Ok, so I'm finally getting around to installing the Firestone air springs I was so horny about earlier this summer.

Yesterday I swapped ARB/M10 package from SWB RR to LWB RR, and of course the LWB started sagging in the nose.

I figured there's no time like the present, so went out and found the correct hardware today and started dissasembling suspension of LWB.

Luckily the original air springs had been removed and they were replaced with stock coil Disco springs, so not too bad on the removal.

The install of the air springs is a snap!

Initial driving tests are leading me to believe that this will be a sweet conversion. I am using the factory LR shocks (Woodhead I think), but will put in some RS9000's tomorrow if I can find them in town.

I only installed front springs for now. Rears will have to wait until I can get some more adapters machined.

Anyway, here are some pics of the first one installed on the passenger side of the truck only. I got the other one installed and plumbed in a single circuit tonight.

It's pressurized until the shock was fully extended. I think I still have a lot of room left on the air spring. More testing to follow......

The LWB to the right has the Rovertym 3 inch Heavy Duty springs for comparison.

Tires on both trucks are Dunlop Radial Rover R/T, 235/85/16's.

a sneak peek at the air spring...

looking nice mike looks like i'm the only one still up on the east coast guess that's what you do when you are on watch at 3 in the morn' can't wait to see the final product

-ben

Seems like a very interesting conversion. I have considered air suspension on ever one of my trucks at one time or another.

Mike,

What psi are you running it at?

Ali,

I think it was at about 45-47psi last night when I parked it.

I measured the ARB bumper, and the top of the flat part was 30 inches off the ground. This morning it was 29 3/4 inches. I think the springs must be settling, as I can't find any air leaks.

Got some Rancho's, so now I need to find somewhere to ramp this.

Maybe I'll just have to build my own ramp!

Sounds good. I'm curious to see how the bags behave when they're totally compressed; ie. in a wheel stuffage scenario. Also when the bag is totally deflated such that you're on the bumpstops, do their diameter increase dramatically? What's their diam while in normal inflation BTW? If you didn't have the shocks, how much farther do you think you can go? Is there a chance of the bag detaching itself at the bottom if you go too far?

Lots of questions!

Ali

Originally posted by alia176
Sounds good. I'm curious to see how the bags behave when they're totally compressed; ie. in a wheel stuffage scenario. Also when the bag is totally deflated such that you're on the bumpstops, do their diameter increase dramatically? What's their diam while in normal inflation BTW? If you didn't have the shocks, how much farther do you think you can go? Is there a chance of the bag detaching itself at the bottom if you go too far?

Lots of questions!

Ali

Wheel stuffage: There is an internal bumpstop that prevents the bag from totally collapsing on itself. I had to ride on the bumpstops from one side of the driveway to the other (to get to the Serious One, where the compressor is), in order to pump them up. I have a sneaking suspicion that they won't stuff as much as a coil spring will. I could be wrong.

Diameter doesn't increase dramatically, again, this was when the bag was deflated, not compressed from articulation.

If I don't have the shocks I can probably go another 5-6 inches, maybe only 4. I don't want to over extend the bag and get it all turned inside-out. I do plan to run check-straps to prevent that while off-roading as well as when I put it on a lift.

There is a retaining plate on the top of the spring that keeps it bolted to the factory frame perch, as well as a 1/2 inch bolt that passes through the axle plate where the spring normally mounts to. There is no way the spring can come unseated unless the bolts or plates failed. With checkstraps it should be a pretty stout system.

There's still much to learn from my end too, as I haven't had them on more than a day (and it was late last night). So, I haven't had much time to play yet.

The intent isn't to have a 'ramp-champ' or to challenge traditional coil springs. The intent is to have a fully manual air-spring replacement system to be able to load up the springs appropriately depending on loads carried and/or towed.

Looking good Mike .I think that with some adjustable rancho's you cant go wrong ,as the fine tuning would be great .Must be hard to decide which rig to take out ,what with all them Rovers .

Sorry ,but I cant help noticing that the only stains on the road seem to be where all the Rovers are .Reminds me a lot of my driveway .The stains ,not the amount of Rovers .

Luke .


*EDIT* you have email .

Looks good Mike,

I thought long and hard about air. However, I didn't want anything that an errant rock/limb/who knows what could bust a line for me just for giggles. What did you use for Plumbing? braided? Copper? Green Aluminum? I know you didn't just use plain old pvc. NOT YOU! :flipoff2:

j

Well, here's where I surprized you I guess.

The air fittings exit the top of the air spring and in the front, the plumbing is entirely inside the engine bay.

In the rear springs, the lines will still exit the top of the spring, run along the frame rail to the air tank/manifold set-up.

If a limb/whatever punctures that hose, it'd have to hit a moving target less than 1/4 inch in diameter square on really hard. If you had a puncture you could always cut the line cleanly and install a female/female fitting and you'd be back in business.

I have worked with the hard lines and real brass fittings for so long, I just got tired of the cost (super expensive) and hassle tracking down leaks. The most expensive fitting I've purchase so far with the PVC has been the bulkhead fitting ($5), and the line is like .30cents a foot. Compare that to other fittings/line and you'll start to see why I'm using this as a testbed for the PVC as well as the air springs.

After 3 days, no leaks so far. Wish I could say as much for the propane hoses I just completed. Something in my trailer cooking system is leaking slowly, so I need to go after it with the soapy water sometime soon.

Thanks for the compliments! I hope to have it out wheeling next week for real.

Michael,

What is the spec on the airbags. If its the AB9011 then I got the spec sheet on it which might be of some help to Ali. It gives a graph of the load supported for different constant pressures (20 to 120psi) at varying heights.

If its some other bag I can probably get the data sheet for them also it was that I was looking at using this bag myself.

Its really interesting the way they conture the cone at the bottom to control the spring rates.

Sam

EDIT : got some progress on the bush front. We got the mold off the guy and are going to get some inserts machined up ourselves to produce the new style of bushes. At least this way we got control of the thing and can get everything happening instead of him doing it in his spare time (of which it seems he has very little) :D

Very cool stuff...

I was thinking of doing the same thing. I am putting an ambulance body (Ex Mod) on my 109 and the idea of having all that weight on leaf springs is a little worrying. I'm thinking of building a three link (with a new rear axle), but I didn't want to use coils as I'd like to be able to raise and lower the spring rates for driving/offroad.

A few questions here. I'm relatively new to this type of spring.

Firstly, does an increase in spring rate mean a massive increase in height? I wouldn't want the rear rising too much when I stiffen it up for on-road. Likewise, I don't want it too stiff for off-road.

How thick is the rubber? Is it liable to be punctured by a branch?

How much are these things?

thanks for the info, keep up the imagineering, very interesting.

J-L

HandBuilt,

Thanks.

The air-springs retail for about $137US.

I consider the construction of the air spring to be roughly that of the side-wall of a tire, both in terms of actual construction and relative toughness.

Spring rate on an air spring is something that I'm figureing out as I go along.

I think that you need to pursue it in four stages.

1. Decide on the design parameters, select air spring accordingly.

2. Decide on desired spring rate through experimentation of air pressure in air spring.

3. Determine ride height desired. Adjust mounting of air spring relative to ride height and spring rate.

4. Use it, re-evaluate.

I think I'm in between 2 and 4 somewhere. The ride height will increase as pressure increases. Believe me, you can jack it up way past where you really want to be, both in terms of height and stiffness.

I think I need to learn some physics and some applied engineering. I have a manual published by Firestone about all the physics and spring rate stuff, but I'm too stupid to figure it out. Duh! :confused: :confused:

If you increase the pressure you increase the ride height and decrease the springe rate cause there is a greater volume of air in the spring.

If you decrease the pressure and lower the ride height you increase the spring rate.

Sam

So you are saying Strange Rover, that if my airbag has 1psi (but not sitting on the bumpstop), it has a higher spring rate than if it has 1000 psi (with a static non ballooning wall)? Not sure I understand this, if that is the case. I checked on several airbag sites (Airlift and such), and they do not explicitly state that an increase in air pressure increases spring rate, but they imply it pretty frequently. Hmmmm.

Billster (by no means an expert with airbags on a truck, only airbags in humans)

ps. Decreasing the air pressure of your tires effectively decreases the "spring rate" of your suspension (rides smoother). Increasing the air pressure, increases ride stiffness (spring rate).

I think strange got it backwards. The rate INCREASES with more air. It's a volume thing. More pressure at a given volume equals less flexibility via the fact that you are actually moving the "mass" of the air. Therefore the rubber baggy thingy won't move as easily. (will move the same distance it would before, just takes more force).

Serious one is right on target with the mounting height of the bag. (as usual). Find the maximum compression height for the bag, and mount it there. This way you have the most flexibility in lift and load carrying ability. Simple thoughts (and Mike, keep me honest) the larger the diameter given a static height on the cylinder will result in a softer spring at all pressures?

j

Me again.

Yeah, Strange did get it backwards. That's ok though, considering all the toilets flush counter-clockwise in Australia.....:flipoff2:

The 'softness' of the spring, i.e. having the spring feel 'soft', is towards the under inflated end of the spectrum. Bill was thinking correctly using the tire analogy. Less pressure = soft spring. Lots of pressure = hard spring. Think of an air mattress, that'll put it into terms you know and have felt before.

What I *really* need is a jig that is adjustable so that I can put various air springs into it, inflate it without it going flinging all over the shop (happened once already!) and then have either the lower or upper portion of the jig be mounted on a hydraulic ram so that I can move it up and down. Of course the jig would have a pressure guage or a resistance guage, or some sort of guage to give me real time data as to what the spring is doing.

Short of that I'm going to have to find a ramp and just play with air pressures and ride heights.

Where the truck sits now is perfect as far as ride height goes. There is some minor rubbing of the air spring against the frame bracket, but nothing that I'm worried about. It actually doesn't rub, but just rests/presses against the frame mount. In the Firestone catalog it suggests 1/2 to 1 inch of clearance all the way around the air spring.

I consider the pressures and force of the spring pressing against the frame to be no worse than the rolling lobe (air bladder) pressing against the piston (lower plate tower thingie). Also, there is no movement between the frame and air bladder to cause any rubbing/binding/pinching/friction whatever.

I have found a Goodyear air spring that has a smaller outer diameter, with only 2 inches less extended height that I am considering looking at. It is significantly smaller which would reduce rubbing, and the lesser extended height of the spring might not be a bad thing.

Considering that I am looking at varying the mounting height of the spring anyway. The mounting points are similar, and my adapter plates would still work, just have to have some of the holes moved to different positions. A cinch with the CNC program.

I'm to the point where I would like to have a 'softer' ride, but keep or even increase the ride height.

Billster and I spoke on the phone last night for a bit and basically his thoughts confirmed what I had already been thinking. Mount the bag higher. I can do this either at the top end where the adapter plates are machined, make them taller, or at the bottom end where the spring attatches to the axle. I have a plate at the bottom that could be extended very easily.

Still no leaks after, what, 3 days?

Still haven't gotten the Rancho's on yet. Hopefully they'll tame down the excessive rebound I'm getting. I described to Bill the way that the springs feel as somewhere between an OME MD and HD spring right now.

I'm not sure I can answer RedRangie's question accurately. Could you please repeat the question?

Thanks for everyone's input and ideas. It's nice to know I have my expert panel working in all areas of the world at all times of the day/night!

Wish I had some help yesterday when I dropped the pan on the LWB!!! YUCK!!!! :flipoff2:

its looking good mike! lets see some more pics with the springs mounted all the way around! what are you planning in regards to solenoind and proportioning valves? compressor? I know your not gonna have a belt driven one on the rover v8.;)

First off,

I did what all fawkin newbies should do and searched "air spring". Came up with a lot of info.

Serious One, I didn't realise that you were planning on going air spring for your crew cab. Different budgets, but I believe we are trying to get to the same beast, you and I. I'm building the 109 into an expedition type camping rig, something that I can take anywhere and be comfortable in, and still take it off-road. Something i can sleep in at the hill when I'm snowboarding, or that I can pile 10 mountain bikes in and go downhilling, or live out of it for a week. Off-road is a priority, but not the only thing.

Your rear box looks like either an equipment hauler or a camper, so the load dynamics and the inherent variability of load (empty to overloaded) make this sype of adjustable suspension so alluring. I'm planning on staying with a leaf sprung front end for now, as it works beautifully and it's very solid and hard to break, but the rear is just a mess. I've got spring swap in a major way, and if I put in some extra leaves, I end up with a CG that is scary high.

So, I'm looking at a 3 link similar to a rover coiler, but with a long arm setup. What I really don't like about the rover setup is that the radius arms are very short, and they make the vehicle "flex steer" off-road. I'd probably be running very long radius arms and top "A" arm, to minimise this problem. I'm not looking for horrendous flex, just a solid suspension design that will hold up, and carry a lot of load. I've got the wheelbase, so why not use it?

I think you are right in saying that the ride height would be best set by trial and error. One idea I have been toying with is mounting the top of the air spring to a crank, supported by a shaft spanning the side-to side of the chassis. Hook this crank to another air spring, which would control ride height. By rotating the shaft hooked to the cranks (one each side) You could almost infinitely adjust spring rate and ride height independently.

I think this is a poor description, think of a swaybar with the ends hooked to the top of the spring. Then, find a way to turn the swaybar so the top of the springs on both sides go down or up depending on where you want to set it. Put a large crank arm welded to the center of the swaybar, pointing straight down. Hook that to a fat air spring, or perhaps a hydraulic cylinder, with other end tied to the chassis. You would set your spring rate, then your ride height. I could cruise down the highway with lower than stock ride height ambulance, tires right stuffed into the fenders, for better handling and road manners, and have super supple spring rate and tons of body clearance for off-road.

I think I'm onto something here. Ditch the fixed top mounts, make the top mount of the air spring look like a big rod end. Build a bellcrank out of two pieces of CNC'd heavy plate, affix to large piece of tube (strong torsionally) and support on two big ass pillow block bearings. Another set of bellcranks (or just one) under the truck between the framerails, hook these to whatever you want, I'd probably just use two big bolts for now, and tighten or loosen to adjust. The ideal would be another air spring, but it might compress when hitting a bump, so it would give you tons of travel, but perhaps not as stiff a ride as you would want on road. However, you wouldn't get any body roll. Sweet setup for a top heavy vehicle that still needs some flex off-road.

Costs? Wouldn't be that bad. You would torch the mounts off the chassis, use the rover mounts on the axle, and the rest would be pretty straightforward to fabricate. You would need three airbags, or perhaps two and another means of adjusting ride height, a screw/thread type setup. The center airbag could be anything as it's size and travel aren't a concern. All it has to do is be able to hold the load, and with the bellcrank ratios, everything could be adjusted.

Hmm. If only I could afford airbags. Damn College tuition.

J-L

Air compressor? I thought I'd mess with the one that's on it already, see if I can't remove all of the ECU crap and just put a switch on it.

Solenoids? Don't need no stinkin' solenoids. I'm going all pneumatic man. I don't want to make this more complex than it needs to be. Speaking of getting rid of solenoids, watch what Warn does with the thermometric winch next. ;) You didn't hear it from me!

I have a 2-way guage with two switches plumbed into the guage (Firestone guage BTW), one for each end. I'll plumb into the 2.5 gal. tank that the LWB comes with for the factory air, and put lines from the tank to the switches to the bags. I'll also run lines to the lockers from that tank.

If the compressor proves to be unworthy, I'll probably do a quick air setup. I have liked Ed Sanman's in the past. I know he's gone to a heavier industrial compressor now, but IMO it's a little overkill (plus I need to quit spending money on trucks).

So, there you go. Pics of it fully air-sprung will take a while. I am still debating on the adapter height and even if I want to try these other air springs.

HandBuilt, I'll let you mess with the adjustable air spring mount. I need to keep it simple. Sounds intriguing though!

JL, what youre describing is a cantilever setup that is common on a lot of air sprung heavy dump trailers. check one out sometime, they are quite cool. it allows you to increase the spring rate without increasing the ride height and vice versa. very clever.

Originally posted by Strange Rover
If you increase the pressure you increase the ride height and decrease the springe rate cause there is a greater volume of air in the spring.

If you decrease the pressure and lower the ride height you increase the spring rate.

Sam

Havent got much time but I will explain some more.

The weight on the airbag is constant. So that if you increase the air pressure all you are doing is increasing the ride height (and maintaining a constant load on the bag). So now you are supporting the same load on a much taller airbag (and a taller airbag is much softer)


Now lets say the air bag is 10in tall supporting 1000lb. If you double the load to 2000lb then to support the load you must double the pressure so the airbag will compress to half its heigth (this is assuming a closed system and no more air is pumped into the bag (just like running over a bump)) So now the bag is at 5in heigh and supporting an extra 1000lb so the spring rate is 1000lb/5in = 200lb/in

Lets say you blue the bag up so that the height is 100in tall (being stuipid here) and supporting the 1000lb. Double the load and it compresses down to 50in tall (to get the doubling in pressure) so now the rate is 1000lb/50in = 20lb/in


The shape of the cone at the bottom does change things but it makes it even more so. When the ride height is low its very stiff and when the height is tall is very soft.

Gotta go.

Sam

Sam,

Maybe we should define 'spring rate' before we start comparing coil springs to air springs.

I'm going to dig up my Firestone tech book now....

Michael thought you might find this interesting....It is of Jason Paule's vehicle taken at the supercrawl.

Way

Way,

That's the setup the Sniper uses on the rear suspension too.

It's funny, that is basically the first way I was going to have an adjustable load bearing rear suspension.

Timm and I looked and looked and basically decided that in order to make it work special brackets to adapt to the a-arm would have to be made, and since we were making brackets anyway, why not just go for the fully adjustable air springs in place of coils.

I'm not sure that my way is any better/easier than the way you have illustrated the rock-crawler is using. It could definitely be adapted to a rear a-arm, just doing it would be the fun part (almost as fun probably as what I'm doing).

Additionally, we felt that if I came up with adapters, mounting plates etc...that replacement air springs could be designed to fit the front springs as well as the rear in (and this is the kicker) *any* coil sprung LR. Rather than just doing a one-off, there is potential for this to be marketed and sold in the future to a wide variety of LR's, not just for the rear a-arm.

Like I said, who knows which way would have been better in the long run. I can't predict the future and I certainly can't change the past. I've rolled my dice, now I'm waiting for them to stop.

Thanks for the pic though! (I'm flattered you're thinking of me.....)

5 days....no leaks.....no sagging.....

Front view with air spring completely extending Rancho 9012.

side view of same

I think that's a 9014. 9012 is eye to eye kiddo.

Oh yeah, thanks dad. :)

No wonder the guy at the counter looks at me weird when I ask for that stud to stud 9012.

Mike,

That shock is sure extended. At this stage, how's your brake line? I'm assuming that you don't have plans on driving at this height?

Hey Ali,

The brake lines actually weren't very close to being fully extended. I was surprized. My heart jumped when I saw a drip on the driveway, but was relieved that it was only windsheild washer fluid.

If you drove around like that you'd have a wildly stiff truck that would probably pick up the axle off of the ground when you hit the smallest of bumps.

After driving it around for a few days I'm starting to think that maybe a smaller air spring might be better. I think that the load rating for the spring I have in there is just so high that when it's pressurized enough to lift up the truck it's just really stiff.

I'm going to get another set of air springs and install them. These ones that are in my LWB right now will be perfect on the rear of the crewcab. I think I'm going to go to CA and bring it back to Vegas next weekend right before the SEMA show. Some friends from WARN and ARB want to see it, even if it's not done.

I'm actually kind of swaying towards this scenario with regards to the air suspension:

Keep coil springs in front, Rovertym for sure, probably the 3 inch medium duty lift will be fine for most if not all situations. Install air springs in the rear only for load adjustibility.

The stiff air spring really kind of gives you a jolt when hitting bumps. It's as stiff as OME HD springs that are *brand new*, so it's pretty stiff.

Anyway, I'll get some other air springs and see how they behave. More to come....