Want know more about air ride suspension, how easy is it to fit and the pros and cons to driving on air? This Fast Car air ride guide full of tips and hints is for you then…
What is air-ride and why would I want it?
Air suspension isn’t as far removed from the conventional shock and spring kits as you may think, in fact modern kits bolt up in exactly the same way as a set of coilovers would; the one big difference is instead of the car sitting on a coil spring, it’s sitting on a rubber bellow of compressed air. Things aren’t quite as simple as that though, as while in theory replacing an airbag with a spring potentially gives a smoother softer ride, the reason it’s popular in the tuning scene is the fact the suspension height can be raised or lowered.
This is made possible as the bags aren’t pre-inflated, instead they are fed by an air tank and electric air compressor, allowing the car to be raised and lowered simply by filling the bag with more or less air pressure. The reason you would want air suspension is because it’s a damn good compromise between the full performance but static drop of an aftermarket coilover kit, and a hardcore hydraulic setup which not only isn’t good for performance, but in most applications is far from comfortable either.
Air-ride suspension in the tuning scene
You might be surprised to know that aftermarket air-ride suspension kits first appeared for sale to be fitted to cars right back in 1920. As well as for comfort reasons, it was used from the outset as self-levelling suspension for heavy loads, and even fitted to the rear of illegal moonshine smuggling vehicles to stop the back end sagging when loaded p full of booze! One of best known companies in aftermarket air suspension, Air Lift, have actually been around since 1949, and while we tend to associate air-ride as the total opposite of performance tuning, done right it actually can handle well, and was hugely popular in both drag racing and NASCAR in the 1950s and 60s.
With the advent of more sophisticated conventional (passive) shock and spring designs, as well as improvements in tyre technology, the aftermarket airbag scene has mostly concentrated on comfort and looks in recent decades. But with modern kits available that have things such as camber adjustable top mounts and adjustable damping, these days you really can have your cake and eat it. Getting both looks and performance from air-ride is entirely possible.
What components make an air ride system?
Air springs (bags)
These are strong rubber bellows that replace the coil spring of a conventional setup, and come in two main styles, the coilover setup where the bag has a hole through the middle, allowing the shock absorber to travel through it, or the more conventional style where the bag sits separately to the shock. Modern airbags are strong and durable, designed so they only expand and contract up and down, rather than simply blow up like a balloon, and at full inflation run at over 100psi. As mentioned, these are not sealed units, and are inflated with an air tank and compressor to raise the suspension, and deflate to lower it.
If you have a suspension design where the spring is mounted separately to the shock, you can use the very same shock absorber you would have used with your conventional coil spring, but thankfully these days, with the surge in popularity of airbags in the tuning scene, there are now coilover-style kits for a wide range of cars, giving a matched shock and airbag combo. These kits not only make fitting simpler, but they improve handling and ride. Many of these feature shocks with adjustable height platforms for the bags, adjustable damping, and even camber-adjustable top mounts.
Air bags don’t inflate themselves by magic you know, and this is what does the job of sorting out a big, fat supply of high-pressure, compressed goodness. All air suspension kits need at least one compressor and you’ll usually find the one supplied is fairly small and compact, meaning it can be hidden in the boot or spare wheel well with plenty of room to spare. These will happily run off your 12-volt power supply and usually won’t kill the battery in the meantime. The main disadvantage of an air compressor is noise; they’re far from silent, but that’s one big reason for the next item…
In theory you could run air suspension without a tank, but you would need the pump running far too often, and unless you had a week to wait to raise the car, you’d also need a big powerful compressor to do the job. To solve all these issues, an air tank is used as the main supply to the air bags and the air compressor is used to simply keep the tank above minimum pressure. Depending on size, air tanks allow the suspension to be raised at an acceptable speed without the compressor needing to kick in. You just have to decide what’s most important to you; more boot space or a bigger tank.
You need to be able to get the air from the compressor to the tank, and the tank to the bags, and for this you need the air lines. These days most kits couldn’t be easier to install, with simple push fittings and plastic airlines that can be assembled incredibly quickly even for a DIY’er. Just like with brake lines, if you wish you can use solid metal lines throughout, or even heavy duty braided lines to go from the bag to the main body of the car. Both of these options are widely available and relatively simple to fit.
While OEM air suspension tends to be fully automated, the main attraction for fitting air to your car is you’ve got full control over your ride height, and for this you need a little electronic trickery. You have a number of options here, from the most basic single ‘up/down’ switch for the entire car, to one switch for each corner, right up to things like the AutoPilot V2 by Air Lift, which gives you up to 8 preset settings available at the push of a button – not to mention a swanky digital display so you can see exactly what’s happening.
How easy is it to fit air ride, can I just bolt it on and away I go?
If we were writing this feature, even five years ago, the answer would honestly be “hell no”, but for most of us, the days of custom fabrication and rummaging round the parts bin at your local lorry breaker to source airbags are over. These days, there are various direct replacement air-ride kits available for a huge number of popular cars, and the list of applications is growing by the day. While fitting ‘universal’ air-ride kits to a car is still a job for the professionals, for most of us, fitting air-ride is no harder than fitting a set of coilovers, and the job of piping and wiring is so basic almost all of us could manage it with simple tools at the side of the road. It’s 2014 and now we really can fit and set up a full air-ride kit, on our driveways, in a single day. Hallelujah!
What’s it really like to use air ride on a daily basis?
In all honesty? Better than most people expect. A good kit, set up correctly, will handle far better than the conventional suspension a lot of people run, and people have happily drifted and set respectable lap times on air-ride setups. You will lose a little boot space of course with the compressor and tank, but no more than you would with a sub box or nitrous bottle, and there’s very little weight disadvantage by adding the air-ride kit either. While ride height changes aren’t the instant jump they can be with hydraulics, it really only takes a few seconds, and with the right size tank it can be done in silence too. Perhaps the most comforting thing about modern air-ride systems is they’re reliable, and countless people have them on daily driven cars with no issue at all.
What are the pros and cons of air ride?
Pros: Many easy to install, direct-fit kits are now available. They’re easy to use and don’t drastically affect performance or ride quality. Also reliable and suitable for a daily driven vehicle and even on track. Cheap in comparison to hydraulics.
Cons: While leaks are rare, finding them can be a little on the frustrating side. You’ll also lose some of your boot space. You need a decent sized tank to avoid the noisy compressor kicking in when raising the car. Height changes aren’t quite as rapid as with hydraulics.
KW HLS kits – air bags and coilovers?
Ever thought ‘I don’t want airbags, but sometimes I’d love to just raise my car for a few seconds to get over these damn speed bumps’? To be honest most of us have, and that’s where the KW HLS kits come in. These are the usual awesome quality KW coilovers, but with a small airbag fitted along with the conventional spring, allowing the car to be raised up to 45mm to clear speed bumps, steep inclines, and so on. Cheap? No. Awesome? Yes. Check them out at KW Suspensions