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.
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: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.
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.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.
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.
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.
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).
...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.
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..