Caravan Towing Set Ups

[PajNX16]

Hi All,
I am not overly happy with the set up for caravan towing on my Pajero NX.
While I have done over 10,000 km's which have been ok I think I might be able to improve things. As some roads are bad I am trying to stop a bit of the bouncing.
Van has ball weight of 180kg, and when hooked up drops about 30mm at back and lifts 25mm at the front. I have airbag man air bags on to lift the back up. I don't carry much extra weight in back and have rear seats removed. Options I have thought of:
1. Fit next load capacity rear springs
2. Heavier duty shocks
3. WDH - may be 180kg 2 bar weight Distribution Hitch
I don't really like depending on the air bags for the rear lift.
thanks for any advice
cheers Garry

[old Jack]

Hi Gary,


What pressure are you running in the airbags?


OJ.

[PajNX16]

Hi Old Jack,
Running 50 psi to get things level, had to go the Kevlar sleeves.

[Ian H]

As long as it's a normal road van and not going off road (creek crossings etc) then a WDH would be my answer. It will move weight off the rear axle and on to the front. It shifted 160kg off my back axle, of which 100kg went to the front axle and 60kg back to the van.

Are you pumping up the air bags before hitching up ? They do the job of increasing spring rating which stops excessive sagging but they don't move weight away from the rear axle like a WDH will do.

I did a presentation for our 4WD club and the video is online

https://www.youtube.com/watch?v=uOX3vTmZOgk

It talks about ball weights and what all the acronyms mean but the actual weigh bridge test starts at the 6min mark and shows what the WDH can do to distribute weight.

[deekay]

I have an NW Pajero that I have set up with heavy duty rear springs & air bags .I run about 20psi in the air bags when towing and 5 psi when not towing. There is virtually no downward movement when I hitch up the caravan & I don't need any WDH. The van tows a lot better with out the WDH setup.

[Ian H]

The van tows a lot better with out the WDH setup.

The only way it can tow better (whatever that means) without a WDH is if you've got the hitch set up incorrectly. There's no way adding an extra 200kg (approx) to the back of the vehicle and removing weight from the front axles can make it tow better.

[PajNX16]

Thanks for the info so far,
Ian can you advise what size WDH you use, I don't like the idea of putting an extra 28kg+ WDH set up on the tow ball. I was thinking of using a 180kg 2bar WHD which would be less weight.

[Ian H]

I use the Eazlift 275kg set, which is the middle range. The van is only 16' and has an ATM of 2200kg. Ball weight about 180-200. The smaller one isn't enough if you have a decent size van and ther large one is not necessary.

Don't stress about adding weight to the rear by adding a hitch. I went through the same exercise but when hooked up correctly the van rides level and the weight it removes from the rear is 4 times what the hitch itself weighs. The middle Hayman Reece model would do the same job and now there's the new Anderson type which is probably what I'd get if I was buying again, although they are a lot more expensive.

We've had a guy just join our club who has spent many years working for Hardings, one of the largest and most established caravan service and repair companies in Victoria with a reputation for good advice and quality work. They recommend a WDH for every caravan with the exception of off road when you are going up and down over creeks or large undulations. In those extreme cases, the extra strain on the hitch can, and has, snapped a hitch clean off the car.

But for highway and normal dirt roads, they are a must in my view. The video I posted shows that without the hitch, my rear axle is over the MM specs for maximum weight but with it on, the car becomes legal again, even though I've added the weight of the hitch itself.

[Morten]

I got the NX,standard suspension, and a van at 1850kg ringing wet, 180 on the ball, without the WDH, its not bad, but the car bum goes down and I'm on my game steering,braking,etc etc.....with the WDH, its way better, a lot more stable so to speak...and the whole setup just sits on the road....the one thing I've found, with the Paj and my Ranger towing the van, is tyre pressures...38psi on the steer in both, 40 on the rear and van is where my show is best....I'm going to do the whole weighbridge thing with the Paj and van soon, just to get the idea, but we do travel light all the time...

[PajNX16]

thanks Ian,
Van is a road dual axel with the 180kg ball weight, handles very well with the set up I have but just trying to lesson the porpoising when going over the bad undulating roads.
Would the WDH act as another spring and push the back up when rebounding or would it lessen the initial compression downward

[old Jack]

Hi Old Jack,
Running 50 psi to get things level, had to go the Kevlar sleeves.

50psi that is really high and high risky if you have an airbag problem.

Look at you weight distribution when loading. What weight can you move towards the axles of the trailer? Work on weights both forward and rearwards of the axles, this will reduce your ball load but also improve dynamic stability. Adding weight to the rear of the trailer will reduce towball downloads but decrease dynamic stability and you risk having a very unstable trailer that is likely to sway out of control!

Standard height HD King rear coils are progressive rate and are comfortable when the vehicle is not loaded and firm up when loaded so these will take the load of the airbags, $200-$250 a pair and about the same to fit them.

I would suggest using a Anderson WDH as theses are better for rough/undulating roads and when correctly setup retuen the front ride height to normal and transfer weight back to the trailer wheels without overloading the towbar, drawbar or coupling. The also have an anti sway feature.

Best to do all 3 of the above actions to get a safe and stable towing setup.


OJ.

[Ian H]

thanks Ian,
Van is a road dual axel with the 180kg ball weight, handles very well with the set up I have but just trying to lesson the porpoising when going over the bad undulating roads.
Would the WDH act as another spring and push the back up when rebounding or would it lessen the initial compression downward

Yes it does act that way which is why they can break a hitch if you are on extreme undulations (whoopsies for example) but it's fine on normal undulations.

[PajNX16]

OJ,
Can't do much about moving the load in the van, with MM max ball weight i would have thought it could handle the 180kg ok.
Yes will check out the King springs and may be, the medium WDHs.
thanks to all for your input.

[old Jack]

OJ,
Can't do much about moving the load in the van, with MM max ball weight i would have thought it could handle the 180kg ok.
Yes will check out the King springs and may be, the medium WDHs.
thanks to all for your input.

Can you pack it differently?

Even relocation of spare wheel and jerry cans off the rear of the caravan will improve stability.
How much unnecessary heay stuff is in the front locker on the drawbar?

180Kg of ball load transfers approximately 70kg of weight from the front axle to the rear axle so that is an extra 250kg load on the rear axle.

Anderson WDH is really the way to go from my research and worth the extra cost.

Factory rear coils are 350mm free length and have a spring rate of 562-740 lbs/inch.
King KCRS-35 are 335mm in free length but have a spring rate of 660 -1000lbs/inch, this is 18% higher spring rate at the start of the compression and 35% at full compression so at the factory ride height of 533mm these coils will be about 25% firmer than factory coils.

Minimum legal ride height of rear suspension when loaded is 488mm, measured from centre of wheel hub to underside of wheel arch when measured in a vertical line.


OJ.

[PajNX16]

OJ,
Not much in front boot mainly shade walls, jack and hoses etc, I travel pretty light and have removed the third row seats for the wife's dog (grrrr!) which weighs in at 40kg.
thanks for the info on the kings springs.
I struggle a bit to see how the Andersen WDH works to put much of a load back onto the front wheels but suppose they must work?
cheers