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Discussion Starter #1 (Edited)
I have been thinking about the possibility of replacing the rear coil springs with air bags. ie retrofitting the coil buckets to mount an airbag and running an on-board compressor. Has this been done?

Here is what I have come up with for Pros and Cons;

Pros;
-adjustable ride height with or without a load
-smoother ride quality
-assist to level out vehicle on side hill (with option to control bags independently)
-and the ability to compete in impromptu stoplight low rider competitions. (sweet) lol

Cons;
-overall cost compared to cheap coil springs
-durability with stretching/compressing
-weight increase if not already carrying a compressor

other considerations;
Is there an airbag that can have the desired amount of travel available?

Need to increase shock valving to help control axle at low bag PSI?

Would need to defiantly run limit straps to not over extend air bag.

Upgrade bump stops- the bump stop in the middle of the coil will be eliminated leaving only the ones on the bottom of the frame rail. Add additional poly bumps or air bumps? Re-use factory inner coil bump stops next to air bag?

Any comments on this idea are appreciated...if this is already in place on someones FJ, how do you like it?
 

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A couple of years ago there was a good story in Toyota Trails mag about doing this to an FZJ-80. Appication in rear would be close to what your planning. I have done a hybred version of your plan by installing air bags inside OME lifted coil springs. A full report is posted here somwhere.

About the only worry I would have with your plan is loss of an airbag or air line could leave you stranded. I suppose you could drive out slowly with axle on the frame. I prefer my set-up as "springs don't leak".

Alan
 

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A couple of years ago there was a good story in Toyota Trails mag about doing this to an FZJ-80. Appication in rear would be close to what your planning. I have done a hybred version of your plan by installing air bags inside OME lifted coil springs. A full report is posted here somwhere.

About the only worry I would have with your plan is loss of an airbag or air line could leave you stranded. I suppose you could drive out slowly with axle on the frame. I prefer my set-up as "springs don't leak".

Alan
What Alan says is right on the mark. If the air bag goes you still have a spring.

That is a big factor between picking air shocks or coil overs as well.
 

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Discussion Starter #4
yes, the fact that an air bag or air line could fail is obviously much higher vs a spring, but wouldnt the sweet air ride be worth it?

If you just put a helper bag inside of the coil then one could only make the ride stiffer then the spring rate of the coil.

Anyone else want the rear to ride much softer at times (with no load or on the rocks) but also have the ability to stiffen it up (in the whoops or with a trailer)?

Maybe the answer would be to just run a very low spring rate coil and an airbag inside.
 

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I bought a pair of OEM Land Cruiser 120/Lexus GX470 rear air springs, part no: 48080-35011 and 48090-35011.

Because FJ shares the frame with 120-serie, there are mounting points already for air springs at rear. So these would fit directly without modifications, except the lower spring plate which have to modify for the air spring.

I have planned to install a compressor and air tank. Simple system with up-down valve on the dash, maybe some release valve too which connect the bags together (for off-road use).

This is how they look:






Min. lenght is about 12 cm, neutral seems to be about 25 cm (like the original steel spring), max. is about 37 cm but I am not sure is it safe to lift it as high.
 

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Air bags have been done before on rock crawlers and while they sound good in theory they are more a PITA then they're worth. Some guys have done the manual valves to control their ride height while others use an automated system with different lift heights depending on the situation.

If you're really wanting to go with air bags look at the semi truck ones, they are overbuilt and can handle an extreme amount of stretch.

This is not the greatest picture but a local guy named W has been running air bags for years and he doesn't use limit straps.
http://api.ning.com/files/Umgs4VeHT...2M1-0J7ajxL878ds9vlnyTsqB9NIc0hwBiTO/0_03.jpg
 

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If adjusting ride firmness is one of your main drivers you could always get some soft springs and put airbags in them, so the suspension would firm up when you want it to.

But seeing the Toyota/Lexus airbags that FinnJ posted installed on an FJ would be awesome!
 

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Good question but this guy's last login was "Last Activity: 03-25-2013 08:43 PM" So it might take you a bit to get a reply. Here's hoping for a quick response though :bigthumb:
Where you found that? :) I have been signed in constantly, reading the forum at least every week if not daily.

But yes, the rear suspension is worked very well about 8 months/10 tmls. You can see them in my buildup-story (link in my signature).
 
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