Installing air bags for load capacity and stability

[DrewsBrews]

Helper airbags give the ability to add rearend weight bearing capacity and stability to your car. They can be aired up to add several hundred lb of capacity, then aired down to ~5psi when not carying a load to maintain a more stock ride.

I previously installed some in a 1st gen Scion xB and towed up over half it's weight in a trailer. Loaded it up to the ceiling with bagged mulch. It was pretty awesome what it allowed that little car to do. The only stipulation is the car can't have rear struts.. IE shocks inside the springs on the rear.

I recently acquired an 04 Grand Cherokee as a spare vehicle. The air bags might not have been super necessary, but my trailer can have upwards of 300lb of tongue weight if I don't balance out the loading. That, along with more packed items loaded in the vehicle, can be a bit excessive for non-trucks. So I decided to add the Airlift kit. This kit set me back about $140 for the Jeep, but can get closer to $100 on kits for cars that accomodate a more simple install (IE less vehicle-specific parts needed).

Each kit is specific to each vehicle so there will be differences on included items and install. The xB I was able to squish down the airbags and install them without removing the springs (with some included pucks under the airbags). But the kit for the Jeep has a replacement insert for the bumpstop that wouldn't fit inbetween the coils so removing the spring was nessecary. Airlift I believe does have more generic kits available.. But it is on you to be sure it is installed correctly.

First jack up the car and add some jackstands. I like to put the rear wheels under the frame rails for a final line of defence if things go south. It may not be enough to save you though. I also keep the jack raised under a spot that can handle the full weight of the vehicle. But if you are doing this, it is up to you to determine what is safe.

Add some wheel chocks. I mean you've already got those for your trailer anyway right?

The kit:

Red air bags, black spacers, air line, valves and fittings/clamps, and some additional heat shielding due to close exhaust pipe proximity of the Jeep "WJ".

 

[DrewsBrews]

For the Jeep, the bump stops are inside the coils. These get removed so a replacement spacer/bumpstop can be added that has room for the air line connection to the airbag. This spacer doesn't fit between the coils so the coils must be removed. To facilitate that I unbolted one end of the swaybar link and shock.

I had new springs, but I imagine most will be reusing old springs. I suggest cleaning off your old springs. This will reduce grit trapped to rub through the airbag over time. Then squeeze the airbag flat by kneeling on it and add the cap back on the air line nipple so it remains flattened. This allows you to slip the air bag inside the coil. Remove the cap to allow the airbag to reinflate. They didn't self-inflate fully for me, so I partially slipped the airline on and blew in with my lungs.

Then install the airline on the airbag along with the little hose clamp and the spacer. Install the spring back in the vehicle.

 

[DrewsBrews]

I can put a jack under the rear axle to transfer the weight off the jack stands and back on the axle. This is what it looks like with the vehicle weight loading the spring back down.

Running the airlines will be specific to the vehicle. Generally it is a good idea to follow the brake hoses as they are engineered to handle the suspension articulation.

The airlift kits come with two schrader valves so you can run them separately. I ran them seperately on the xB to the rear side panels inside the interior. The kit also comes with a Tee so you can combine them to a single valve. This is what I did for the Jeep as I was concerned there wasn't enough airline included for two full runs. I ran it back to a single valve terminated at the bumper next to the hitch.

Dual vs Tee installs have their own plusses and minuses:
-Tee install means only one valve to air up and check the pressure. However, air can also transfer between the bags through the lines. So you get the benefit of leveling the vehicle, but there is less side to side stability benefit.
-Keeping them seperate gives maximum stability in turns and increased passive sway stability. Though, there are two valves that you must match up/adjust the pressure for the load.


The bags can be aired up to 35psi for a few hundred lb of added load capacity in the rear. I typically would pressurize to the specific load (IE just until the vehicle is level). When not under load keep ~5psi in them to prevent them from being pinched or excessively rubbed by the coil spring. Airbags are famous for their cushy ride, so 5psi realy does not add any harshness. Though you may notice the lightest whif of extra stiffness in the rear end. Which IMO tends to make the vehicle handle slightly better anyway.

If you are interested, I suggest looking up kit compatibility on their website (Air Lift Company). If one is available, check out the .pdf manual to get a beter idea of what the install requires for your specific vehicle.

I am not affiliated or in contact with Air Lift at all. This is a niche product that I don't think many folks have heard of. I'm just getting the word out for folks that might benefit from it.

 

[DrewsBrews]

The air line is nothing fancy, just a flexible vinyl hose. Slip a spring clamp over the line. Slide the line over the little barb/nipple on the airbag and the valve. I like to wet the hose end to make it a little easier to slide on. Then the spring clamp finishes it off.

 

[KCStudly]

An easy solution to the single fill port, but isolated spring pressures (to avoid "cross talk" and sway issues) would be to add a quarter turn push-to-connect ball valve in each leg of the Tee after the fill port. That way you could open both valves for simultaneous filling/venting (on level ground, of course), or isolate either side for adjusting either side individually.

 

[DrewsBrews]

An easy solution to the single fill port, but isolated spring pressures (to avoid "cross talk" and sway issues) would be to add a quarter turn push-to-connect ball valve in each leg of the Tee after the fill port. That way you could open both valves for simultaneous filling/venting (on level ground, of course), or isolate either side for adjusting either side individually.

That is a good idea!

 

[KCStudly]

Most of my professional career has involved fluid systems in one form or another. I guess you pick up a few things along the way.

 

[exminnesotaboy]

This was a great, super helpful write-up!

About 15 years ago, I installed an air bag kit on my 2001 Tacoma. Since I had leaf springs and not coil springs, the design was different than the write-up above, but works on the same principle. I don't inflate my bags often, but when I do, it really smooths out the ride and keeps me from blinding oncoming motorists with up-angled headlights from a heavy load - most often pulling my teardrop at night with a load of firewood in the truck bed.

It took a couple of hours to install, but I am slow and meticulous lol. I did purchase a replacement set of air line tubes/fittings to keep in the truck in case that I damaged a line. Of course, I've never had to replace a line set yet. There was some drilling and cutting of the old bump stops, but the kit had good directions and included everything needed for a straightforward install. I opted for the Firestone Ride-Rite brand as that is the brand that Tacoma enthusiasts often use on the truck forums. I am sure the AirLift brand would have equally as good

Due to the light rear weight of my truck, I always deflate my bags when there is no load, or it rides really rough. However, as mentioned above, I always keep a few pounds in them to eliminate pinch damage. Airbags take very little air, so a mini-compressor is plenty powerful enough to inflate them. I often wonder if I could inflate them with a bicycle pump, hmmmm.....

Pro tip: if you struggle to locate a good schrader valve mounting location and have a truck with an open/hollow rear bumper, you can mount your valves in the top two license plate bolt holes. This worked great for me allows very easy access.

 

[CanuckShooter]

I put airbags in my F-150 with an onboard compressor that I can control with a remote from the cab, 0 psi to 100 psi. I needed it when putting my atv in the back to stop the squat of the truck. With my 20 foot flat deck with homemade camper on the ball it's was really really necessary. Well worth the expense.