Caravan Towing Set Ups

[mrbitchi]

Just note that the Anderson WDH will only work with a rigid style ball coupling, ie your standard 50mm non articulating ball hitch.

[Ian H]

Just note that the Anderson WDH will only work with a rigid style ball coupling, ie your standard 50mm non articulating ball hitch.

They come with their own tongue and ball.

[old Jack]

https://rvdaily.com.au/weight-distribution-hitches-use/

OJ.

[PajNX16]

I can follow how the bar type WDH work but the Andersen has me wondering, as I have a DO35 set up do to rear door issue and I may not be able to use them .
Van handles very well on smooth roads but when roads are undulating you get the bounces around a bit, may be all vans do to some extent?
I think that if the rear springs don't compress in the first place, as much as they do now it might help a bit. ie a bit heavier spring loading?
thanks to all

[johnhgh]

I found the WDH made a huge difference to the porpoising on mine, the heavy springs and air bags supported the rear but I still needed the WDH to stop the bouncing.

[terryfirma]

I also have a DO35 hitch and find its great.
When connected there is sufficient clearance to enable the rear door to be opened without the door hitting the hitch.
With Hayman Reese WDH attached the car/caravan sits level. This set up definitely stop sway and pitch and with a 21ft van it is a pleasure to tow.

Cheers
Terry

[Dicko1]

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

50 psi is way too much. Get bilsteins and lovells springs. I tow close to 2 tonne at times and I only put about 15-20psi in airbags at the most. Handles like a dream and sits comfortably on 100kph. Stock suspension with 2 tonne is just dangerous in my opinion. Most highways in Oz are shite. Undulations soon see the standard suspension and heavy weight being a bugger to handle. 180kg on tow ball should be fine. Obviously your suspension is letting you down and putting higher pressures in your airbags is only masking the problem. Before an accident occurs...get your suspension sorted.

[PajNX16]

Hi All,
just did some measurements, with van straight and level the DO35 base is 50mm higher than the Paj
tow ball and that is with the hitch turned up to get highest height.
Then with the 180kg tow ball weight it drops a further 30mm. If spare was not there could use adjustable level hitch.
Part of the problem is the van hitch should have been set in the A frame which would have helped.
Looked into getting it lowered but would lose 8" of the A frame.
As with some of the set ups you guys a using a 2" lift would help.
I will have a talk with Kings regarding their Progressive heavier springs.
Thanks again for your help.

[nj swb]

You've posted that your rear drops 30mm and front rises 25mm but we don't know the starting heights - so we don't know if your unladen Pajero is still at original factory height, or if it has sagged.

Please measure the vertical distance from the centre of each wheel to the edge of the guard, on all four wheels, and post the results.

[PajNX16]

NJ SWB,
as requested, Tyres around 38psi...
Front Driver Side: 510mm Passenger Side 510mm
Rear Driver Side: 520mm Passenger Side 520 +- Airbag around 5-10psi
Got the Paj new so all original..
cheers

[old Jack]

RVCS data is 504mm front and 533mm rear for a stock new MY16 Pajero.

If you caravan is a dual axle then ideally you want a level drawbar even if it has independent coil or load sharing leaf suspension. If it has non loading leaf suspension then keeping the drawbar level should be a priority.
When the drawbar is level what is the height of the underside of the coupling?
50mm ball coupling or something else?
What is the height of your towbar when the caravan is not hitched, measure from ground to centre of the ball or base of coupling?

OJ.

[PajNX16]

OJ,
Van straight & level, flat base of the DO35 hitch is 535mm above ground level.
Paj tow tongue top is 505mm AGL, as I said this is with the tongue inverted so about 25mm difference.

[nj swb]

;

OJ,
Van straight & level, flat base of the DO35 hitch is 535mm above ground level.
Paj tow tongue top is 505mm AGL, as I said this is with the tongue inverted so about 25mm difference.

So, your rear is sitting about 10mm below factory spec, and your front maybe 5mm higher. Some of this difference may be simple measurement tolerance, but having a tow bar mounted out behind the rear axle will be contributing too. I don't think your factory suspension has sagged excessively.

It sounds like you need your rear end to be about 25mm higher than its current unladen height, with the van on the back. Airbags like you have won't do that.

Presuming you buy some replacement springs with a higher rate, the rear shouldn't drop as much as it does now. So I think you should be targetting some aftermarket springs that will provide 40mm lift above standard (50mm above your current) unladen ride height, and droop about 25mm with the van on.

My guess is a HD spring rather than any of the EHDs, but OJ is your man for this! I would lean towards a taller spring with a lower spring rate, so you can still have some comfort without the van on the back, and keep the airbags for fine tuning if necessary.

[PajNX16]

NJ SWB,
yes measurements could be a bit out but, seems like as others have done next size/load springs will make it better, not sure of higher springs though.
thanks
OJ, remeasured the set up , the pin of the DO35 sits in by about 5mm so that will add 5mm to the height (30mm higher)

[old Jack]

OJ,
Van straight & level, flat base of the DO35 hitch is 535mm above ground level.
Paj tow tongue top is 505mm AGL, as I said this is with the tongue inverted so about 25mm difference.

All good info.
In an ideal world I would be looking at the top of the towbar tongue being about 30mm higher than the base of the DO35 coupling.
This is 80mm in total, this means a rear suspension ride height of 600-605mm, this is way too much for a suspension lift on Gen 4, max legal and sensible lift is the 570-575mm.

If you plan to do a lot of towing with this caravan then a inset hitch on the drawbar would be a great place to start, even if it means losing 200mm of drawbar length.m

Contacting Kings, they will only be able to tell you the free height and the spring rates of the coils they make. I already have all these for King, Lovell, Old Man Emu, Dobinson and factory. But this data does not give you a clear picture of what happens when the coils are fitted. I have a 1200 cell Excel calculator that uses the above data for each coil, it compensates for unsprung weight and suspension geometry so it gives an indication of axle loads for a given ride height and operating spring rates at these ride heights. It is not super accurate as the manufacturers specification that can vary between 5% and 7%, this may not sound a lot but a 10mm height change in spring length will result in about 18mm change in ride height.

Also you need to take into consideration the effect of the weight transfer from the front axle to the rear axle when looking at coil selection. Ideally you do not want to load your WDH up more than what is required to transfer the transfered weight back on to the front axle.

Have you actually done a physical towball download weight of your caravan?

OJ.