LANDCRUISER TURBO AUTO TOWING

If u use a WDH u wouldnt have to adjust your lights all the time as the car would sit more or less the same regardless.
Polyairs dont level the car when you have a van on the back they just poke the rear up a bit higher.
Its the WDH that levels a car with a van on it as the weight actually pivots the car at the rear axle point and the WDH then straightens it out by pivoting the weight forward.

Sorry Graham I can't agree with you there. My travelling buddy has polyairs and his rig sits level with and without the camper. He simply adjusts the pressure to suit. He never adjsusts his lights, and I'm always adjusting mine.

You say --- "Polyairs dont level the car when you have a van on the back they just poke the rear up a bit higher".

If polyairs don't level the car I'm a monkeys uncle!

Sorry about that but its a matter of where the weight is and where the pivot point is
If you apply weight to the towbar it pushes the bar down and pivots the car on the rear springs so the front comes up. Doesnt matter how far you pump the Polyairs up the laws of physics or whatever still applies. I have polyairs and the front still comes up regardless of their pressure until I hook up the WDH.
There is a good article on towing both here and on the Hayman Reece site which explains it all much better than I can.
Try measuring up to your mudguard roll before and after hooking up and see the difference. Unless you have a very light trailer there will be one.
Say hullo to your nephews for me. LOL
Cheers

I have to agree with Muzz on this one. Our Prado was sagging a bit in the rear with the camper on which of course made the front sit higher. Now I have Polyair bags installed it doesn't sag and maintains a fairly level stance, therefore the front isn't lifting up.
Perhaps Graham the Polyairs are too light for your load. I think they are rated at 300-400kgs, not sure, and I use them in conjunction with medium duty springs. If I had something heavier than my camper trailer I would have to go for either heavy duty springs or heavy duty air bags (the black ones). Looking at the size of your van in your rig pic, the Polyairs with their light rating might be struggling?

Cheers,

Mark.

Polyairs or any springs only hold up the load directly above them and help a bit with towball loads. Towing a van and putting weight on a towbar causes leverage. It pushes the towbar down and pivots the car on its rear suspension point. pumping up springs or even putting a jack under them does not alter the leverage it only lifts the height of it.

Think of a seesaw u put weight on one end the other end rises So u put polyairs under the centre Does the high end go down NO cos it cant.

Thats what a WDH is for It redistributes the weight by pulling up on the joint between the van and the car therefore levelling the rig out. Wont matter if you have helpers on your springs or not you cant over come the weight on the towbar cos its always there. If you have a 315kg ball weight its always that regardless of how much you pump up airbags or pull up on your WDH.
You can only straighten the line thru the rig to take some of the pressure off the rear and put it forward on the car and some rearward on the van. Put a scale under the towball after doing that you will still have 315kg
My rig sits level whether or not I pump up the airbags simply by adjusting the number of links on the WDH. I only put the bags in so it would help the springs when the car is fully loaded

Incidentally the pic of my rig was taken BEFORE I put the bags in and its sitting perfectly level. It may look like the van is down at the back but it isnt square with the car so its an illusion. I had just pulled around in a big circle to park it out of the way at the Lennox head car park and dint get it quite straight.

Read this
http://www.go.id.au/2007/05/01/load-levelling-devices-the-real-story/ and this

http://www.exploroz.com/Vehicle/Caravans/ChoosingandSettingUpaTowVehicle.aspx
One cannot defeat physics unfortunately
Cheers

Graham, I'm not an engineer, but I gotta say your argument has more holes than a swiss cheese. If a seesaw goes up one side, the other goes down ---- WHAT?

I dunno whether to laugh or cry!

Nowhere did I say you are changing the ball weight by using polyair bags, you are simply lifting it, yes, which you aknowledge yourself. When you lift the rear of the car to compensate for the wieght of the load the car levels out again and the proof is in the fact that the headlights will shine up the road as they should, not up in the trees as they do when the bum of the vehicle looks like it's dragging on the ground.

I undserstand why heavy duty load levellers are needed when towing big vans or trailers, and airbags do not hold as much weight, but to say that airbags do not level out a vehicle is simply untrue.

Whatever

Hi all,

I agree with Graham but I don't think he has put his case clearly.

When you put weight on the towball the back goes down (extra weight) and the front of the car goes up due to the see-saw effect.
Polyairs can level the car by raising the back sufficiently thus resulting in correctly aimed headlights, but they do not solve the problem of less weight(adhesion) on the front wheels.
If towing a large trailer/van it is necessary to use load leveling bars in order to put back some weight onto the front wheels to minimise the likelyhood of swaying.

Hope that helps

Peter
HZJ 105