Riding on Air - What is Air Suspension?

Suspension plays a pivotal part in providing a smooth and controllable vehicle, keeping the tyres in contact with the road to maintain consistent traction. If you didn’t know already, there is more than one way to stop your bones from crumbling in a vehicle. One that is popular in the aftermarket world is air suspension. A practical way to have your car sit as low as possible. This is your introduction to the world of air ride to dial in that wheel fitment whilst still being able to take your mother-in-law to the shops.

You might have heard of suspension before. Most would usually picture a spring and a shock absorber as the system to provide a comfortable ride and to keep the wheels in contact with the road. It’s the same concept with air suspension, however, instead of a spring (coil or leaf), just imagine a rubber cylindrical or two ball-like shape filled with pressurised air to provide resistance from lateral movement due to uneven surfaces in the road.
Manufacturers have adopted air suspension for production vehicles due to its ability to iron out bumps and provide some adjustability on the go.

Let’s roll back to the 20th century, more specifically, 1901 when British engineer, Archibald Sharp came up with the initial pneumatic “rolling mitten seal”. The first design was intended for bicycles soon made its way onto trucks, planes and eventually, the motor car. In 1949, Claud Pemberton founded Air Lift, a family-run business, that developed an air spring that would be fitted to a car. Air Lift found its way into stock car racing and found popularity among drivers after seeing what its revolutionary technology was capable of. Eventually, air suspension took a detour into luxury cars in the ’50s, promising a smooth and comfortable ride. Fast forward to today, and it’s not just about comfort; it’s about practicality, and adjustability whilst retaining or improving performance.

Air suspension carries a bad reputation among some car enthusiasts who love performance cars. Many don’t see air suspension as a viable option if you want your car to handle at its best and prefer a coil spring design. I get it. If BMW fitted the M2 with air suspension from the factory, you’d ask “What on earth were they thinking?” However, it’s a misconception that air suspension doesn’t perform well at all, and here’s why you’d be naive to think so.

Audi, Acura, Bentley, BMW, Cadillac, Citroën, Ford, Genesis, Hummer, Hyundai, Jaguar, Jeep, Land Rover, Lamborghini, Lexus, Lincoln, Mercedes-Benz (and Maybach), Porsche, Ram, Rivian, Rolls-Royce, SsanYong, Subaru, Tesla, Volkswagen, and Volvo.

All of these car manufacturers utilise air suspension on at least one of their production vehicles. As you’ll probably notice, the majority of these manufacturers produce luxury cars, and while they aren’t lacking in the performance department, the vehicles equipped with air suspension aren’t setting lap records on the Nürburgring. The point I want to make is that these manufacturers know what they’re doing and aren’t going to compromise if it isn’t up to the job. An air suspension setup is more than capable of producing an adequate spring rate, which is determined by the pressure inside the “air spring”.

Air ride has been in production for 75 years now, but has become increasingly popular in the last two decades. What’s behind the hype of air suspension?

In one word. Fitment.
It’s not just about going low; it’s also how your wheels sit in your wheel arch. I like to think that wheels are the footwear for your car. You wear different footwear depending on your activity. The same is true for wheels.

There are different types of wheel fitment. You might want to tuck your wheels inside the wheel arch, have them poking out a little or have the arch and wheel sit flush with each other. There is more to it than that, but when you break it down, it’s all for looks. The benefit of air suspension is having the ability to air your car out so you can have it consistently sit parked in its best form and then raise it back up to drive home without a scrape. Air suspension is the innovation that allows you to win at both; aesthetics and practicality.

This craze has sprouted a new branch in the automotive world that has led to the growth and start of many businesses. Wheel manufacturers such as Rotiform and HRE have flourished due to the rise in popularity of stance fanatics. For this reason, both manufacturers of air suspension and wheels have great relationships because of how air suspension and wheels complement each other.

Adjustability

One of the significant advantages of air suspension is the ability to adjust the ride height. This feature allows drivers to raise or lower the vehicle based on driving conditions, preferences, or in the cases of production vehicles, improving aerodynamics on the highway or increasing ground clearance. For aftermarket, the ability to be able to “lay frame” or to air your car out as low as you want when parked.

Comfort

Air suspension provides a smoother and more comfortable ride compared to traditional suspension systems. It can absorb shocks and vibrations more effectively, resulting in a more pleasant driving experience, especially on rough or uneven terrain.

Customisation

Most aftermarket air suspension systems can pre-set programmable settings, allowing you to customise your pre-sets for different heights or suspension characteristics. With production vehicles, suspension heights are usually determined by driving modes. E.g. Off-road modes would raise the suspension for more ground clearance.

Load/Height Levelling

If equipped with the sensors, vehicles fitted with air suspension systems can automatically adjust to maintain a consistent ride height, even when carrying varying loads. This is particularly beneficial when you still want to maintain your practicality, being able to carry passengers and load up your boot with luggage, slabs of concrete or lumps of cast iron. Whatever inflates your bag.

Maintenance

Air suspension systems typically require more frequent and specialised maintenance compared to traditional suspensions. Regular checks for air leaks, proper functioning of electronic components, and overall system health are necessary, adding to the overall ownership costs.

Complexity

Air suspension systems are more complex than your standard coil or leaf configurations, involving electronic components; electronic control modules, sensors, and air compressors. Although it is a fairly simple system, the additional complexity over a traditional system can lead to more potential points of failure, further resulting in increased maintenance costs.

Additional weight

The components of air suspension systems, including air compressors, tanks, and airbags, add extra weight to the vehicle. This additional weight can impact fuel efficiency and overall performance, especially in terms of acceleration, braking, and handling.

Reliability

Air leaks or malfunctions in the system can leave you stranded. Having issues away from tools is a heck of a lot more painful than a regular breakdown. If you have an air leak and can’t get air back into those air bags or they no longer hold pressure, you’re going to have a hard time. On top of this, maintenance and repairs can be more challenging and costly in most circumstances, requiring a good knowledge of the system and some tools you won’t find in a hobby toolkit.

Limitations in Performance Driving

My personal opinion has always been that air suspension isn’t as capable on the track as coilover suspension, but I’m open to being proved wrong.

Cody Miles is doing exactly that with his Subaru equipped with Air Lift’s Performance Series suspension, setting several track records and podium finishes across the U.S. (Pictured below).

I do believe that you can still give your car a beating, it’s just that air suspension systems may not offer the same level of precision and performance as coilover suspension when you’re trying to set competitive lap times. The characteristics of air suspension may not be as beneficial to aggressive cornering and handling when compared to coilover systems.

Fitting air suspension will require more than just installing air bag struts. You will need to find a place to fit a compressor, air tank, controller, and manifold, from which you would need to route the lines through or under the car to each air bag strut.

Some cars may require modifications to the body or the chassis of the car. For example, some vehicles require something called a “chassis notch”, which is the process of removing material and reinforcing a structural part of the vehicle to prevent components such as driveshafts from hitting the chassis leg.
You will need to maintain the system. This would include draining condensation from the air tank and routine inspection of air lines, collars and struts. In cold climates, you may need to add a cap full of air brake anti-freeze every month or two, depending on your usage.

The answer is, it depends on the purpose of your car. As I’ve mentioned before in my introduction to automotive tuning, it’s all about your preference and finding what suits your vehicle’s application. If you only want to take your car on a track or want basic suspension adjustment and don’t want to frequently adjust your ride height to get over speed bumps, I’d stick to a traditional coil spring suspension setup. For most other uses, air suspension is plenty practical and capable of performing well on the road and track if that’s the route you want to take. You can still beat on it, but there isn’t as much adjustability with an air suspension set-up compared to a coilover with camber plates etc.

There is a stigma with air suspension that it isn’t reliable. It’s only unreliable if it isn’t installed properly or tested thoroughly before driving it out of the workshop. I got involved with a small handful of air suspension installs during my time, and it can be a long process to get everything right, but in the long run, it’ll pay its dues. If you rush the testing of the system and wheel fitment, you’ll only be setting yourself up for failure. Always test and check the fittings and wiring, check for kinks in the air lines and do thorough testing of your wheel fitment. If your wheels get too close to the air bag and start rubbing, you’re going to have a bad time. Once you start rubbing through too far, you will reach air, resulting in the air bag being split open, preventing it from holding air, leaving you stranded at the side of the road.

Do your research before installing an air suspension system yourself, or take it to a professional with experience.

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