Weight distribution hitch versus poly air bags

Waz and Vick · Newbie

Weight distribution hitch versus poly air bags

Rod Mac · Veteran Member

For me with a Pajero with standard springs and towing a tandem pop top, I went with Poly Air Bags.(60 HP MODEL)
The van goes 2150kg loaded and when being towed goes 1950kg after 200kg goes on the ball (weighbridge weights)
For a previous Pajero I fitted 400kg springs all round and still had rear end sag and front end lift, plus they added 40mm lift, (wife not happy)
Also when travelling I have 70kg rear draw system plus 2 fridges with food and drink, so a fair bit on the rear.
The Pajero has coil springs, so air bags are a natural fit, for me anyway, I assume the Lux has leaf springs in rear.
Very happy with the air bags, I run 20psi empty and 50psi towing, much better than the stronger springs, (wife happy, Pajero at Standard height)
Result is minimal sagging and virtually no ducking or diving, what I call "porpoising" on undulating roads which I still got a bit of with the stronger springs.
Some will swear by the WDH, others won't, WDH don't appear to offer any extra safety, they are not anti sway devices. (look up Claytons Towing for their assessment)
My fundamental reasoning against using WDH is, if they are needed then the weight distribution is wrong.
That's my 2 cents worth.

Comfy chair, a drink and popcorn time....

rockylizard · Guru

Gday...

This demonstration is worthwhile, Waz.

Take the time to watch all the way through for the final comparison.

https://www.youtube.com/watch?v=XBZu39pQ8Gg

It might be a good move to actually determine the axle weights of the HiLux - you may have it a tad heavy even before you add the towball weight of the van.

That might be what is creating the problem - combined with the 'softer' suspension they provide with the SR5 for 'better ride'.

Cheers - John

Dougwe · Chief one feather

Interesting video Rocky. A bit confusing with lbs etc but went back my childhood and started to get the drift.

When I first got my aluminium teepee I had a similar problem where the back of the Collie went down and lights at front up. I had an extra leaf fitted to both rear springs that raised the back up 50mm. When I hooked up the aluminium teepee it dropped 50mm levelling everything up nicely. I have had no problem now for 4.5 years. I still get a comfy ride without the weight on the back. I do have weight in the back of the Collie all the time though as I am full time on the road.

I don't use a WDH or air bags. I am on the understanding that if airbags are fitted to the twin cab Utes you risk braking it's back.

All seems to work OK for me so I'm a happy camper, well traveller.

Whenarewethere · Guru

I never towed but had rear air shocks on a Peugeot 504. When fully loaded I pumped up the car with onboard pump. I felt it handled a bit better with the rear at the right height. Probably overloaded the car a bit at times but the air shocks were very handy. Also good to get about 5cm extra ground clearance at times even though it was the rear, it had an overall benifit.

Peter_n_Margaret · Guru

Weight distribution hitches and air bags do quite different jobs. It is not a question of one or the other.
WDHs transfer weight from the rear axle to the front axle to maintain steering integrity. Air bags can not transfer weight.
Cheers,
Peter

TheHeaths · Guru

Firstly, see what P n M say. As he says, they do 2 different things.

Secondly, what does Toyota recommend with respect to the use of a WDH with the Hilux.

Be guided by them.

-- Edited by TheHeaths on Monday 22nd of April 2019 08:09:41 PM

yobarr · Guru

Peter_n_Margaret wrote:
Weight distribution hitches and air bags do quite different jobs. It is not a question of one or the other.
WDHs transfer weight from the rear axle to the front axle to maintain steering integrity. Air bags can not transfer weight.
Cheers,
Peter

Nice one Peter....I was beginning to wonder if anybody would ever point that out.And as Dougwe pointed out,airbags should not be used with leaf springs because they point-load.If you Google something like Bent Twin-cab chassis you will find pages of photos,stories and explanations.Cheers

rockylizard · Guru

yobarr wrote:
Peter_n_Margaret wrote:
Weight distribution hitches and air bags do quite different jobs. It is not a question of one or the other.
WDHs transfer weight from the rear axle to the front axle to maintain steering integrity. Air bags can not transfer weight.
Cheers,
Peter
Nice one Peter....I was beginning to wonder if anybody would ever point that out.And as Dougwe pointed out,airbags should not be used with leaf springs because they point-load.If you Google something like Bent Twin-cab chassis you will find pages of photos,stories and explanations.Cheers

Gday...

I guess then you view the link I provided for advice as as waste of time then. confuse

Dunno know why I bother sometimes. cry

..... the OP said "poly air bags (which I had successfully for 13 years on the old Hilux" so I guess they are extremely lucky or have loaded and used their previous HiLux wisely. hmm

Not everyone has 'broken the back' of their ute with airbags.

Cheers - John

landy · Guru

I was also waiting Peter and Margarets answer. Although both appear to do the same they are birds of a completely different feather. To my mind especially on a dual cab distributing some of the weight to the wheels that steer has got to be the better option. But bearing in mind that it will put other forces into play you should always get advice from your local dealer before doing either.

Aus-Kiwi · Guru

Yes dont fit anything . Dont strengthen a chassis even though you see a few bent . Seems easy to me to add box section around chassis to spread the weight of airbags . Seems elementary to me !! Get a LR / MR licence and use a TRUCK !! Sheesh Weights,load balance and driving like an idiot . Then blame the suspension ?? Trouble with most vehicles ? They are softly sprung to feel good out of the showroom ..

Warren-Pat_01 · Guru

Waz and Vick,

Firstly welcome to an informative & often very helpful forum on all manner of subjects. Take your time in perusing all segments of it.

This issue was a hot potato a few months ago - using the Search button can be helpful.

Secondly, you need to know where you will be travelling. I chose to fit airbags but I chose to disobey the manufacturers' (AirbagMan) instructions because - a) I didn't want to bend my chassis/break spring supports & b) I wanted some suspension movement instead of having a suspension that felt like blocks of wood in it. Although my bags can go to 65psi, the most I add is 27psi. And I drop the pressure back to 5-8psi if the van is off the back for any long period.

If you are travelling mostly on firm/bitumen roads, take the WDH (if the manufacturer of the car allows it). If you are travelling on dirt or especially up hill & down dale as in the Tibooburra area or northern parts of the Strzelecki Track, take the airbags BUT watch your pressures. Any signs of trouble, ease the pressure/speed.

I'll probably get shot for my views but this is what works best for me. You have to choose what is best for you BUT look at the arguments both for & against!

The Belmont Bear · Guru

On the previous Pajero Sport pulling 2.7T I used both a WDH and fitted airbags. The WDH levelled the load and transferred some of the weight to the front axle while the air bags inflated to only 15PSI took out that "porpoising" effect. The advantage of the airbags over fitting heavier suspension components was that I could drop the pressure back to 5 PSI when not towing and get that nice comfortable ride around town. Having said that the Sport had rear coil suspension rather than being leaf sprung like most of the twin cab utes so point loading was not as big an issue. WAZ as I see it the WDH and the airbags do different things so there is no reason why you can't use them in conjunction with each other.

The reason I still use a WDH with my current vehicle is not as was suggested in a previous post that my weight distribution is all wrong its because the manufacturer tells me that I have to when towing over a certain weight. I tried the Jeep GC without the WDH fitted just to see the difference and although it towed OK the rig just didn't feel to be as stable or as well balanced - but then thats only my opinion.

Cheers
BB

Radar · Guru

Hi Waz

Firstly we have a crew cab ute with air bags (8 psi empty) (18 loaded max) now for 5 years, 110 000 kilometres (no bent chassis) about 40 000 kilometres ago we put the ute in and spent approximately $2000 on the suspension at a Brisbane based suspension shop. We tow 2.7 tonne caravan, 270 kg on the tow hitch, no other aids.

The car when touring is a total pleasure, we do run 40 psi in the rear tyres when towing then drop them to 34 psi for every day use, we have just this week covering some 400 kilomtres of dirt road touring around Tenterfield area, very enjoyable. We have about 180 kilograms in the back of the ute including the canopy.

Looking at what you are carrying in your ute tells me you are really over extending the carrying capacity of ute, all that weight is behind the rear axle, not good.

If I had my chance again the car would of went straight to suspension shop from the show room as the orignal suspension was not suitable for towing for any lenght of time

-- Edited by Radar on Tuesday 23rd of April 2019 01:54:37 PM

mezza56 · Senior Member

I have a 200 series with the lovells upgraded hd springs and shockers , i still use the wdh as the towball weight of 280 kg lightens my steering even with the upgraded suspension . As Peter says the suspension and the wdh do two entirely diff things . Simple put ur van on and go to a weigh bridge , weigh ur front axle with van on and then off . You will see the difference . If ur vehicle steering is feeling compromised towing the van use a wdh . Or buy an F truck

Rod Mac · Veteran Member

Hi Radar, I think maybe you should address your reply to Waz and Vick, the original post, I don't have a ute or leaf springs and am well under my GVM and GCM.

I get what you are talking about for a ute, but it does not apply to me in my situation, thanks anyway.

Also for those that have viewed the American WDH demo with the empty car trailer, I cannot for the life of me see why you would place that heavy load at the front of the trailer, just for the demo ??, then why not place the load at the rear of the trailer for comparative purposes.

That load should be placed above the axles, and then see what difference is made.

There are better videos demonstrating in model form what happens when loads are placed incorrectly, leaving out Air bags or WDH discussion.

Rod Mac

Radar · Guru

Rod Mac wrote:
Hi Radar, I think maybe you should address your reply to Waz and Vick, the original post, I don't have a ute or leaf springs and am well under my GVM and GCM.
I get what you are talking about for a ute, but it does not apply to me in my situation, thanks anyway.
Also for those that have viewed the American WDH demo with the empty car trailer, I cannot for the life of me see why you would place that heavy load at the front of the trailer, just for the demo ??, then why not place the load at the rear of the trailer for comparative purposes.
That load should be placed above the axles, and then see what difference is made.
There are better videos demonstrating in model form what happens when loads are placed incorrectly, leaving out Air bags or WDH discussion.
Rod Mac

Thank you Rod my finger was working to fast.

Wasley · Member

Hi Waz

My way of thinking they are both bad as the airbags carry the weight on the weak point of the chassis and the WDH has a bad habit of shifting the weight to both the caravan axle/axles and the front wheels which can cause 2 problems (1) is possibly overloading caravan axle/axles and or overloading front vehicle axle (2) and more importantly because it transfers the weight to another point if you get into a sway or emergency braking situation the caravan can push the tow vehicle into a jackknife situation if that happens you are a passenger. For my way of thinking put some stronger springs in but at 45mm drop I think you are over stressing.