1st Gen Custom Rear Airbags

So Ive been running this setup for about 4yrs now and it has been great so I figured it was about time to share it incase it can give someone else some inspiration/ideas.

How it began:
This truck is a '99 and the OEM leaf springs went flat long ago. About 3 years prior to adding airbags, I replaced the OEM springs with General Spring HD springs. They too went flat after about 2 years. Not wanting to constantly be replacing springs, or spend a fortune on specialty ones, I began looking at airbags. My main concern with airbag kits available, is...well...they just look weak and poorly designed for the loads that can be going through them, so I decided to make my own.

The Design:
The frame brackets are all 1/4in flat bar that has been bent to follow the contour of the frame and only attaches with 2 bolts, 1 in the bumpstop, and 1 in the lower flange of the frame just aft. This aft bolt also attaches a welded angle that is inside the frame just to prevent that flange from ever getting rolled under high load.
The axle mount also uses 1/4in flat with some welded 1/2in flat bars so the cradle will clear the u-bolts. I also used a daystar cradle here which simplified the attachment (one center bolt tapped into one of the 1/2in flats).
With the bags mounted in this location, I was able to align them pretty well with the axle, the bump stops (my thinking was this is a reinforced area of the frame already designed for loading), and pretty close to the center of the frame web (to minimize any torque applied to the frame).

Enough text, now some pictures (please excuse the dirt):







Here you can see the aft bolt and the angle reinforcement inside the frame (also didn't know about it rubbing a hole in my airline...need to fix that...):


Passenger side also got a simple heat shield for the exhaust:








Couple last notes:
All bends were made with a homemade finger press brake and a Harbor Freight 20T press
Usually run the bags at 12psi to get a good ride height and ensure they can't get pinched
Inflated with Schrader valves mounted in the lower license plate holes

Well hopefully somebody enjoyed all this and maybe it'll inspire someone to do something else cool. Let me know if there are any questions and Ill try to answer what I can (although Im not on here too much).

 

Just what pray tell are you carrying in the bed that wears your HD springs out in 2 years?

 

Im hoping I got a defective set because it sure didn't take much. Never got to tow with the springs but I think the trip that did them in was when I drove across the country for a summer internship. I had a duffle of clothes, a cooler, 5gal water jug, box of cooking stuff, box of personal stuff, and my camping/climbing gear. I picked up the camper shell that summer too so in total maybe 500-600lbs in the bed? I was consistently hitting the bump stops the entire drive home and decided I needed a fix.

 

Yeah, with the HD springs that should be no problem at all. I never really hit the bumpstops with 2 motorcycles in the bed of my doublecab.

How old are your 5100's? Looks like at least one of them leaks. That'll have a significant impact on the ride, too.

 

Yeah I thought they may be just the thing, if only they had kept their arch. After going both routes, for the price, I think I will always just do airbags in the future. Too easy to adjust the ride height depending on the load and a replacement bag doesn't cost nearly as much as new springs if it ever comes to that.

The shocks were replaced about the same time as the springs. I think they may have bottomed out a few times when the springs went flat which certainly didn't do them any favors. (I don't think 5100s will bottom out but I foolishly went with 5125s thinking the HD springs would ride a little higher). They are still damping well though and by looking at the dirt on the piston, they haven't bottomed out in a long time.

 

Your bumpstops should prevent bottoming out no matter how flat your springs are. With the bags effectively replacing the bumpstop, you want to be sure it still can't bottom out the shocks to prevent that from happening in the future.

I definitely like bags. I put some on my 4Runner to take out a bit of the squat when I'm towing my travel trailer.

 

For sure, air bags are nice. Ive been keeping an eye on the shock travel but it really doesn't take much air in the bags for them to function as bump stops.

 

Did you have to drill holes for any of the mounts?

 

2x holes per side: 1/2in through the front side of the bump stop and then a 5/16 (I think it was) through the bottom flange of the frame ~6in further back.

 

This is a really sweet set up. Its uncanny how similar my experience has been to yours lol. My General Spring HD's are also sagging after only 2 years (its nearly on the dot). I also have about 500ish lbs in the back almost all the time including the topper. I did however tow a 6x12 trailer twice this past summer that was fairly loaded quite a ways heading out to my internship and back as well. I think I'll be doing something similar with air bags, because I don't really want to buy new leafs again. Did you replace the sagging leafs after adding the airbags?

 

Sorry, been away for awhile.
Still rocking the "HD" leaf springs. Bushings were shot on the old ones so I kept the "HD" ones installed.

 

I added those to my 98. I have OME Dakars with the extra leaf. The leaf springs are made for off-roading and not necessarily carrying a heavy load. The bags are great for carry ing stuff. Cement, dirt etc. I also haul a motorcycle on a hitch carrier and with 7 psi in the bags it rides perfect.

 

I ended up buying new leafs and shocks since they were both gone. Airbags are now on as well and it definitely works well.

Good to hear about the motorcycle carrier. I've got one too and hadnt tried it yet, looking forward to it.

 

great write up. I've been thinking of doing something like this and I appreciate you posting. Do you remember what brand of airbags and/or a part number?
thanks again. I know this is an older thread but I hope you see it.

 

Sorry for the late reply but I went back through my old receipts and confirmed I used Firestone 6781 airbags. These are the same bags that they include in their 2304 Kit made for 1st gens

 

What brand are the air bags? and do you have an onboard compressor?

 

thats sick!

 

I do have a compressor but not permanently wired or plumbed, just mounted. Most of the time I top them off with shop air. For how infrequent they need it, its often not worth using the onboard compressor.

Ive heard of people just carrying a bike/hand pump and as long as it has a good valve that you can release without loosing pressure in the bag thats really all you need.

 

Nice work, looks really good and solid.