Air Bags,don't Go There

[cruising62]

HI GUYS,
I repair bent 4x4 chassis for a living, so i probably shouldn't write this post as 80% of my work comes from the fitment of air bags.
But i feel i need to help out my Earth freinds so hear goes.
We buy these 4x4s ,load them to the gunnels then wack a fully loaded camper trailer(maybe another three tonne )on the towball and serprise! the ass and is sagging. Well i'll just wack some air bags in,takes the load of the springs they say.
So wear dose the load go ???
straight on to the chassis
I've had 4x4s dragged in to work from all parts of this wide brown land at huge cost to their owners due to over loading and air bags ,some bent beyond repair with the towbar at 30 deg. bellow parallel.
The utes are the worst (Hilux,Triton,Navara,Ranger-bt50)with their flimsy 2 mm thick rear chassis.How they have a three tonne towing cap. is beyond me.Had a ford ranger just the other day cracked near threw at the bump stops.
Patrols- while the chassis are fairly strong their weak point is their rear spring mounts,they bend up into the floorpan, busting brakelines on the way&bending the body.
Defenders- (don't get me started.what a pile of sh!t) while they might look strong they are not. bending & cracking at the shocker mounts.
Land Cruisers -haven't had a bent one yet (gess what i drive).

Hope this opens a can of worms , there's alot to be said about over loading 4x4s makeing dangerous& unroadworthy...air bags don't solve the problem-if you won't to carry five tonne buy a truck.
Still have alot more info on chassis week points but thats enough typing for now.

 

[Vegetoast]

Thanks for all that info cruising62. My cruiser has been at 3tonne for about 6 years now. its on the limit, no air bags and it still sits well. You make feel lucky I sold the patrol and did the cruiser instead. Plus the patrol left me waiting for a tow numerous times and the cruiser has always got me home (touch wood).

 

[croozza]

The same thing happens to the front spring mounts on the Patrol as well, there are kits out there that solve this problem, however you can make your own as long as you are a good welder.
The Landcruiser chassis is a strong one too, but the Prado chassis is stronger again, don't ask me why a Prado chassis is stronger than a Landcruiser one, just seems to be one of those things.

 

[GippslandOffroad]

some valid points the patrol rears have been problematic for years if using wrong suspension and overloading . Seen a few cracked patrols in various other spots also
I ve had a few 8o series come thru with cracked chassis around front panhard rod mounts ,around sterring box mount and also have seen rear shocks pushed thru there mounts .
the end of the day they all break ,bend and crack when set up wrong and overloaded .

 

[Big Matt]

The utes are the worst (Hilux,Triton,Navara,Ranger-bt50)with their flimsy 2 mm thick rear chassis.How they have a three tonne towing cap. is beyond me.Had a ford ranger just the other day cracked near threw at the bump stops.

The towing rate has little to do with the actual chassis strength, the problem comes from people who don't use safe ball weight practice. To many times Ive seen trucks loaded so badly their ass is dragging, this doesn't have to mean its over loaded, it also has to do with how you load you gear. Having worked closely with a few automotive firms on strength assessment its something that prolly needs to be addressed, how ever if people cant do something as simple as load a trailer so it doesn't have hundreds of kilos of ball weight then what can you do ?

 

[Swaggie]

Thanks for the Interesting read...

 

[Big Matt]

The towing rate has little to do with the actual chassis strength

I should add to that, obviously the chassis needs some strength to support weight bearing uses like towing etc, but the towing cap isn't derived from the chassis material thickness

I bet most the people who's chassis you fix have no idea what recommended ball weight is.

 

[bmurray2250]

Very interesting reading. I have seen so many people towing a trailer with to much weight on the tow ball plus a fully loaded back of the vehicle. No wonder the chassis cracks and breaks. I have heard of a 10 -20% rule for trailer weight on the tow ball but I have always set my boat trailer to be around 40 - 60KB and no more. Makes the towing and braking much better

 

[Big Matt]

I have heard of a 10 -20% rule for trailer weight on the tow ball

When i was doing testing with 3 different tow bar manufacturers (one of which was doing OEM bars) the general idea was 10% on the ball to a maximum of 250 to 300 KG. I dont think that is the build standard though for trailers, i think that is supposed to be something like a maximum of 150KG ball weight, although i could be wrong.
When we made bend tooling for a well known trailer builder, and a very well known Caravan manufacturer i believe the maximum weight aimed for was 150, but i do seem to remember a ball weight of 215kg, but i cant be sure

 

[cruising62]

The point i was trying to make was it's air bags that make tha chassis bend &crack.
Dosn't matter if you have 5% weight on your ball,when towing a hevy trailer of road & you have sudden change in gradent the vehical springs carn't absorb the shock

 

[vitara94]

very interesting..... so all these manufactures which advertise it makes your vehicle safer its actually doing the opposite.. hmmm i have towed a trailer with 1.2t of scrap metal behind my zook but didnt do any damage(i hope) but i dont have airbags

 

[Grumpy]

This may be one of the reasons the whole fleet of DSE Patrols across Victoria are parked up at the moment, another fault with them is the cracking of the wheels apparently and the loosening of wheel nuts due to everyday use.

 

[Traveller]

The wheel cracking issue with pootrols was with the old style steel wheels for wagons, and the wheel
nut issue was with alloy rims not being at the correct torque I believe- Nissan was doing a 'safety add on' and supplying owners with wheel nut indicators....

Have run airbags in the back of mine for the last 230,000 kays and no probs as yet,(touch wood)
certainly something to be aware of though, especially with the way I load the old girl up!!

 

[cruising62]

I know what you mean Grumpy,have herd of the Trols wheel nuts comming loose.
have just repaired the Casey council's fleet of BT50,s all with air bags and bent & cracked at the bump stops,after they have finished with them & want to sell them- they wont be buying BT50,s again. I pity the new owners -buyer beware.
ps, how can i get contract to fix all the DSE,s patrols maybe then i could retire lol.

 

[teza h]

Well I think the point here is that people just expect too much from the vehicle, some of the loads that you see on 4by's is unbelivable, so when the after market suspension cant take the load of all the sh#t that people must have to get into the great out doors, you just simply stick on some airbags and then hit the rough tracks, the load on the vehicle when it is crawling and twisting over those rocks and ruts must be tremendous. It's realy no wonder that they break.
I agree with Cruising 62 when he said, if you want to cary 5 ton get a truck. Modern 4by's are not design'd to carry those kinde of loads.

 

[cruising62]

hay Travaler, have you had a close look at your rear spring mount brackets ?
check the clearance between the top of the mount and the floorpan-they have a habit of squshing the fuel & brake linens on the right hand side-stupid place to put them.

 

[cruising62]

yep, and the more modern they get the less they can carry

 

[Big Matt]

The point i was trying to make was it's air bags that make tha chassis bend &crack.
Dosn't matter if you have 5% weight on your ball,when towing a hevy trailer of road & you have sudden change in gradent the vehical springs carn't absorb the shock

I understand that, the point i was making is people make the issue a lot worse by loading the weight wrong then relying on airbags to level the vehicle

Its just stupid really

 

[GippslandOffroad]

So does this mean every single patrol with airbags will have bent rear spring pearches and evry single jap ute with airbags will have bent and twisted chasis from there airbags mmm dont think so and evry bt50 is goin to be bent and twisted .or is this just a panic attack thing .
Sorry traveller for jumping in on you ,no last time we looked the spring perches were rite where they should be .
We have fitted a few airbags to coils and leave sprung 4x4s and never had an issue ,and still maintain we have had more cracked cruisers than patrols thru the door and yes had craked patrols also .

 

[Traveller]

Mo worries Matt, was just thinking that we talked about them a few weeks ago!!