Leaf/airbag hybrid lift

[oldchevy4x4]

Ok I am starting with a stock 84 c20 with 305. It's going to get fuel injection on a 454, 5 speed, fabbed extended cab, and custom flatbed. But this is about my suspension.

Ok so what I want out of my suspension is:
First goal is go-fast. So decent travel for off-road and good cornering for on/off road.
Secondary is mud/crawling. The lift advantage is all I need. The mudding and crawling ability I get from some lift and 500+hp goal is enough.
Plan lift goal is ~4" with 37" military take-offs (with whatever trimming needed).

So my plan is to take rear leafs (64") from the back of 2 1500 88-99 truck for my front and rear (shackle flip in rear). Then use high Tavel air bags all around for added load capacity/ride characteristics. I was planning to remove a few leaves in the front to make use of the bags. Then I'll add onboard air for changing as I go.

I am mostly looking for a good air bag to use (hopefully around 12-14" of travel) and any pointers from/see if anyone has done something like this before.

Also for cornering obviously I need sway bars. I was thinking about making the sway bar mounts just be cupped pads and add a air bag in the middle to pull it into the cups. That way it functions like normal but when one tire cycles without the other it won't damage anything. Then if crawling or such the bag can be aired down and act like a sway bar disconnect but it's at the frame instead on the links. Is this crazy? Problems I might encounter with it?


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[oldchevy4x4]

Correction to my post. I'm going to run the rear springs (56" I think) with some leaves removed in the front


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[oldchevy4x4]

Man did I confuse everyone or am I just that out there that no one around here can help? Might have to go over to pirate on this one[emoji48]


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[87scotty]

Well im switchin from 350 to 454 500hp 500 tq and was thinkin bags on rear ive got 7inch lift 4 spring 3 body done by po but i was gonna make my bags kind of a quick attach so when im heavy hauling i can have the help and stay level but want to take em out when out playin i dont think bags will hold up well offroad and aired down

 

[oldchevy4x4]

I know there are a decent amount of guys running bags on like tube buggies and stuff so they should be ok. The goal would be not to have enough leafs in the springs to have them aired down to far (maybe 10psi range).


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[oldchevy4x4]

Hey to anyone that's interested in this. I ask over at pirate and a lot of guys said that by the time you remove that many leaves axle warp would be a big problem. So then it would need bars to stop this, now it's basically a link suspension. So I'm going to use the ORD 4 link kit and use air bags instead of coil overs. I emailed them and he said that without the coil overs it takes 1200 off the kit


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[87scotty]

So total price comes out to be....?????

 

[oldchevy4x4]

2000 and something. I think it was 2200


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[theblindchicken]

I wouldn't use only air bags for the suspension. You will not have the dampening that comes along with a set of shocks and/or coilovers.

The air bags will probably hold the weight fine, but in a dynamic setting (every day driving), it would probably be akin to driving on a leaf spring suspension without any shocks. May be passable for smooth streets only, but I would not trust them on any uneven surfaces or hard driving.

For the scenario of using a 4-link system solely utilizing air bags (no leafs, and/or coilovers):

With your first goal of "go fast off road", coilovers and bypass shocks are necessary for the ability to tune the dampening and rebound. I don't see where this adjustability exists if you were to use only air bags.

Second goal, sounds like it would be fine for mudding since the suspension is mainly geared towards height, not necessarily suspension flexing. Crawling on the other hand, sounds like it may be an issue since you want a lot of flex. Lowering the pressure to allow for a flexier suspension sounds like you would also be lowering the ride height, thus reducing you overall clearances and more chances of getting stuck and/or binding up your steering and tires in the wheel wells prematurely.


My recommendation:

Option 1:

If you insist on using air bags, I would recommend that you maintain atleast the main two leaves from a spring pack to center the axle and use the air bags as the main weight carrier. This will create a ton of axle wrap that can be correcting using traction bars. From here, you could decrease the pressure in the air bags for your faster offroad situations while also having a nice set of remote reservoir and/or bypass shocks. Probably the cheapest route, but no idea what LT air bags cost


Option 2:

Disregard the air bags. Lengthen the rear spring hangers to allow for 56" or 64" springs. Purchase a long travel set of springs (such as deaver, alcan, All Pro, etc.) and run a set of higher end shocks (remote reservoirs and/or bypass shocks). Probably middle ground expense

Option 3:

4-link it with coilovers and smooth body/remote reservoir shocks. Probably most expensive option

 

[oldchevy4x4]

I guess I should have said I was going to run shocks. I just completely forgot to mention it. I was planning on a middle of the road high travel shock (probably remote reservoir) which I know will probably bring the price tag up to the same as coil-overs. But I've always liked the idea of air ride so I will probably end up running it. (Even though it might not be the "best"). I especially want it in the rear as it will be used for towing too and I really want to be able to level it under load


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[theblindchicken]

I guess I should have said I was going to run shocks. I just completely forgot to mention it. I was planning on a middle of the road high travel shock (probably remote reservoir) which I know will probably bring the price tag up to the same as coil-overs. But I've always liked the idea of air ride so I will probably end up running it. (Even though it might not be the "best"). I especially want it in the rear as it will be used for towing too and I really want to be able to level it under load


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In that case, why not keep the couple of main leaves to center the axle. They won't be holding much weight, which is where the air bags would come in. Run ladder/traction bars to counteract the axle wrap. Shocks from axle to outboard shock hoops still inside the wheel wells. Then either mount the air bags from spring plates to frame or run them inboard the frame?

In my head, this would be a bit of a halfway point to a full 4-link setup since ladder bars would mount to about the same point as the lower links would. Minus upper links that will also center the axle and prevent axle wrap. Air bags mounted similarly to a pair of 1:1 coilover setup.

So the leaves will locate the axle, ladder bars to fight the axle wrap, air bags to hold the weight, and then shocks for dampening and tuning of the suspension.

 

[oldchevy4x4]

Just to make sure we're on the same page that's what I'm planning in the rear. My thought in the front though was that by the time I build ladder bars in the front along with adding the air bags I already built half a link set-up. So for the same amount of work I could get a link kit and ditch the leaves. In my head that made the most sense but I'm not saying I'm right. It would probably be easier to fab ladder bars than add links I suppose but I would have to rebuild the spring mounts though for the longer springs. But I could probably build it for less money though too.

Sorry if this question I'm about to ask has been covered a lot but I thought of it once I was already typing. For anti warp bars in the front how do you go about setting them up? Since the axle would move back slightly as it cycles you can't run them behind it can you? and wouldn't they be in the way in the front? This is the main reason I was just going to go with a link set up in the front


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[theblindchicken]

For the front and rear, you would need probably need to run a ladder bar with shackles at the frame mount to allow for any horizontal movement of the axle during cycling.

With a hard mounted pivot point, it would bind up your suspension greatly whether in the front or rear.

May or may not have an issue with everything getting tight together in the front though. Need to break out the pvc and cardboard tubes for mockup.


I agree that a 4-link system may not be the simplest or cheapest option, but will definitely allow for a huge tunability for the smoothest possible ride.

 

[oldchevy4x4]

Ah ok that makes sense. That's what I always wondered about ladder bars but since I mostly only see them on pull trucks and stuff I assumed that they just worked like that but a shackle with rod end style joint on one end should make them flex good. So yeah I'm going to have to mull it over some more, back is definitely staying leaf with ladders if/when I have problems and I'm really on the fence for the front. I'll have to get under there again and look around to see what I can come up with


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