This article is about Airbag Suspension or more correctly called, “Airbag Helpers”.
It’s an important subject for you if you have or are thinking about installing airbags onto your ute.
Our aim is for you to enjoy your loaded camp trips without any misgivings or misconceptions about Airbags.
Let’s lay a bit of groundwork before we get into this subject. Trayon Campers is an off-road slide-on camper manufacturer; we make campers that slide onto tray back utes.
We do not specifically endorse the use of airbags but we are advocates of people being well informed and safe so they can have enjoyable camping experiences. Because that’s what we are passionate about.
We hope to debunk any stigmas about airbags that are not true, while including important considerations for you and your vehicle.
What this article is NOT about
As we continue our look into airbags in this article, we will be focusing on utes with airbags, not wagons with air bags!
More specifically we will be talking about utes with leaf spring suspension in the rear with the addition of airbags, we will NOT be touching on coil sprung vehicles in this particular article.
So just to re-state, in this article we will be discussing:
4×4 utes carrying a load with leaf spring suspension at the rear and the addition of airbags.
The Purpose of Airbags
Firstly let’s get something straight; airbags don’t break utes – load breaks utes.
Airbags are a handy tool, but must be used in conjunction with correctly loaded and operated vehicles.
“Airbags are LOAD HELPERS – not a tool to carry more load than intended.“
They are ideal for correcting front to back sag of the vehicle by assisting the suspension while still allowing the vehicle’s leaf suspension and chassis to do what it is designed to do – carry the load.
There are multiple variables when it comes to a vehicle carrying a load, ranging from:
- the terrain being covered
- tires chosen
- suspension setup
- vehicles capabilities as set by the manufacturer
- upgrades on the vehicle and the weight they add
- weather conditions
- load distribution
- overall loaded weight
- age of the vehicle
- history of the vehicle
- maintenance cycle of the vehicle
- brand and model of vehicle
- manual or automatic transmission
None of that is even touching on the differences in driving habits and skills from person to person. Things like driving slower over off-road terrain, deflating tires to compensate, breaking sooner, turning slower and even something as simple as throttle control and smoothness of gear changes.
Don’t Believe Rumours of the Grape Vine
So when you hear of a story from your mate down the road that got a haircut from a barber that bought a puppy from a bloke that had a coffee with a friend that heard of a ute that had its chassis broken/bent and it was caused by the airbags…..
Or when you see multiple photos of vehicles with broken chassis and the keyboard warrior regiment blaming airbags – remember to keep in mind the variables listed above and that it was not the airbag but the person using or loading the vehicle that may or may not have caused the vehicle’s chassis to allegedly break/bend.
Take these things with a pinch of salt because you don’t know the FULL story.
Was the guy driving too fast for the terrain he was on?
Where was the majority of the weight positioned?
Did he compensate for the 46-degree heat and go easy on his vehicle?
Did he blow a tyre or hit a rut?
Did he overload the down ball weight of the trailer?
Did he overload his vehicle and expect the airbags to carry the load?
Metal Fatigue – It’s Real
That last one is the key folks – overloading of the vehicle will bring about fatigue.
Possibly not in the first year or the third or the tenth (remember there are a world of variables that influence these things) but at some point, something will break.
It’s called metal fatigue; it is the invisible crux of any structure no matter how well it is designed. Ships only sail for a set amount of time.
Aircraft only fly for a predetermined lifespan.
This is due to the stresses and forces placed on all the components even down to a molecular level in base materials used, like steel and aluminium.
The same will happen to your vehicle and if you treat it harshly and increase the forces too much – somethings gotta give.
Conversely if you hear a story to the tune of “I’ve loaded my ute to the maximum for 11years now and not one thing has ever gone wrong” – remember: variables!
Pinch of salt – what is the FULL story?
Static Load & Dynamic Load – Why it Matters
If you don’t know already, the static load applied to your vehicle will increase with dynamic force when driving. This is why it is important to assess the overall load, the load positioning and the driving conditions.
A 40kg additional spare wheel and tyre can equate to over 100kg dynamic load in extreme conditions. Furthermore, this 100kg dynamic load can be further increased through leverage if the additional load is mounted at the Rear of the tailgate or canopy.
This loading and leverage example is consistent with the loads seen in towing scenarios with off road conditions, adding a raft of unpredictable variables for load and fatigue of the tow vehicle and trailer. Adding airbag suspension helpers to a vehicle will help to support the load and minimise bottoming out of the suspension from excessive compression, but does not decrease the amount of dynamic or levering load applied.
A diagram of load and load distribution with a slide on camper as the load. But can apply to any load.
Pin-Point Pressure
Leaf sprung vehicle’s chassis are designed to take strain and pressure on the leaf hanger at the front and at the rear – where the leaf is attached to the chassis, two spots.
Gaze upon my Graphic Design skills in all its glory:
The chassis is reinforced in these spots, curves are bent into the steel and in some cases, braces are put in place to handle the stresses of the weight you are carrying on the ute.
By placing an airbag in the middle of these two points, it applies pressure on a part of the chassis that is not designed to take the pressure. So when the ute is overloaded, it becomes a recipe for something to go wrong, especially if you over inflate the airbag.
Air-bag helper operation
So if you understand these two concepts:
- The Air bag helper is intended to assist the primary suspension to help maintain height.
- The Air bag pressure required is an indication of the load it is supporting.
Then it is likely you will not overload your vehicle. So how much PSI is too much pressure?
Remember there are way too many variables to answer that concisely so it is important to use the pressure as a reference of load. A good general rule of thumb is:
“Do not inflate more PSI in the airbag than what is currently in your tires”
This means – if you hypothetically have 38PSI currently in your rear tires then do not inflate the airbag more than 38PSI.
If you inflate the airbag more than what is in your tires, then you are effectively making your tires the softer part of the suspension setup and asking it to compensate for the load even though it is not designed to do this job.
Keep in mind, that in some off-road terrains (like sand driving) you should be deflating your tire pressures to compensate, the airbags should be following suit when using this rule of thumb.
But My Load is Still Not Level?
If this is the case, firstly ensure you are not overloading the vehicle.
Secondly – you probably need a suspension upgrade. A vehicle needing more than the tire/airbag pressure rule may be within the vehicle’s legal loading, but could be in need of maintenance or upgrade to the existing leaf springs.
Remember, the airbags are helping the leaf spring to support the load, so if the airbags need higher pressure it may indicate tired or under-done suspension! A constant load leaf spring of 300, 450, 500 or 600kg may be needed to allow your airbag pressure to remain at a more amicable level.
Vehicles are Built on Purpose
The vehicle engineers that designed every millimetre of your ute and set its limitations have engineered it in such a way that all the components need to work together in carrying the load; the tires – axle – suspension – chassis and tray all need to flex and compress at the same time within set tolerances (limits) as to not break something.
If you negate just one of those then the other components will be placed under more stress to compensate and this will lead to component failure of some sort, either now or in the future.
Off Road Terrain Takes Its Toll
Also keep in mind, the rigors of off-road terrain are FAR more stressful on components; especially when carrying a load – it is for this reason that a GVM upgrade is also a good idea if you are close to the limit of your vehicle’s payload carrying capacity.
This includes everything from water, fuel, 4WD accessories, people, dogs, campers, beers etc. It adds up really quickly! Check out this article which gives some real life examples of payloads.
The last thing you want is to be right on the payload limit while you are off road; you want some more wiggle room so your vehicle has a chance to do its job.
The now discontinued old design Land Rover Defender was the only 4×4 ute that had an on-road load rating and an off-road load rating which was less than the on-road rating to compensate for the added stress that off-road terrains place on the vehicle.
But these days most vehicle manufacturers just give you an on-road load rating.
Let’s Sum This Up
Airbag helpers are not a GVM upgrade!
They are not meant to cope with the entire load of the vehicle.
However, they can be very beneficial in assisting your vehicle’s suspension to level the vehicle’s ride height so your suspension can be effective in carrying the load.
You can inflate them to level the ride when you are carrying your load or towing your van. When you are not doing that, you can deflate them and they can sit there waiting for when you need them again. Airbags are a great tool which must go hand in hand with correct loading, correct suspension, sensible load positioning and driving to the conditions at hand!
