Correct amount of air in air bags

Jackie · Veteran Member

Correct amount of air in air bags

patrol03 · Senior Member

I would think that if you have the appropriate WDH for your combination and it is fitted and adjusted correctly, then you should not need air bags to keep your rig level.

Jackie · Veteran Member

Appricatedscated your comments patrol03' however if you are caring some weight in the back of the vehicle then I believe the air bags will help level the vehicle before you hook up the van, would you not agree.

Delta18 · Guru

Depending on your vehicle a better alternative may be to fit heavier springs to carry your extra weight. Airbags are a bandaid solution to worn equipment IMHO.

Having said that, my understanding is that the bags should be inflated to recommended pressure which should be in the bag literature before loading the vehicle.

blaze · Guru

all the bags I have had over the years have been min of 5lb and max of 90lb, so I would put normal load and inflate to level somewhere between those pressures. Now fit van and adjust the wdh to suit
cheers
blaze

Peter_n_Margaret · Guru

If you need air bags, the vehicle is probably overloaded.
Better to fix the problem than apply a bandaid.

Cheers,
Peter

Dav4Cris · Senior Member

I have never used airbags in a vehicle as I have seen what happens if over inflated, fractured chassis, bent and broken, spent 25 years in the Motor Vehicle Repair trade. I have talked to lots of people and they use between 15 to 25 psi no more, if vehicle is not level then it needs heavier rear springs.

Baz421 · Guru

We have Firestone airbags on 79 series LC ute. They improve stability considerably with very little pressure and help smooth out the bumps.

We use them at between 5-8 PSI normally (sometimes 10PSI) and each 1 PSI (if I recall correctly - as I can't find the reference) provides 60lb (about 28kg) of lift/support.

So you can see this is in the lowest recommended pressure range of 10-90PSI.

We have used them for 6 years now and no problem.

I have personally seen dual cabs with Polyair bags pumped up to 90PSI - accident just waiting to happen and several pics have been shown on this and other forums.

What I am saying is you need to know why you are looking to airbags and what makes them your choice over other options ie new or reset springs to match the load.

I advise against using them as vehicle levellers as that is not their purpose.

Do some research and make an informed decision.

I hope this info helps you to do that.

Aus-Kiwi · Guru

Don't be too concerned with ride height to a point..

The trouble with upgrading springs is harsher ride..

I have them on the front of my Workhorse chassis Winnebago as std..

They fit inside up graded springs.. In this case on 50 Lb..

I have recently fitted 9" bags to the rear leaf springs which rode hard.. I tried lowering tyre pressures etc..

The tyres are quality new Michelins so its not them.. So far I have 15Lb n them and amassed at the smoothness they have made..

I find JUST setting the bag so the leaf help springs are just on the chassis works best..

The issue is when dumb and dumber think 20LB works good so 100 LB would be GREAT .. welcome to the Darwin award..

Depending who does it and kit ? The chassis bracket needs to be well designed ..

Often removing bump stop fitting bracket which spreads load ...
Above is not your specs..
Being an R51 with IRS coil spring, Separate sub frame....I would start at 10Lb and go from there..

-- Edited by Aus-Kiwi on Thursday 10th of December 2015 02:27:10 AM

-- Edited by Aus-Kiwi on Thursday 10th of December 2015 02:29:43 AM

jonathan · Veteran Member

.. just FYI

Some time ago I had Pedders fit Firestone airbags to my Dmax. Since then, and with no more than 4-6 psi inserted, the tug and van have been a pure delight to drive.

Soon I hope to be somewhat more "static" in the far north-west of NSW where the primary demands on my Tug will change from towing a van to mainly travelling about in the bush and scrubby areas (van-free) to enjoy some of the remote outback fishing and adventure locations ..

Next week I will be having an old-man-emu kit fitted and suitably adjusted for my purposes without presenting an "overkill" of my intentions and will still retain the airbags in a manner that will allow me to engage/disengage them as required. This latest installation is being carried out by a professional service and by well credentialed fitters.

I'm quite happy to make these decisions after first placing it in the hands of the appropriate Professional resources ..

-- Edited by jonathan on Thursday 10th of December 2015 06:54:32 AM

Jackie · Veteran Member

Many thanks for all the feedback, the Parthfinder is fairly soft in the rear end and the air bags have helped over the past 50,000km of towing, have been running 25 to 30 lb in them and kinda does the trick, we will be travelling full time next year so may look at putting heavier springs and gas shocks on the rear as a better fix.

Thanks all

Jackie

Brooksy48 · Veteran Member

Hi Jackie
When I bought the Pathy back in 08 and put the van on the back the weight of the van dropped the rear of the Pathy significantly. I was unable to use a WDH due to the offroad hitch and also our frequent off road travel. I had some heavy duty springs replace the original springs, replaced the shocks with OME shocks and had Firestone air bags installed. Now the car and van were level and the ride was excellent.

Aus-Kiwi · Guru

Yep new springs and quality shocks improve ride big time.. Towing shows up any degrading of parts big time..
Keep in mind these are coil springs not leaf..

Dreamweaver · Veteran Member

Had Polyair bags put in the rear coil springs of my 2015 NX Pajero. They have improved the level of ride especially when cornering with less roll which is normally found in coil spring suspension. Recommended psi of between 5 and 30. Normally inflate to between 5 and 10psi when no load on rear suspension. Pump them up to around 25psi then put the load on and let enough air out to level the vehicle. The WDH is designed to distribute the weight across the suspension of the vehicle and the air bags assist in achieving that aim. I would say they work best on new springs as they are not trying to compensate for tired ones. Certainly in the Pajero I see them as a real asset in helping firm up the rear suspension.

OutbackMK · Senior Member

I have a Landcruiser LC76 I fitted 2"lift with +300kg rear leaf springs (bit heavy round town) and firestone airbags.
I fitted them as I was getting a few high beam flashes when traveling and realised that when the truck was loaded headlights were a little high, rather than readjust headlights it was easier to put about 10-12psi in bags to get me level again (I usually run about 7psi unloaded so the bags keep their shape)
I don't use WDH's as the truck is able to take my ball weight with a lot to spare and I travel a fair bit on dirt and it would be a pain to keep removing them.
I have never used a WDH hitch but am let to believe that they should be removed off-road, is this the general consensus?

Radar · Guru

Yes, I use air bags in my Navara twin cab ute, very happy with the result.

Twin cabs of late from all manufacturers are very soft in the rear suspension, my first reaction was to go and fit stronger springs but when the vehicle was with out the caravan would of made it harsh to ride in so by fitting air bags filled to about 14 psi the set up seems ideal with the caravan.

Then adding load leveling bars has made it all work for me.

When I am running around empty I have about 8 psi. In them to help keep the bags shape, I did try totally empty of air but the bags them self still held the car off the springs and from practice I feel sure you are better to run some air in them, a better shock quality shock absorber would be a welcome addition as it has this feel of a uncontrolled bounce in it when empty.

I very impressed with my out lay to buy the air bags, there may be 200 pictures of cars with broken chassics, but for every one of these there is hundreds of happy customers using them.

Some will tell they never put more then 20 psi in them and others will go as high as 40 psi when towing there 5th wheels on the open road.

Sensible use of air bags in your ute will be a good investment, load levelers work fine after you get your tow vehicle set up right for towing.

Using load levelers to adjust your tow vehicle ride height is a bandage solution.

I measured my tow bar this morning before and after placing the caravan on 190 kgs it dropped 20 mil.

Hope this information is of some help as I am a real user of air bags.

patrol03 · Senior Member

It is not about load levelling.Yes it does look wonderful to have everything at the same level,but the most important thing is WEIGHT DISTRUBITION which is not obtained by using air bags. Pulling your bars up to level the the 20mm you quote Radar would still mean that your front suspension could still be not much less than 190Kg less than the rear suspension. On a wet road or in gravel it makes for an exciting time if you have to stop in a hurry. And yes, there is the the problem with extra stress on chassis points,particularly in twin cabs and having spent many years in the motor trade I have seen many unhappy customers. A professionally set up weight distribution hitch using appropriate components to suit the situation is the safest way to go not just for the caravanner but other road users too.

Radar · Guru

Hi Patrol03, yep could of paid out money to so called professionals but decided that my own experiences are better.

Tried a couple of emergency stops, the car and caravan come to halt skiding and carrying on as I would expect in a straight line, like to see how some one with more expertise would achieve a better out come.

I would also agree going to extreme pressures in the air bags may causes problems, as I had stated 14psi is reasonable even sub 20 would be good but a friend runs 40psi when towing a race car 5th wheeler Brisbane to Southern states many times per year over the last 8 years car shows no sign of bending or cracking.

The continual showing of photos displaying cars with bent chassis is not a real judgment of the damages air bags do as not all cars had air bags. Biggest problem was grossly over loading, add speed show over.

I would still think first setting your vehicle up to tow and then buy tow aids is better then spending money on tow aids first as motor vehicles are not built or sold as tow vehicles,

Tow aids are designed for once a year towers to do there yearly trip but for us that that are doing 10/20000ks a year towing they need to address there vehicle first and air bags are great way to achieve this by pumping up a little and then lowering the air pressure when running solo.

Getting back to the orignal question, how much air do you run in air bags. Most people I have come across somewhere between 10 and 18psi when towing or carring extra weight.