pretty good from the video.

I'm not saying just fit it and don't worry about how your tug handles when towing, rather it looks like a great safety over ride system that keeps everything sorted when the kaka really hits the fan.

[Glynhouse]

Terry a belated thanks for the weekend accommodation !

Met a few vans with it fitted when we were in the U.K. those that had it fitted thought it was great, but when asked why they felt that way and was it obvious the answer was alway. " No but it will be if I need it ! "
Can't help you any more than that.

DD

[mowog]

I tow at the extreme end of the D4 capability my van is 3500kg in travel trim I have a 320kg ball. I have a Kaymar Rear bar and a long ranger tank all up I am at 6580kg.

I have had no issues even when I had worn rear shocks (replaced under warranty) I had no issues.

This problem with sway must come down to rig setup or driver issues. There was someone a while back with sway issues with a D4 it turns out he was over correcting when he felt motion from the van.

My van is defiantly more stable on its Control Rider (coil shock independent) than it was on Simplicity Suspension. I know many people are happy with Simplicity but until you have towed the same van with both you simply wont understand how average Simplicity is.

The van towed ok on Simplicity it however was more prone to moving around and being affected by cross winds and trucks passing.

If you have a sway issue look at the van configuration first. Then think about how you actually drive because the problem may really be between the seat and the steering wheel.