Air Bag Suspension?

[Bawshawg]

Hey everybody,

Long time creeper - first time poster.

I've got myself an LC80 HDJ81 from Japan currently for towing my racecar around. It works great here in the prairie provinces, however it's undergoing some serious elbow grease over winter in order to bring it up to snuff for hauling to the states!
(Cummins 5.9, 5spd, Dana 70 Axle, etc.)

I'm curious to know if anyone has insight on Tow Bags or Air Suspension that I could install in the rear?

Theres lots to choose from for other vehicles, but I'm thinking there will be some fabrication involved in adapting such applications to the Toyota.

Do any of you have a preferred brand, or suggestions?






Thank you very much,
-Spencer.

 

[98 SNAKE EATER]

Are you looking for complete replacement air springs or just helper air bags?

 

[Kjartanbj]

I have firestone 1600kg bags in front and rear , custom built under it

 

[Bawshawg]

Just helper bags I believe.

So I'll be running aftermarket springs and struts as per usual, but then the bags can be filled with air when I hook up my trailer.

Are they capable of holding up to a 10,000lb trailer being towed?

 

[Devil's Slide Doug]

I am using airlift #60755, 10.5" tall to work with a ome 2.5" medium lift. They fit inside the coils. Very easy install.

 

[greentruck]

Just helper bags I believe.

So I'll be running aftermarket springs and struts as per usual, but then the bags can be filled with air when I hook up my trailer.

Are they capable of holding up to a 10,000lb trailer being towed?

Aye, and there's the rub. With the factory tow package -- essentially, the frame-mounted hitch -- the tow capacity of the 80 is 5000 lbs.

You're wanting to tow about twice what the truck is rated for. I think power-wise, you'll be fine once the Cummins is in. Braking may be covered with a good controller and decent trailer brakes, but I dunno. Suspension is gonna be the weak point. I'm pretty sure none of the helper bags are rated for 5000 pounds above the tow rating.

This might indeed be a place to consider a rear full bag modification, as I don't think there are any coils rated for 5000 lbs over-capacity, either.

You'll be pushing things to the limit to tow a 10K trailer with an 80, even with a diesel up to the task.

 

[98 SNAKE EATER]

Just helper bags I believe.

Here's a link to my old AirLift bag installation thread

https://forum.ih8mud.com/80-series-tech/229469-anyone-running-rear-helper-air-springs-their-rig.html

So I'll be running aftermarket springs and struts as per usual, but then the bags can be filled with air when I hook up my trailer.

Are they capable of holding up to a 10,000lb trailer being towed?

You're really exceeding your limits with a trailer that heavy


That being said, the bags are only good for an extra 1000lbs. load

 

[Bawshawg]

Interesting,

Thats what I was wondering - as I've seen bags that are rated for 1000, or 2500?
So does that mean that even loading a 3000lb trailer would pop them? This stuff is completely new to me, so I'm not certain as to how they are rated for strength.


10,000lbs would be the absolute maximum. As for suspension. I do currently have the OME heavy duty 4" lift springs in the back, it helps quite a lot and still is very jacked up in the rear whilst hauling 6000 or so. However it rides like a cloud with load, without a trailer it bounces like crazy.

We're just looking now at 20ft - 24ft enclosed trailer + 3000lb racecar + 1000lb of gear, tires, tools etc.

The frame will also be heavily braced where possible, shouldnt be too difficult to do a couple big X's here and there.

 

[Bawshawg]

Come to think of it, with the Dana 70 Rear axle - it should make things a little different but potentially easier to adapt for larger tow bags or different style?

Chances are I'd be adapting the Dana 70 to work with the stock LC80 spring and strut setup, rather than the other way around.

 

[chairborne]

Just helper bags I believe.

So I'll be running aftermarket springs and struts as per usual, but then the bags can be filled with air when I hook up my trailer.

Are they capable of holding up to a 10,000lb trailer being towed?

Tongue weight is not the same as trailer weight, at all. How many axles? What length? Level with the hitch? Lots of factors to consider.

 

[Paul_L]

I'd get a truck that is rated to tow that kind of load. The 80 in N. America is only rated at 5k lbs. I've read some threads that indicate in other countries it might tow up to 7k lbs. You're looking to exceed even that number by 3k lbs, a dangerous situation IMO.

My friend who tows an enclosed trailer with a '74 Datsun 240z vintage racecar moved from a 1500 gas Silverado to a 2500 Diesel Silverado & said it's the smartest thing he's ever done.

 

[Bawshawg]

I would tend to agree Paul, the HDJ81 from Japan is capable of hauling 10+ according to a few of the local guys who take it out to the oilpatch or campsites etc.
I've owned several HD 2500 or 3500 series trucks in the past, and despised all of them.

Most likely a tandem axle pretty straight forward enclosed trailer. 24ft would be the maximum, 20ft would be the minimum.


I'll try my best to make it work - I still think its not such a far fetched idea.
Would be way nicer, and far more comfortable than any of the other huge American tow rigs Ive owned

 

[Paul_L]

Here are some pics of my buddy's custom trailer - I believe it's 24' Don't know the weight but I could find out.

I wouldn't even try to pull it with my FZJ80. BTW his truck is very comfy.

 

[Bawshawg]

I wouldn't be overly afraid, but definitely cautious. I've got a wicked trailer brake controller, and anti-sway hitch setup.

However that thing is probably quite a bit bigger than what I'd be grabbing. It's definitely beautiful though!

-Spence

 

[Grench]

There are several factors to consider when setting up to tow with any vehicle.

Among those, these are pretty important.

Trailer net weight.
Trailer tongue weight.
Trailer brakes.
Tow vehicle weight.
Tow vehicle power.
Tow vehicle wheelbase.
Tow vehicle weight distribution.
Tow vehicle hitch rating.
Tow vehicle brakes.

Trailer net weight is going to be an issue right off the start. A 10,000lb trailer doesn't like to turn - and can push the 5000lb cruiser (6000lb with your mods) all over the place under braking. This can lead to a jackknife at speed scenario.

Trailer tongue weight. This is the down force of the trailer at the ball connecting it to the tow vehicle. Too much tongue weight and the front end of the tow vehicle gets lifted up using the rear wheels as a fulcrum. IIRC the 'stock' frame mounted hitch maxes out at 500lbs tongue weight - and assumes a mostly empty rear cargo area. Drawtite makes an aftermarket hitch rated at 600lbs tongue weight, but on a 10,000 pound trailer, you're going to want at least 10% of that in tongue weight. Too little tongue weight and the trailer can LIFT the back end of the truck up in the air when you're going over relatively benign lumps in the road.

Trailer brakes - pretty much a must have with any trailer over 4000lbs IMHO.

Tow vehicle weight. Generally you'll want the tow vehicle to weigh at least 50% of the trailer weight if you're going to use a standard hitch - goose neck trailers on bed hitches in front of the axle are a different story as they increase the tow vehicle weight.

Tow vehicle power. Can it reliably pull enough to reach highway speeds? Does it have enough engine braking capacity to slow the whole thing down going down grades? Remember, if you're using your brakes to maintain speed going down the side of a mountain then you're doing it wrong.

Tow vehicle wheelbase. This is a big place where the 80 is a failure as a heavy tow vehicle. It's relatively short wheelbase means that the trailer will have an easier time of pushing it around sideways.

Tow vehicle weight distribution. This is a system using additional bars from the hitch to the trailer to use leverage to move the hitch weight forward to the tow vehicle's front axle - effectively increasing the net weight of the tow vehicle. The 'stock' hitch and arguably the 80 itself are not designed for weight distribution. The aftermarket Drawtite hitch claims to be rated for weight distribution, but maxes out at 600lbs hitch weight and 6000lbs towing WITH weight distribution.

This is where air bags wind up being primarily a cosmetic fix. Without a weight distributing hitch, the rear end of the truck is overloaded causing a visual effect of the rear of the truck sinking - which is only half the story. The front end is also being lifted - using the rear axle as a fulcrum. Adding bags to the rear springs lifts the rear end of the truck - the fulcrum point - up to make it visually better with the lifted front - but results in the front of the truck still being 'unloaded' - i.e. the tongue weight of the trailer AND the portion of the front of the truck that it lifted over that fulcrum is now all riding on the rear axle. By unloading the front axle it can become dangerous as there is less holding your front tires on the ground - and making it more likely that the trailer will push the tow vehicle all over the road.

Essentially, putting an 800-1000lb tongue weight trailer on an 80 would raise the front end 2-3", puffing up air bags to match raises the back 2-3". Visually the body of the tow vehicle is flat - but the weight dynamics have unloaded the front axle by ~3-400lbs, raised the center of gravity by 2-3" and seriously overloaded the rear axle, now carrying the equivalent of 1400+ lbs more than it normally does.

This website has a good example of how trailers change the dynamics of the tow vehicle with and without weight distribution.
http://www.etrailer.com/faq-weightdistribution.aspx

They have a nice diagram with red arrows showing the dynamics of without and with a spring-loaded weight distribution hitch setup. Airbags are exactly the same as the picture without a distribution hitch except an additional red arrow would be pushing up directly at the rear axle of the two vehicle - not changing the unloading of the front axle - just making the net vehicle taller.

The short answer - find something else to tow that monster trailer with - or build an 80 series 6x6 with a longer wheel base and custom load distribution hitch...

 

[Bawshawg]

Very interesting.

Lots of variables to consider.

Towing 6500-7000lbs has already seemed rather effortless, however that was with a Uhaul auto-transport which is relatively small. I think they're 18feet or so.

A Toyota die-hard, very much trying to avoid selling my favourite truck of all time in order to get some longbox dodge crap.

 

[Paul_L]

I've got another friend who is very happy towing with his late model Tundra - 5.7l V8, 4x4, Double Cab, but he only tows about 5K lbs. max. Rated towing capacity - 10,200 lbs.

 

[Grench]

Very interesting.

Lots of variables to consider.

Towing 6500-7000lbs has already seemed rather effortless, however that was with a Uhaul auto-transport which is relatively small. I think they're 18feet or so.

A Toyota die-hard, very much trying to avoid selling my favourite truck of all time in order to get some longbox dodge crap.

A dream of mine that I don't have the time, fab skills or space to build...

Take an FZJ80, chop the top off after the 2nd row to make an extended cab pickup style - but extend the frame at the top of the rear wheel arch back far enough to add a 2nd rear axle. Cut and flip sides on an axle so that the pumpkin faces backwards. Drop a dual range transfer case between the rear axles running off of the drive shaft output from the stock t-case. Part time the front end with ASIN hubs. Put a deck mounted goose neck trailer ball in the bed just forward of the rearmost axle.

FZJ80 6x6 with high 6WD, low 6WD, double low 4WD (rear tandems only) and capable of pulling a ~15,000 pound goose neck trailer. With all 3 axles and both transfer cases locked - it would be pretty well unstoppable if un-steerable.

Free idea - but if you build it, I want a ride.

 

[scottryana]

I think everything is able to be overcome except for the short wheelbase. I have seen guys with 80's tow ridiculous loads that I wouldn't, but it has been done. I have seen a 28' enclosed trailer towed behind an 80 without airbags or trailer brakes. It was in the flats so no mountains to climb or brake down. I am going to be in the minority here, but I will tow more than 5,000lbs behind my 80. I will try and keep it close to that but I have had no problem up to 8,000lbs.

 

[Bawshawg]

Grench, sweet idea!
I dont think I'd want to tear apart my LC that much though, I've only got one off season to get this all done.
Which shouldnt be too tough.


Scottryana,
I'd probably agree with you - I dont think I'll be doing much mountain towing for stateside stuff, as in Alberta we can snake through some of the northern states to cut the drivetime down.

However, I suppose as long as I try not to get some massive ridiculous trailer behind it, and a load distributing hitch, other safety stuff, big tires, trailer brakes, landcruiser brakes, the works... 10000 I'm thinking wont be ridiculously out-to-lunch?

The short Wheelbase of the LC80 is apparently 112"
For arguments sake...
My old Duramax was 119" and hauled huge stuff all over the place.
(Yes I'm aware it's far more designed to do that, than a Toyota/Lexus off-road SUV)
I do also have a pal of mine who had some immense V8 in his Suburban and was hauling his 30ft race trailer from Quebec to LA for events. Seemed sketchy, and expensive... but he was doing it quite frequently.

The Dodge Rear Axle swap is a must though, yeah?
No way a stock one would hold up to that strain?
-Spence