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  #1  
Old November 2nd, 2015, 01:52 PM
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John B.
1991 Defender 90, 200TDI
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Longer Air Bags

I've been running air bags inside the rear coils of the 90 for quite a few years. It has been my preferred option. It lets you keep a light spring while maintaining ride height when you load up the truck. It does not let you have variable ride height like an air spring, but has the advantage that if you have a puncture, you are not disabled.

I've been happy with the performance and ride, but there have been some niggily things that I've wanted to address for a few years. Airlift and Firestone both sell kits. They are both a bit short for a stock 90 as I assume they are setup for a Stock Disco, which runs lower from the factory. Originally, I bought the Airlift kit (61741). It uses a 9" air bag. I then bought the Firestone kit (4121), which has a 10" spring to see if it gave a taller setup. They were both designed for the same height with different spacers. I've lost track of what went with what, But "I think" that they work out to about an 11" ride height for the spring itself. Anyway, I wanted to be more around 12.5". I mixed and matched air bag spacers and put in a 1" seat spacer to get where I wanted to be. A little messy, but functional.

There were a couple of problems that I wanted to fix. The upper bag retainer is a polyurethane block and has been slowly getting destroyed by the spring seat, so something more robust needed to be made. The second problem was the Firestone bag leaking. They use a push connect tube fitting. It is fine when clean, but a bit of mud and dirt and eventually, it leaks slowly. You can fiddle and clean and get it to seal or refill the air every day. A bit of a PITA. The Airlift bags use a barbed fitting, so have less chance to leak.

It has bounced around in my little brain that I should check with Airlift and see if they make a longer bag which would allow me to get rid of all the spacers. I was looking at air springs and noticed that TruckSpring, http://www.truckspring.com/Search.as...=Air-Lift-1000 lists the bag sizes... Not only that, but they let you filter by size.... Seconds later, you see that Airlift makes a 12" bag at the same diameter. Kit 60818 with springs 60318 for 2009-2015 Dam Ram 1500s.

So I bought that kit and made up suitable upper and lower retainers and voila, new system.

Air Bags | Land Rover Modifications | Red90's Photos! | Red90.ca
- Airlift kit 60818 (for 2009-2015 Dodge Ram 1500). Spring part number 60318. 4.35 inches diameter by 12 inches long.
- Using with genuine spring packers, ANR2938, top and bottom, which are 3/8" high each.
- Springs are NRC4304, which are supposed to be 170 pounds per inch and 17" long. Mine measure closer to 16.5". Being shorter than they are supposed to be led to the desire for the packers.

The setup is designed so that empty with no air, the truck sits as the height I want normally. I can then maintain this height with up to around 1100 pounds of load by adding air.
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  #2  
Old November 2nd, 2015, 03:32 PM
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Scott T
1995 Defender 90 ST
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So John,

I'm curious, do you carry heavy loads alot, or tow trailers with heavy tongue weights? Seems like the rear is already pretty stiff (at least the NAS trucks) and can carry a relatively heavy load to begin with, so I was just curious..
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  #3  
Old November 2nd, 2015, 03:52 PM
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John B.
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I run anywhere from empty to multi week expeditions. So I probably get up the 1100 pound additional load on the extended trips with fuel. Without the airbags, I would drop over 3" with that much load. The "normal" route is to install aftermarket heavy springs and then you are tall and very stiff unloaded.

My rear suspension is not stiff. 170 lb/in springs. Stock is 225, so 75% of stock. The air bags add about 30 lb/in at minimum pressure and 75 at max pressure, So I get about 200 lb/in unloaded up to 245 at max.

I also have Koni shocks which have very little compression dampening on the rear shocks.
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  #4  
Old November 2nd, 2015, 04:16 PM
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John B.
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I also have the air system plumbed to allow me to cross link the bags. I do this off road to reduce the progressive nature of the bags. With the way it is setup, I can rest on the 1" extended bump stops in articulation when unloaded or loaded.
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  #5  
Old November 2nd, 2015, 04:16 PM
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Don Bunnell
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Very nice!

I agree with the thought process as it seems a stiff spring with a light load makes the rear end bounce a lot with our straight axle design. At least that seemed the case with my 110 before the rebuild that sat on HD rear springs.

I know I will have to change the rear springs in my 110 at some point and was thinking going taller/lighter rate. Might have to look into supplemental air too.

Thanks for the writeup
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  #6  
Old November 2nd, 2015, 04:34 PM
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Sonny
1993 NAS 110
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Thanks for the information! We currently have a set of the Airlifts on our 110, and they were a great addition for us! I'm not sure which model we have, but I'll keep your info for future purchases!

Where ours are super helpful is when we're running our Autohome roof tent on the truck...That's when we're running really heavy with a lot of camping gear and such and the Airlifts are perfect for keeping the rear from sagging! We're normally empty (just 2 dogs in the back) when running around, so they're super easy to lower the pressure and smooth the ride back down. I love the Airlifts!!
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  #7  
Old November 2nd, 2015, 05:00 PM
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Scott T
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Quote:
Originally Posted by Red90 View Post
I run anywhere from empty to multi week expeditions. So I probably get up the 1100 pound additional load on the extended trips with fuel. Without the airbags, I would drop over 3" with that much load. The "normal" route is to install aftermarket heavy springs and then you are tall and very stiff unloaded.

My rear suspension is not stiff. 170 lb/in springs. Stock is 225, so 75% of stock. The air bags add about 30 lb/in at minimum pressure and 75 at max pressure, So I get about 200 lb/in unloaded up to 245 at max.

I also have Koni shocks which have very little compression dampening on the rear shocks.
Hmmm, okay, was just curious. I run OME 759's in the rear which are around 260/300 progressive. Seems like the front end articulation is pretty lazy of the rear springs are too soft, no?

These were part of the old Safari Gard Stage III suspension. Unloaded, the butt sits a little high, but loaded for the weekend it sat nice and level. I never really weighed the load added, but wouldn't have thought it much more then 5-600 lbs max.

Anyway, just thoughts..
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  #8  
Old November 2nd, 2015, 05:17 PM
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John B.
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Quote:
Originally Posted by LRNAD90 View Post
Seems like the front end articulation is pretty lazy of the rear springs are too soft, no?
Articulation rates are quite balanced. I have a 91, which has the narrower radius arms and these articulate well until they run out of bushing travel. The later, wide radius arms especially when they have the three shell bushings are crap.

Front springs are 175 lb/in.

Old photo with stock springs, but the truck is very balanced in articulation.
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  #9  
Old November 2nd, 2015, 05:18 PM
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Charles Galpin
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Seems like a practical solution to the problem of varying loads. So are the bottoms retained? Hard to tell.
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  #10  
Old November 2nd, 2015, 05:24 PM
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John B.
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So are the bottoms retained? Hard to tell.
Yes. It is the stock retainer, that I bent up as I have the spring packer in there. There is a 1/2" plastic piece to provide a flat surface for the air bag. I used countersunk head bolts. The plastic piece came with the kit and was meant to be the upper bag support on the Dodge trucks.

When you buy the Airlift Land Rover specific kit, there is a piece they supply that goes over the stock retainer bolt heads, which could have been used instead.

This is a pic during the build. After that, painted the retainer and used stainless bolts.
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  #11  
Old November 2nd, 2015, 05:29 PM
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Charles Galpin
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I meant the bag. It's still not clear if the bag is retained in that bottom hole to the puck? It appears the bottom is retained but not the top? - just curious.
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  #12  
Old November 2nd, 2015, 05:34 PM
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John B.
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I meant the bag. It's still not clear if the bag is retained in that bottom hole to the puck? It appears the bottom is retained but not the top? - just curious.
The bags are never retained in any way. They inflate and fill the inside of the spring. The Airlift versions have a small ridge in the center which, I suppose is meant to keep them centered. The way it works in real life, they always stay in the center. When you go to full droop where the spring is longer than the bag, you get an even gap top and bottom from the bag.
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Old November 2nd, 2015, 05:38 PM
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Charles Galpin
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Thanks for the explanation.
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