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Thread: Air Shocks & Air Bags (2wd, but should also work on 4wd).

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    Air Shocks & Air Bags (2wd, but should also work on 4wd).

    As some of you know I put my van through severe service. I carry a heavy fixed load of around 3,000 lbs & I often tow a small covered utility trailer. I put air shocks on this 86 LE back in the 90's, but time and stress have taken their toll. Both shocks were leaking oil and would no longer hold air. Even when they did hold air I was asking a bit too much of them (inflated to 125 psi they couldn't quite lift it where I wanted it to ride). Then there's the question of stress on the shock mounts. The vans with coil springs have solid shock mounts, but it's still a lot of pressure in a small area. Here's a picture of my van I took yesterday (notice how low it sits in the back).


    So I've been looking for replacement air shocks but could find none that said they'd work on a van. I ended up taking measurements and based on that I finally found some that fit the bill. The ones I got are Gabriel 49203 Hijackers Air Shocks - 2 Pack.


    I'm not going to elaborate much on the shocks because they're pretty much a direct swap over. Being air shocks they will require running of air lines, but they come with instructions and it's pretty easy to figure out. The only "hiccup" with the shocks was the diameter of the "can" (at the very top) is a bit big & the mounting stud was too long. I compensated for that by simply using 2 of my old rubber mount bushings in place of the one between the shock and the body/frame of the van. With 2 bushings it made the stud slightly too short (had trouble getting the nut started), so I ground a little off the rubber bushings and that did the trick (sorry no pics).

    In addition to new shocks I decided to put air bags inside the coil springs. My research narrowed these down to 2 choices. I could use Firestone W237604112 Coil-Rite Kit or AIR LIFT 60812 1000 Series Rear Air Spring Kit. As an RV tech I install Firestone air suspension products and am familiar with them, so I chose the Firestone Coil-Rites.




    I didn't take pics of removing the springs and old shocks, but this is all straight forward and easy. 1st thing is to jack the van up in the back, then put jack stands under the frame (not the axle). I used the forward mounts of the lower control arms to support the van. With jack stands secure, I lower the rear axle until it's hanging on the shock absorbers. With the jack still under the differential, I remove the shocks, then drop the axle as far as it will go without stressing the rubber brake line. With the axle in this position the springs lift right out.

    In order for the air bags to fit this rubber stop needs to be removed. It's got a hole in the center and a 12 mm socket with extension will fit inside to remove the mounting bolt.


    To prevent things from becoming a big mess, I throw the springs and rubber isolators into my garage sink and remove the road grime. When clean I cut a short piece of 1/4" air line and shove it into the air bag.


    Next I take my Mitivac hand vacuum pump, slip the hose over the air line, and suck all the air out of the bag.


    This is required because the air bag is too big to easily slip down inside the spring.


    With all the air out the bag can be folded over and easily slipped inside.


    Once in position I lube the spring & bag up with Dawn dish soap and remove my vacuum pump (note: not all dish soap is the same. Some have harsh chemicals that may damage parts of the bag. Dawn is mild (no lye or ammonia), so this will not hurt anything. Lubrication is helpful as it will allow bag to slip into position as it fills with air and unfolds.


    Bag is slightly inflated to help it unfold completely.


    This is good. Bag is now positioned correctly with no folds or twists.


    I put my pump hose back over the bag inlet just to keep water out & rinse all the soap off the spring & bag.


    Next I trim the air hose. I'm going to use this little piece to help me lay-out the air hole in my spring mount.


    Next I put the lower insulator back on the spring mount.


    While carefully holding the spring in it's normal position, I look to see where the air line is touching the spring mount & make a mental note on location. (sorry, couldn't get this to show in picture).


    Spring is removed and location is marked.


    I drill a 3/16" pilot hole.


    Followed by a 1/2" hole.




    It's important there be no burs or sharp spots on this surface. I use a sanding disc on my die grinder to make it smooth. After the sanding disc I smooth it with Scotch-Brite disc.




    I apply some Rustoleum for protection.


    Air line is removed and plastic puck is set in place.




    Spring is installed and hole is inspected from under side to ensure it's lined up with air bag inlet.


    Air line for final assembly is inserted into air bag.


    Air shock is installed and air lines are plumbed. Since this van was already set up with air shocks, the 1/8" lines were already run. I decided to plumb the air bags into this same air line (less work). I put together a tee for each side that will share available air with the shocks & the bags. For the passenger side, the spare tire rack support is the ideal place to mount.




    All of the above steps are repeated on the driver's side. The driver's side is a bit more cluttered & there's the hot exhaust to consider. I choose to mount my tee on the panhard bar support.


    Vehicle is taken off of jack stands and air suspension is inflated to 30 Psi. Here is a view from underneath of an inflated air bag.


    And here's all the weight being carried by these.


    And here's my new ride height


    FYI, I looked under a couple of my 4wd vans and all suspension components appear to be identical to the 2wd (at least on the rear). I can't speak from experience, but I believe these same parts will also fit a 4wd van.

    Disclaimer: I am posting to show what I have done to my van. I am not advocating anybody else do this. Any time you work on or modify your vehicle you do so at your own risk.

    WARNING: The LSP & BV (Load Sensing Proportioning & Bypass Valve) relies on factory spring rates. By lifting a van in this manner you'll essentially be disabling the rear brakes. Since I carry a heavy fixed load, I was able to compensate for this by lifting my LSP & BV lever to it's maximum height & permanently fixing it there. For more information on the LSP & BV CLICK HERE.

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    Great thread! I think I'm going look in to the same kind of setup for my van.

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    Thanks. You won't regret it. My only regret is not doing this a long time ago. The van rides so much better now and I actually have suspension! I used to slam on my brakes for speed bumps or they'd launch me like a rocket. The air bags do a wonderful job absorbing bumps.........it's like riding on a cushion of air . Tim

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    Quote Originally Posted by timsrv View Post
    Thanks. You won't regret it. My only regret is not doing this a long time ago. The van rides so much better now and I actually have suspension! I used to slam on my brakes for speed bumps or they'd launch me like a rocket. The air bags do a wonderful job absorbing bumps.........it's like riding on a cushion of air . Tim

    this would be awesome on my 87 4wd! Does it give you any lift? Mine has spacers but they are getting squished out and the PO had them all zip tied on so they're basically just hanging there

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    Yes, it will give you lift, but the more air you put in, the stiffer it gets. Due to my suspension being overloaded, I needed the lift just to reclaim my normal ride height (my suspension was bottomed out). Overinflating will definitely lift beyond normal height, but your van will ride like a logging truck. If your van is overloaded (like mine) Inflating to normal ride height will give the best ride. Tim

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    Quote Originally Posted by timsrv View Post
    Yes, it will give you lift, but the more air you put in, the stiffer it gets. Due to my suspension being overloaded, I needed the lift just to reclaim my normal ride height (my suspension was bottomed out). Overinflating will definitely lift beyond normal height, but your van will ride like a logging truck. If your van is overloaded (like mine) Inflating to normal ride height will give the best ride. Tim

    hmmm thats kinda what i thought. so adding 2" of lift would stiffen it up a ton. looks like this setup would be more oriented to hauling heavy loads like you're doing. I think ill probably go with the aerostar spring lift mentioned in other posts and new tacoma bilstein shocks. that will give me additional travel off road as well and i won't have to worry about squashed spacers. thanks for the reply!

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    Hi, thanks for the detailed post! Any recommendations for rear suspension upgrades (still running factory original springs and shocks) on my 89 4WD Van? I read what you mentioned about the LSP and BV and my load weight varies from empty to heavy fairly often.

    Any suggestions or links to existing threads would be appreciated!

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    how are the air bags holding up? id be worried the coil springs would rub their way thru the rubber bags over time with dirt and grime...

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    Re: Air Shocks & Air Bags (2wd, but should also work on 4wd).

    After 4 years and 60k miles of extreme service they are still holding air (and the ride is still awesome). I check air pressure every 5k miles when I rotate my tires (about every 4 months) and they usually lose about 2 - 3 psi (this is normal for these). If your van is overloaded, this is one of the best mods.......probably not necessary if you're carrying normal loads. Tim

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