air bags under a 67-72 burb?

[benscool1]

Anybody have pics and details of their bagged burb? How much did it cost you, are you running a 4-link, etc.?

[ghetocrewzer]

I replied in the other thread with some pics. I just bagged mine on the factory 2-link just boxed it and put a loner adjustible panhard bar on. Mounted the bags further forward than were the springs mount for more lift.

[benscool1]

What kind of rear suspension do 67-72 burbs have from the factory? Can you put bags under it w/out any serious mods(like customizing cross members)?

[ghetocrewzer]

Suburbans have a factory 2-link w/ a panhard bar. Airride Tecnologies makes a complete bolt-in airride setup w/ bolt-in notch for these trucks. It lays them down preety low within about 5 inches from the ground.

[DUBURBAN]

There are many options available. You need to decide how low your trying to go first. There are allot of aftermarket parts availabe but you still will need to modify somethings on your vehicle. My 71 Suburban is currently being dropped to the rockers on 22's. The frame work and suspension has been very extensive. Everything is being custom fabricated. The most most extensive work on these models tends to be steering. I've purchased tubular uppers and lowers to help. The frame and horns are being Z'd approx. 2 1/2 inches and the front cross meber is being raised another 1 1/2 inches. All in all the front will be dropped around 10" andwill keep correct camber. The rear is utilizing a 96 Impala SS disc rear and a custom 2 link. The tires actullay rest about 2" below the rear gless and the front should be about 1/4" from the underneth of the hood. Good luck. Let me know if I can help.

[KutThroatKustoms]

Please dont bag on the stock 2 link. Yes, shops do it, feature trucks have it, but bags on 2 links are even more notorious for buckling the bars, especially 30+ yr old bars. Get a 4 link or buy ART's airbar for the truck. I'd say 4 link it, notch the frame and sit the suck flat on the ground.

[darcane]

Originally Posted by KutThroatKustoms

Please dont bag on the stock 2 link. Yes, shops do it, feature trucks have it, but bags on 2 links are even more notorious for buckling the bars, especially 30+ yr old bars. Get a 4 link or buy ART's airbar for the truck. I'd say 4 link it, notch the frame and sit the suck flat on the ground.

How would air bags on the stock trailing arm suspension be any harder on the trailing arms than the coil springs? I've never heard of the stock trailing arms buckling with airbags or otherwise.

[KutThroatKustoms]

Originally Posted by darcane

How would air bags on the stock trailing arm suspension be any harder on the trailing arms than the coil springs? I've never heard of the stock trailing arms buckling with airbags or otherwise.

Your stock springs dont push and put stress on the bars. springs are a steady rate. Air bags with more air, push down, putting more stress on them.

Yes, you boxed them.. okay? Extensives 2x2x3/16" 2link setup has buckled before. I;'ve been in an s10 and we airred up to clear a bump coming, hit the bump in a 45 and it bent one of the bars, b/c with so much the bar doesnt have as much give as say a spring on it would.

[ghetocrewzer]

I am sure if you mounted the bag at the pivot point(cantilever) it would put a whole lot of stress on the bars and maybe buckle them(but probally not). How is a 4-link with the bags mounted o bars any better??????

[SCOTI]

Originally Posted by KutThroatKustoms

.... springs are a steady rate. Air bags with more air, push down, putting more stress on them.

True, most springs are linear. But springs (coils) are also availible in differing rates.... both soft & harsh/stiff. Adjusting the air psi of a bag is no different than swapping out stock springs for drop springs or springs w/a different rate. Where did you find the info that an airbag @ a given psi has a higher spring rate than an interchangeable coil spring?

Yes, you boxed them.. okay? Extensives 2x2x3/16" 2link setup has buckled before. I;'ve been in an s10 and we airred up to clear a bump coming, hit the bump in a 45 and it bent one of the bars, b/c with so much the bar doesnt have as much give as say a spring on it would.

An S10 w/Extensives 'style' 2-link is apples to oranges vs. a 60's -72 truck 2-link. Where was the spring mounted in relation to the 2-link? Most of their kits IIRC mount the spring towards the front for more 'lift', & they're mounted parrallel to the frame unlike the truck arms.


If one were concerned w/the possibility of 'buckling', it's easy enough to gusset the truck arms w/o much effort. The truck arms are designed just like steel I-beams for a reason.... because they're strong. The weak link for the truck arms is they're 2-halves tacked/welded together. Laying down a decent weld bead every 6" will fix that. Still worried? Cap the top/bottom by welding simple & effective reinforcement plates.

Unless there's another reason besides function, the truck 2-link works just fine.... even w/airbags. Strong? My truck, lowered enough in the back that the pumpkin has clearanced it's own access hole in what's left of the rotted wooden bed floor, pulls my 18ft car hauler (w/another swb truck on it) w/o problems.

[Slammed67]

Your stock springs dont push and put stress on the bars. springs are a steady rate. Air bags with more air, push down, putting more stress on them.

Uh? So what happens when you hit a bump on the road with a coil spring truck???

Actually, I'd think an bag would be easier on the trailing arm because of the greater surface area (bag plate/bracker) it comes in contact with as opposed to the end of a coil spring.

[darcane]

Originally Posted by KutThroatKustoms

Your stock springs dont push and put stress on the bars. springs are a steady rate. Air bags with more air, push down, putting more stress on them.

So, what you're saying is that when the truck is sitting there, not moving, the force on the trailing arms increases as you pressurize the bags? i.e. at 50psi in the bags the force pushing down on the trailing arms would be X and at 100psi the force pushing down would be about 2X?

[LONGHAIR]

When the truck is sitting still (assuming that you are not pushing against an upper travel limiter) there would be no difference. The weight of the truck is the same, so the incerased air pressure just makes the bag taller, thus raising the truck. It is when the truck is moving(or loaded) that the increased pressure would act as increased spring-rate too.
A bump that would force the axle to be deflected upward with a lower air pressure would apply that force to the entire weight of the truck if the bag had greater pressure.
The force involved is dependant upon the placement of the bag. The closer the bag is to the pivot point, more force is applied to the trailing arms. As the bag is moved closer to the rear axle itself there is less force applied to the trailing arms, but you get less lift.

[benscool1]

Don't you have to cut a hole in the floor to lay frame though? And do you have to raise the crossmembers as well?

[ghetocrewzer]

Depends on how much money he wants to spend, I boxed my stock bars and bagged it on them. Guess what no buckling, noone told him to just bag on the bars I said you have to box them. I did mine this way to get by a while before I 4-link it and it works. And I did supernotch it but just doing that won't lay these trucks flat. You've also got to raise crossmembers and either z the frame, raise crossmember, or just bag it and bodydrop. I raised my crossmember 1.5", rebuilt tranny and swing bearing crossmembers, and it still likes 1/2 inch laying pinchwelds flat. So i suggest z-ing the frame to lay all the way out. I'm going back and z-ing mine 2" and am cutting off part of the rockers. Not trying to discourage use of 4-link just giving him lower dollar approach. LATER

[benscool1]

Thanks ghetto, lower dollar definitely is the approach I need but while not sacrificing quality. I think boxing in the bars will be what I do. What kind of drop can I do in the back before I have to notch? And if I notch the frame will I have to cut into the floor immediately or do I only cut in the floor if I do an extreme drop? I plan to only do a static drop immediately, maybe 4in coils in the back w/1.5in blocks and 3in coils in the front w/2.5in spindles or does that not sound right? Would I be able to do that w/only a c-notch and not cutting the floor?

[benscool1]

BTW, what does it mean to Z the frame?

[Slammed67]

How would air bags on the stock trailing arm suspension be any harder on the trailing arms than the coil springs? I've never heard of the stock trailing arms buckling with airbags or otherwise.

I was wondering the same thing.

[smokekiki]

I would tend to think You just need to make sure Your trailing arms are in good shape and not rusting.This goes for springs or bags.After all a loaded truck can be pretty heavy,and not have to worry about the arms buckling.How many trucks and burbs that are on air carry any loads?

[Sublvr72]

Originally Posted by benscool1

BTW, what does it mean to Z the frame?

"z'ing the frame" reffers to an old hot/rat rod method of lowering the front of a car. They would cut the frame before the engine mounts and before the front suspension. And also cut the frame after the engine mount and the front suspension. They would jack that section up a few inches and weld it back inplace. this lowers the car, raises the engine, and acts like a dropped crossmember so now you can do your drop spindles and coils and have a really, really low ride. Check out IF customs website, I believe they did the z'ed frame to a 66 suburban to clear 22" wheels

[benscool1]

The 64 Suburban? Can you do this to the rear suspension/frame as well?

[Sublvr72]

Originally Posted by benscool1

The 64 Suburban? Can you do this to the rear suspension/frame as well?

I am sure you could but I dont think it would be engineered like its supposed to be. The conventional way is to do a stock floor bodydrop if you really want to go that low

[KutThroatKustoms]

The more air in a bag, the more the "spring rate".. so dep[ending the bag in the back, ride height could be stiff or soft. Depending if you show up and raise the back all the way up, etc. The more the air the stiffer the bag.

Ghetto - that isnt a cantilever... a cantilever has a rocker and pivot point. The bag on bars is a Mechanical Advantage Lever set. As for your 4 link question, 4 bars distribute the weight, not just 2. Yes the 2 links of now a days are different then the truck back then. But a 2 link is a 2 link. If it works, use it :shrugs:.. As for the 4 link question. Easy, a lot of the 4 link bars are a) gussetted like on KP's kits or they're thick enough to handle it, like on sd.com's stuff, 2x2 box 1/4" thick. The ppl that dont gusset their bars or run thick stuff like Jason makes at sd.com are looking for problems. I've seen acouple trucks, yet again, another s10, this time a 1 st gen, used a FBI universal 4 link and it bucked the bars. b/c of the downward force.

air bags push DOWN, the air enters at the top and it pushes down, which pushes the rear end down and the frame goes up.

There are different spring rates, but non are on the fly change, why else do you think Firestone 2500 bags with enough air to say, untuck 18's on a smaller truck is so bouncey/crappy ride? b/c its a stiffer rate b/c there is ~120+psi in them. With the bigger bags, its less air for a certain height = softer rater = better ride. Depending your bags using. Slam Specialties bags are stiffer then most in nature, not ride, but a stiffer bag in general also.

If your truck tows with the setup.. cool. But some trucks use 2"x2" frame for stock floors.. but i guess since it hasnt fallin apart, its "right" to do, even tho its deflection is more then stock (i know we're not talking about bd's, but its the point that matters).

[XXL]

Originally Posted by KutThroatKustoms

air bags push DOWN, the air enters at the top and it pushes down, which pushes the rear end down and the frame goes up.

Originally Posted by KutThroatKustoms

If your truck tows with the setup.. cool. But some trucks use 2"x2" frame for stock floors.. but i guess since it hasnt fallin apart, its "right" to do, even tho its deflection is more then stock (i know we're not talking about bd's, but its the point that matters).

[Slammed67]

air bags push DOWN, the air enters at the top and it pushes down, which pushes the rear end down and the frame goes up.

You have some interesting theories. So if the air inlet/outlet was on the bottom of the bag, it wouldn't work??? Would it instead push the rear end down through the ground? Doesn't matter where the air comes in at, the result will be the same..... it's AIR.

Isn't the truck trailing arm design called a 3-link? Two arms (2) and a panhard bar (1)? It's a very simple well designed suspension. Ever seen a NASCAR chassis? Same thing.