Thread: In Sydney need advice instability when towing

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

Originally Posted by Graeme

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.

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.

Originally Posted by 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.

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

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.

Originally Posted by 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.

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

Originally Posted by gghaggis

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

Originally Posted by gghaggis

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.

Originally Posted by sheerluck

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.

Originally Posted by gghaggis

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.

Originally Posted by Graeme

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