Unless the vehicle manufacturer prohibits it, you would be a fool not to use a WDH when towing a caravan, especially on a D2 with it's stupidly short wheelbase and long rear overhang which increases the effect of any weight on the towball.
It doesn't matter if the car and van suspension is perfectly set up, dropping a van on the towball WILL increase weight on the rear axle and reduce it at the front where most of the braking and all of the steering is done. Forget Polyairs and the like; they may keep the vehicle level and create the illusion that all is well but they do nothing for the weight transfer.
The question is - how much weight can be taken off the front axle without it adversely affecting braking and steering? A heavy 4WD won't be affected as much as a passenger car, but every towing vehicle will be affected to some degree.
Use a WDH and the question doesn't arise. The ball weight is still there but the EFFECT of the weight is spread more evenly over three axles instead of one.
As I said, it is easy to see who has tested correctly setup WDH and who hasn't. The air bags just make it sit level. still a huge weight reduction off the steering wheels
Agree - 12 years with a rig that handles significantly better than without the WDH - I ain't going back - and I've had air suspension for all that time and wouldn't go back to coils... the vehicle will improve with a CORRECTLY setup system - some more than others.
L322 3.6TDv8 Lux
There is no questioning the effectiveness of a correctly adjusted WDH. Unfortunately they restrict turning circle and draw bar articulation making them unsuitable in some applications, particularly off road. With caravans off road means off the bitumen.
This is where Polyairs come into play as they restore ride height and rear spring travel. Steering and suspension articulation is also restored and the tendency to bottom out the rear suspension is lessened. Polyairs do not restrict turning circle or draw bar articulation.
It's pretty simple really, for heavy towing on the bitumen use a WDH, for off road use Polyairs
This is a horses for courses exercise, use which ever suits your type of travelling.
Deano
If you are going to go into a situation where articulation (up and down) is needed and you leave a WDH system setup you need to have your head read, something will break, i have seen the end result from driving on a bush track with a WDH fitted, they ended up with no tow bar left to tow and someone else had to tow there van for them
was watching a big dual axle van and landcruiser with wdh go through town center the other day, we have a raised intersection for speed and pedestrian safety i guess, and as the van went up and then back down you could see and hear the stress on everything and it was a cringe moment for me watching, being mechanically trained and the son of an engineer. i cant understand why a dual axle would ever need a wdh. just doesnt add for me.
I have towed a lot with my 02 D2 coiler...mainly a 2 tonn dual axle boat trailer/boat - Seafarer Vagabond. It tows very well (with quite a lot of ball weight) including loaded up for interstate runs/camping with the boat. It does drop the back of the truck though with standard springs by 3.5cm (and more if the truck is loaded). So today I have fitted coil rite by Firestone and I am confident that it will tow even better with them. I will report back on it though.
In the meantime the air bags with 8psi in them make the rider better. The truck has 31 inch LT's, Raw Dampener for the steering and Dobinson GT shocks all round (all that gear is pretty new) and the coil rites make it even better...funnily enough it rides now VERY much like my brother in laws 95 P38A Rangie with air suspension (the bags reduce pitching nicely and give it a very sure footed feel).
Cheers
I am keen to hear how you go
In reading all the posts here All I will say is that my understanding is that airbags like polyairs are to absorb up and down forces of the weight
This is the most debated subject within the caravan industry- I have never seen it end with one side or the other saying you were right- This is one of the most nicest debates, they usually end with arguments not debates![]()
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