Trailing arm Airbag rear suspension.. Input needed

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deerefanatic

Always learnin...
Hey guys, I'm doing a cummins swap into a GMT400 (90's style) Chevy 3500. 88 model year to be exact. I'm putting a dually Dana 80 in it. It's a 2wd truck and my DD/Towrig.

I'm thinking since the spring perch distances are different between the 80 and the Dana 60 that's in the truck, I'd just go ahead and fab up the air ride setup that I've wanted for a coon's age. Here's my projected idea:

Fairly long trailing arm (prolly 4 feet or so) anchored in Poly bushings at the front. Trailing arm u-bolted to the axle. Dropped section behind the axle with an airbag and shock absorber. I know it will have a power-rise when you get on it, but I'll put some limit cables to limit how much rise it can have, and like I said, it's a tow rig, that has a gooseneck behind it quite often.

What do you all think? For lateral stability, I'll run a panhard bar to keep the axle centered.
 
I think it was on here, maybe another forum, it's been a long time but I remember seeing a 70s ford that the guy took the entire rear suspension out of a peterbilt and put in his pickup. Same setup as what you described with the trailing arms and rear bracket with bags. It would be cool to have an automatic leveling valve like on trucks. That way when you load up your bags will automatically fill. Your antisquat (rear rising) can be solved with proper planning and geometry with your trailing arms. Sounds like the perfect setup for a tow rig though, heavy duty and originality.
 
sounds like a decent setup... you 'should' be able to control anti-squat with the link geometry
 
Ok. Sounds good guys. I plan to have automatic fill valves. Possibly 1 for each side to control body roll...

My theory on the links is to make them as long as practical to control the anti-squat. Anybody have any links to some design stuff for trailing arm systems like this? There's 4 link calculators all over, but never seen anything for this type of setup.
 
Sounds like you plan on doing something like the 67-72 chevy suspension. Pretty much a 2 link with a panhard.
 
Pretty much. Should ride nice that way and handle good too......

I guess we'll just build 'er big and see what happens. Gotta decide what bags I'm gonna run
 
the 4-link calculator from Pirate will work, you just design it where there's no separation between the 'links' at the frame-side.
 
Not big enough. I need at least 3500# capacity per bag... Would rather have 4000#... This is a tow rig... Dually tow rig.
 
I gotta do some more playing around... I know the graph didn't look right. The calc I have is the Triage calc I found referenced to on Pirate4x4
 
I need to do something along this line. I want air ride so I don't have to operate the worn out jack on my gooseneck. :hehe:

The springs in my truck make it unbearable to drive. I've had several occasions on the interstate where the back tires come off the ground and the engine rpm jumps. With a heavy trailer it's fine.

I was thinking about going to F150 leaf springs, something to control axle wrap, and airbags, I like this idea better.

What about putting the bags right above the axle tube, and making a gooseneck hitch that sticks out beyond the frame and using that for the top bag mount? When loaded stuipdly heavy on the trailer the truck frame shouldn't see any of the tounge load.
 
deerefanatic said:
Not big enough. I need at least 3500# capacity per bag... Would rather have 4000#... This is a tow rig... Dually tow rig.
Click to expand...

In that case you may want to look into either going with an over the axle set up or some big rig style single bellow bags behind the axle.
 
Got er down to 166%.... Got some measuring to do on the truck and we'll get some more accurate numbers. Tire size is pretty much for certain. Axle end heights for the links are pretty much certain as well. Just gotta figure frame end heights.
 

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I know, exactly my thoughts too. Just dump er and back underneath. :)

That's my plan, to have the bags directly under the gooseneck plate.


9724VF350 said:
I need to do something along this line. I want air ride so I don't have to operate the worn out jack on my gooseneck. :hehe:

The springs in my truck make it unbearable to drive. I've had several occasions on the interstate where the back tires come off the ground and the engine rpm jumps. With a heavy trailer it's fine.

I was thinking about going to F150 leaf springs, something to control axle wrap, and airbags, I like this idea better.

What about putting the bags right above the axle tube, and making a gooseneck hitch that sticks out beyond the frame and using that for the top bag mount? When loaded stuipdly heavy on the trailer the truck frame shouldn't see any of the tounge load.
Click to expand...
 
Hmmm. I like the #4400 bags... Triple convolute. PLENTY of load capacity, and lots of travel. Hmmmmmm... Not bad on price either.
 
my system uses the #3800 spings and they are nice, it takes about 24 psi to put it at the propper height and they have plenty more to expand.
 
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