Custom AirBag Rear Suspension Plan - Worth It?

[BajaCruiser94]

OK, so I did my homework and studied most of the relevant posts for air bagged rear suspensions; still the final answer is somehow blurry; do the air bags limit suspension travel while flexing off road? Responses normally are biased and/or not clear.

Here’s the deal, I have the 2.5” TJM suspension with gold shocks, front 25mm spacers and 305’s all around; I know the springs are progressive rate; no armor nor custom bumpers (yet!)

Problem is, when loaded with people and gear the sag is noticeable; and most of the trails I travel down here in Baja make the rear hitch dig deep into the ground causing chills on all passengers.

Anyway, here’s my plan up for discussion and/or destruction.

Elements in mind: AirLift/TJM or Firestone airbags + PUMA Compressor +2 solenoids + current un-used antenna up/down switch

- Normal Air Bag installation, inside springs, cutting bump stops.
- First solenoid used for inflating/deflating both bags, air input coming from compressor manifold
- Second solenoid to toggle between “T” setup and isolated bag setup (more details below)
- Antenna Up/Down Switch wired to the first solenoid for inflation and deflation
- Small toggle switch for “T” setup and isolated bags

Reading in past posts, there’s a lot of debate on “T” setups and isolating bags; both have pro’s and con’s depending on the situation.

T Setups in my understanding can work off road, one wheel flexes up, air is transferred to the opposite side; and there’s no significant added restriction to the normal articulation.
Isolated Bags, on the other side, can work on road and on higher speeds, where sway caused by weight and handling can benefit from stiffer bags when air is restricted inside each one.
Once again, this based on my understanding, maybe I’m wrong, maybe not?

On my proposed setup, a normal solenoid will be used to inflate and deflate both bags, and when isolated bag setup is desired, the second solenoid will just cut one bag from the system; of course, inflating and deflating will have to be with the T setup always; I’ll figure out how to do this with some wiring and relays; at least I hope so.

Before I start investing additional time, money and a lot of sweat (115F Weather) I wanted to run it thru my masters in IH8MUD; is this feasible and worth it?

Thanks.
-Emerson

 

[bignasty]

I would ask Cody since he is one of the few that has a full air bag suspension. Cody has a Cummins powered land cruiser on 37inch tires. To answer your question about limiting suspension, You can use limiting straps to keep it from over extending the bags. I will be copying his setup very soon because that suspension gives you infinite options.

https://forum.ih8mud.com/threads/codys-slow-white-80-re-build.407556/#post-5802881

 

[artech]

I'm in the middle of installing this setup right now, only without onboard air. I'm going to do a writeup when I'm done. I'm using a solenoid valve to make the bags either separate or connected, and I'll have to open that valve when airing the bags up or down.

I have my bags in and running separately right now, I have a gauge mounted in my console to keep an eye on things, and the electric valve and all the parts to connect everything. Now it just needs to stop raining long enough for me to finish it up!

 

[ppc]

Yes, air bags will limit flex off road as it is suggested that you run 5 psi minimum in the bags at all times to keep the bags from being chafed and pinched. You can run less but you might be replacing the bags at some point.

As far having them isolated from each other, I understand everyone has different requirements, but I recommend keeping them plumbed together. If your truck is leaning to one side then re-balance the load. If you use the bags to level side to side then you effectively have different spring rates which can be dangerous when your driving down the freeway and hit an big bump or expansion joint. Different spring rates will have a tendency to throw the truck side to side rather than just up and down. Off road, when one spring compresses it will force more pressure into the opposite bag which tends to level out the truck more so than if they are isolated.

As far as the plumbing keep it simple. In my opinion the solenoids are going to be the weak links. Mechanical valves are the way to go. I had remote control kits installed for both AirLift bags and Rancho adjustable shocks. To remove pressure they both used a schrader valve mounted on the console connected to the pressure line. The pressure line is already inside for the gauges any way so only a tee and small length of tubing is required. Don't have to mess with switches and running wires.


In the picture you see the schrader valves mounted in front of each gauge, the black and red push buttons run each of the little compressors.

 

[scottryana]

I disagree on plumbing them together. Atleast for on road towing and hauling. It is a chain reaction type of scenario when you are heavily loaded and corner or load shifts or anything similar just when you need what you installed the bags for which is an increased spring rate and resistance to compression, you have a system where the air in the compressed bag rushes out the path of least resistance and pumps up the other bag, pushing harder on the bag on the corner causing more air to rush out, further inflating the inside corner bag, wash rinse repeat. NOW can you tie them together and tow a load and survive? Yes you can. I did it on my Tundra just for ease of adjusting the bags together, but if you are going to go through all the effort you are I would do it right.

 

[stevezero]

I have my airlift kit plumbed separately, and have the schrader valves behind the gas tank door. I wouldnt use a T on a vehicle with a high center of gravity. Asking for too much trouble like scottryana explains. My bags are about 8 years old. I had to replace one just after I got the kit, it got a slice in it from a sharp burr on the rear spring. When you install your kit, run your fingers around the coils and look for sharp spots. sand em down, and youll be fine.