Defender Air Suspension

Kgh

Let’s go already!
At Abenteur und Allrad show, I made an offhand remark about LR4 air suspension...

Lo and behold I recieved a quick Nakatanenga demo of the 110 air suspension they carry. Super cool.

Too pricey for me, anyone know how it rides?
 

SteveMfr

Supporting Sponsor
I can't say anything about the ride of the VB air suspension - the ride is very dependent on the design of the air springs and these seem to be proprietary in this system.

I did meet a Swiss guy a number of years ago who had converted his D90 to air. He used OEM LR RRClassic air springs and built a manual controller, etc himself. If you were to go this route using Arnott air springs and one of the many manual controller kits available for air spring conversions, you could purchase all necessary parts for just north of $1500 or less than half the Nakatanenga price for the VB kit. The ride would, of course, be very RRC/P38 like.
 

DividingCreek

Explorer
Perhaps its my fading memory but I do not remember my air suspension cars favorably.

Certainly not enough to convert to air suspension.
I have worked with defenders that had air bags inside the coils but never a full air suspension.
While its cool intricate technology and neat the engineer types take the time to come up with these packages,
the idea seems to kind of fly in the face of the simplistic reliability that was the defender hallmark,
if you will never drive off pavement or heavily load your truck maybe it makes sense.
I guess I have become a curmudgeon.
 

Kgh

Let’s go already!
Perhaps its my fading memory but I do not remember my air suspension cars favorably.

Certainly not enough to convert to air suspension.
I have worked with defenders that had air bags inside the coils but never a full air suspension.
While its cool intricate technology and neat the engineer types take the time to come up with these packages,
the idea seems to kind of fly in the face of the simplistic reliability that was the defender hallmark,
if you will never drive off pavement or heavily load your truck maybe it makes sense.
I guess I have become a curmudgeon.

It does seem like a pretty cool system. That said, I am not about to drop 5K on it.

Simplistic Defender tech probably went away with the 300TDi, the Puma's are a bit electronically centered.

I am just posting up things I am seeing here in EU. There are so many options, just picking one something is tough.
 

spikemd

Explorer
Air suspension on the rovers is awesome from a road driving experience and occasional offroading. Instant lift when needed, keeps the body steady, compliant and great for towing. But if you are considering any serious offroading or overlanding, don't do it. Its another complex system that can go wrong and leave you stranded. I loved the EAS (air suspension) on my P38 and kept it up for a few years until my buddy, with brand new Arnott Gen3 springs blew out an air spring in Death Valley and had to limp home on bump stops for 400 miles. I ripped out the system the following month and never looked back.

The newer systems on the LR3/4 and Range Rovers are more robust, but I have also seen punctured air lines leave an LR4 stranded and flatbedded home 300 miles. Last month in Baja, an LR3 had a suspension fault and dropped to bump stops. We had to manually jack the car up to reset the EAS computer as it was out of the tolerances of the height sensors. Thankfully, it was a temporary issue, but if your tires are too large and you drop to bump stops, you may not be able to roll. Never a good situation.
 

SteveMfr

Supporting Sponsor
I don't know if I see the EAS, especially the modern LR EAS as a serious drawback to overlanding or even general offroading. There are definitely applications where a switch to coils might make sense. But as you note, the RRC/P38 EAS really isn't comparable to the later EAS systems, and later systems are generally so robust that there would need to be a serious additional reason for a coil swap.

Overlanding, in particular, generally requires long stretches of tarmac driving in addition to off road. This is exactly where the EAS shines. But if you are going anywhere seriously remote, you need to be prepared with some sort of diagnostic system if you are in a modern LR. Not just for the EAS either. There are a hundreds of things that can go wrong and leave you stranded. A diagnostic system is just as much an essential part of a toolbox for a modern Land Rover as a screwdriver or a hammer. With an adequate diagnostic system, you can take care of "out of range" faults, and pump an air suspension up manually to drive out of a situation if there is no other alternative.

The only 2 situations that are imaginable that can not be quickly remedied are a catastrophic electrical failure or a catastrophic mechanical failure. We have never seen or heard of a complete, catastrophic electrical failure (and we spend quite a bit of time on various forums all over the world as well as with our support for over 3000 IIDTools now in service), though I imagine sinking a LR in 5 feet of water for a while could do the trick. But in that case you will likely have more to worry about than the EAS. And we do hear of catastrophic mechanical failures such as ruptured air bags or air lines, but it is nearly always a case of inadequate maintenance combined with an extreme situation that causes the failure. Air bags need to be replaced at regular intervals (5-7 years) or you can wait for a failure as most do. But if I were traveling to Africa or somewhere remote, I'd replace the air bags proactively. Heavy equipment uses air suspension and the equipment is relied upon to make money. If it were that unreliable, they'd all be running some other type of suspension. I'd like to hear more about the LR4 with the punctured air lines...

And if you have tires on the car that are so large that the bottoming to the bump stops causes the tires to eat the car (without spacing the bump stops or similar), then you did not modify the vehicle properly...
 

Cupboard

New member
The air suspension in things like Land Rovers always seems to work upside down to me.

Makes sense in a lorry where you have massively variable loads, you can change the spring rate on the fly by adding a bit more air. On something like a Disco where you have relatively steady load (empty to full is only about a 1/4 increase) but want variable height for off roading, they're backwards. Off road you want long travel, soft suspension. On road you want firmer, shorter travel suspension. On a Disco, off road you increase the pressure in the air bags to give it a lift, and to my mind that will make the suspension firmer and less compliant. On road, you let the air out which will make it softer and more wallow-y.

Adjustable height suspension is nice for an off road vehicle and there's the advantage of being able to fit it in to garages more easily, but with solid axles you're not going to get any more ground clearance. I can see the attraction of a variable spring rate so it sits level and handles well when you load it up, and is still comfy when it's unladen. It just seems like a lot of complexity and expense for something that is effectively just a variable rate spring that's actually set up wrong for off road use. If you don't have the variation in payload, then a correctly set up coil spring should (I think) behave better than an equivalent air bag.

You could have a setup that primarily uses coils but reverse-biases them with air, so when you want to lower it you're preloading the springs and tricking them in to compressing prematurely. That might work, but yet more complexity.
 

Kgh

Let’s go already!
It is an interesting concept. With what I am seeing in Europe, a Puma defender with an AluCab pop-top, full Hesch interior cabinetry,mfridge/freezer, onboard H20, extended fuel tanks, etc etc one wonder what a fully laden 110 reads on the scales. I should have asked some of the people and A&A show.

I fully agree with Steve on the diagnostics piece. My 2.2L is probably not as complex as my LR4, electronically speaking, but it is alot more so than the Defenders we see in the US.

I also agree with prev comments that complexity is not a good thing, unless it is reliable. These systems are being used in 1,000s of caravans and other applications.

As I stated, I am not going to drop that kind of money on an air suspension. But I would relish the opportunity to ride/drive in such a setup.
 

SteveMfr

Supporting Sponsor
The air suspension in things like Land Rovers always seems to work upside down to me.

Makes sense in a lorry where you have massively variable loads, you can change the spring rate on the fly by adding a bit more air. On something like a Disco where you have relatively steady load (empty to full is only about a 1/4 increase) but want variable height for off roading, they're backwards. Off road you want long travel, soft suspension. On road you want firmer, shorter travel suspension. On a Disco, off road you increase the pressure in the air bags to give it a lift, and to my mind that will make the suspension firmer and less compliant. On road, you let the air out which will make it softer and more wallow-y.
No. This is actually a very common misconception with air springs. Lifting a certain weight requires a certain pressure. If you do not change the weight, the pressure required to lift that weight will be the same at access height, standard-, and off-road heights. The volume of air in the air bags changes. And yes, the air you are pumping in is at a higher pressure than the air in the air bags, otherwise it wouldn't go in. :ylsmoke:

What makes an air spring soft or hard is the volume of air at a given height. Air springs are not just heavy duty balloons, they are actually more like rubber tubes that are mounted to pistons on both ends. The tubes roll over onto the pistons and unroll as the air springs extend. By varying the diameter of the piston at a certain spring length, manufacturers can actually make the off-road setting softer than the standard height setting.

Adjustable height suspension is nice for an off road vehicle and there's the advantage of being able to fit it in to garages more easily, but with solid axles you're not going to get any more ground clearance. I can see the attraction of a variable spring rate so it sits level and handles well when you load it up, and is still comfy when it's unladen. It just seems like a lot of complexity and expense for something that is effectively just a variable rate spring that's actually set up wrong for off road use. If you don't have the variation in payload, then a correctly set up coil spring should (I think) behave better than an equivalent air bag.

You could have a setup that primarily uses coils but reverse-biases them with air, so when you want to lower it you're preloading the springs and tricking them in to compressing prematurely. That might work, but yet more complexity.
Changing the height in an off-road vehicle does much more than allow garage access. Without changing the tires, you are right in stating that a beam axle limits the total clearance under a vehicle, but by lifting the vehicle you are changing the break-over angle. And in a 110, this starts to become a very big deal off road. And a lift allows larger tires which do increase total clearance. On road you have a lower CG which allows safer driving and better performance.

EAS is a good thing. People being paid a lot of money spend years thinking about this stuff before it is installed in a Land Rover. Early systems often don't work too well - not just EAS in a Land Rover but any new system or technology in any sort of product. The RRC/P38 EAS was far from perfect. But the bigger prob IMO was LR's lack of training and information for their own dealer technicians and especially for the aftermarket (indies)(there was a real nice gentleman here on the boards that gave me all sorts of hell for saying this a number of years ago - I'm sure spikemd remembers. Prink.). Later EAS systems are really good. And what makes Land Rovers (Range Rovers) fascinating to me is the combination of on road comfort and off road capability. I've not driven a MB G in a while, but the older ones would not hold a candle to my RRs, and I am quite sure the L405 is much more comfortable and capable than a G on road and equally capable off.
 

rlynch356

Defyota
i think EAS is a good thing, but why retro fit in a defender? simple/reliable/easily fixed (pick 2)..
I'd love to go full TDCI in my truck but again why in the US where my truck will live.. If i go over seas with it then i'd choose a 300 tdi.. first then TDCI

granted i'm coming from a US centric POV and not planning on going international overloading - love to but for the next 10 years is probably a pipe dream at best..
 

MrWesson

Adventurer
Air suspension on the rovers is awesome from a road driving experience and occasional offroading. Instant lift when needed, keeps the body steady, compliant and great for towing. But if you are considering any serious offroading or overlanding, don't do it. Its another complex system that can go wrong and leave you stranded. I loved the EAS (air suspension) on my P38 and kept it up for a few years until my buddy, with brand new Arnott Gen3 springs blew out an air spring in Death Valley and had to limp home on bump stops for 400 miles. I ripped out the system the following month and never looked back.

The newer systems on the LR3/4 and Range Rovers are more robust, but I have also seen punctured air lines leave an LR4 stranded and flatbedded home 300 miles. Last month in Baja, an LR3 had a suspension fault and dropped to bump stops. We had to manually jack the car up to reset the EAS computer as it was out of the tolerances of the height sensors. Thankfully, it was a temporary issue, but if your tires are too large and you drop to bump stops, you may not be able to roll. Never a good situation.

I can see why the P38 may have left a sour taste for you and some of what you've seen in the LR3/4.

BUT a Gap tool would have gotten them home more than likely in most scenario's other than complete air failure and even then there's ways to repair the lines on the trail but a punctured bag could be a problem.. I still maintain that you'd be fine with 3 good bags unless you fit too tall tires and they are dragging.

I also see what you mean when it comes to overlanding.. 2,000 miles from home would be a nerve racking time to deal with it.

In the mean time I enjoy sipping my coffee on the trail while my jeep buddies are hitting their heads on the windows. I come out relaxed/rested and they need breaks.

All that is pretty off topic in regards to the Defender and I agree that given its purpose/reputation air suspension just doesn't make much sense to me but there's always people who fit into a market.
 

Cupboard

New member
No. This is actually a very common misconception with air springs. Lifting a certain weight requires a certain pressure. If you do not change the weight, the pressure required to lift that weight will be the same at access height, standard-, and off-road heights. The volume of air in the air bags changes. And yes, the air you are pumping in is at a higher pressure than the air in the air bags, otherwise it wouldn't go in. :ylsmoke:

What makes an air spring soft or hard is the volume of air at a given height. Air springs are not just heavy duty balloons, they are actually more like rubber tubes that are mounted to pistons on both ends. The tubes roll over onto the pistons and unroll as the air springs extend. By varying the diameter of the piston at a certain spring length, manufacturers can actually make the off-road setting softer than the standard height setting.

OK, right, so I think the mistake I made is thinking they were like balloons and needed more pressure to make them bigger.
Although, AccuAir say:

Q: Can I adjust the Spring Rate of my air springs along with the height?
A: Yes, but the Spring Rate will be directly connected with spring height. As you raise the air spring’s height, you will also be increasing the air pressure inside, thus increasing its Spring Rate. Unfortunately, this is opposite from what most of us would want for performance applications, (low and firm for handling, high and soft for mobility).

https://accuair.com/intro

So if I imagine a single acting pneumatic cylinder, with the piston fully out and the port open to air, the pressure inside will be 1 bar absolute. Close off the port, compress the piston half way and then you've got half the volume, pretty much the same internal surface area (slightly less but we'll ignore that for now) and the same number of "air molecules" whizzing around so the pressure will be 2 bar? Say that pressure is now supporting a load, and I add a little more air. It goes in to the cylinder and because the load only needs 2 bar to support it and we've now got more, the piston extends until the pressure has dropped back to 2 bar but the piston is further out. Is that right?

If the load in the vehicle is even and the pressure in each spring is even, then they'll all work out to be at the same extension because if one sticks out further then it will take more of the load. But if the load or terrain isn't even then you'd need a higher pressure in certain corners which is what they use the height sensors for?

Am I heading in vaguely the right direction? There doesn't seem to be that much information online about how the systems actually work.


...by lifting the vehicle you are changing the break-over angle. And in a 110, this starts to become a very big deal off road. And a lift allows larger tires which do increase total clearance. On road you have a lower CG which allows safer driving and better performance.

Yes, I'm aware of that :) I have a 110 and one of your diagnostic tools.
 

Kgh

Let’s go already!
i think EAS is a good thing, but why retro fit in a defender? simple/reliable/easily fixed (pick 2)..
I'd love to go full TDCI in my truck but again why in the US where my truck will live.. If i go over seas with it then i'd choose a 300 tdi.. first then TDCI

granted i'm coming from a US centric POV and not planning on going international overloading - love to but for the next 10 years is probably a pipe dream at best..


Because we can. And the tech is cool. I certainly won't drop that kind of money, but some do. i just thought it was interesting...Rover porn.

This goofy topic has generated a little interest, and some good discussions of why and how these systems work.

And your powerplant comment is spot on. So many Defender "builds" in the US are never going to be able to leave the US, as a 300 TDi or Puma motor in a 1986 110 is a no go for ever bringing it back.
 

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