Ever wonder how some of those cars you see parked in car shows get to drive around, when at the shows, they’re completely slammed and laying frame on the ground? Well, they’ve got Air Suspension. That’s right!
While there are many iterations of these, especially the first type, in its basic essence, there are just two types of air suspension systems. Read on to see the differences between the two, the pros and cons of each, and what you should get depending on your needs…
1. Air Bags
Air Bags – This is where you have inflatable rubber air bags in place of your car’s springs. Inflating it increases your ride height, and completely deflating it slams your car either to the ground, your suspension’s bump stops, the lowest setting you adjusted it to on the struts, or whatever point makes contact first.
2. Air Cup Kits
Air Cup Kits – These have been called “bag-less” air suspension systems. An air cup kit consists of pneumatic pistons in the form of aluminum cups, that are installed between the spring, and the top hat / camber plate of a coilover suspension system. When fully deflated, your car is simply sitting on the coilover’s springs. By putting air in it, it pushes the piston, and now acts as a spacer between the spring and top hat / camber plate. The more air you put in, the thicker the spacer, thus increasing the height of the vehicle in relation to the ground.
To understand the pros and cons, we must first understand the purpose as to why these systems were designed in the first place.
1. Air Bags – The original purpose of air bag suspension is to provide a smooth, constant ride quality and in some cases it is self-leveling. Air pressurizes the bag and in turn raised the chassis from the axle. Although traditionally called air bags or air bellows, the correct term is air spring. Superior ride quality compared to traditional steel springs is the reason why air suspension found its way to luxury vehicles. And with the ride height being variable, the vehicle can be lowered for increased aerodynamics and fuel economy at highway speeds, and can be raised to clear obstacles.
2. Air Cups – Air Cup systems were not designed as air bag replacements, being that they are made of metal instead of rubber. Rather, they were originally designed for exotic sport cars that are built with performance-oriented suspension systems, and ground clearance. Air cup kits were “add-ons” as air lifter systems for the coilover suspensions. When activated, it allows the sports cars to raise its height in relation to the ground to maneuver over obstacles. When the air cups are deactivated, it returns the car to its original suspension configuration, sitting on its coilovers, thereby not compromising its geometry, handling, and characteristics.
Here’s a Ferrari 458 Italia with an Air Lifter system installed in front.
Now what are the pros and cons, and differences between the two?
1. Ride Quality = Comfort or Precise Handling?
The truth is, it depends on what your definition of “Quality” is. As the saying goes, “Quality is what the customer says it is”. But if you’ve read the purpose of each of these suspension designs, as described above, then perhaps you already have an idea as to which of these systems will suit you best. Still, let’s try to expound on it…
Air Bags: These would suit you best if “ride quality” for you is all about comfort. There is an optimal pressure (PSI) level that would give you the most comfortable ride. Higher than that, it gives you more height, but makes the bags stiffer. Lower than that, it would supposedly give you a softer ride due to it having the equivalent of a low spring rate, but such is not the case, as the lower the PSI below the optimal pressure, the worse the ride tends to get due to lack of suspension travel.
Air Cups: Now if “ride quality” for you is all about precise handling, optimum control, and driving with a low center of gravity, such as for drift cars, race cars, or sports cars, then what you want to be riding on is a coilover suspension system. Same goes to those with stanced or VIP-styled cars who like to drive as low as possible, static, flush, and dumped, so long as they can still drive and turn safely, then what you want to be riding on is a coilover suspension system. With air cups, you can do all of the above, with the option to lift the vehicle as needed to clear obstacles, speedbumps, or get up steep ramps and driveways.
2. How Low and High do you want to go?
Some Air Bag suspensions allow you to park your car dumped flat on the ground, then raise it up to 8″ high when you want to.
Air Cups, on the other hand, will only raise your car around 3″-5″ from the lowest point you set it at on the coilovers.
3. When do you want to be Low? Parked Only or Slammed Driving?
Air Bags: If you want to drive slammed, you need to keep the air pressure low. As mentioned above, if pressure in your air bags is too low, the ride tends to be softer, but is actually worse due to lack of suspension travel, or you risk scraping your underside on irregular pavement due to the soft suspension. So you’d need to air up a bit more to get that optimum drive height, hence increasing the height of the car from the ground. Essentially, you’d have three ideal settings – the parked height which can be laying frame on the ground, the driving height which has the optimum PSI for road compliance, and then you can raise it up further to full height to clear obstacles.
From L-R: Air Bag Suspension Full Up, Driving Height, Full Down.
Air Cups: For rolling at the height that most people tend to prefer these days, which is driving slammed, flush, static, and dumped, you want something that will comply with the road and is meant to drive with full suspension travel even at the lowest height you set it at. And this is something you can get only from coilovers. So for those who want to ride low and have the option to air up to avoid obstacles, Air Cups over coilovers are your best bet.
Now there is one thing about 99% of the Air Cups out in the market today – they were designed only for you to raise it up temporarily to clear obstacles. They weren’t made for you to ride with air in them, or you risk ruining them. So essentially, you set the coilovers with the “parked” and “riding height” as the same, then you get to air up to avoid obstacles. That’s why a lot of people say you can’t go as low as Air Bags when on Air Cups.
There is one brand that is the exception though – the Phantom Air Cup Kit by Platinum VIP. Theirs is the only Air Cup kit in the market that allows you to drive with air in them. With it, you can set the coilovers at whichever height you want it to be with the Air Cups in the “off position”, and then you’re in full control of selecting your ride height. Now, you can park slammed, raise it up just a little bit to drive as low to the ground as possible, and go full height to clear obstacles. Air is either fed in or drawn out from the cups to raise or lower your vehicles ride height.
Chrysler 300C by Platinum VIP (USA) and Liberty Walk (Japan) on the Phantom Cup Kit
One thing to take note about the Phantom Air Cup Kit is that the more air you put in the cups, the more the coilover spring gets compressed, and therefore the stiffer the suspension gets. Quite the same as what happens with Air Bags, but with Air Cups, you can have a lower driving height at whatever spring rate your coilovers have.
From L-R: Phantom Cup Kit Full Up, Full Down. Full down will depend on where you set the lowest point on the coilovers.
4. What will happen if the system fails?
Air Bags: Failure of an air bag system means your vehicle will be sitting on the lowest position possible when the bags are fully deflated. If it would still be possible to run the vehicle, it will do so with no suspension travel. Worst case is that it may result in complete immobilization of the vehicle, since when fully deflated, the vehicle may rub against the ground or be too low to move.
Airbagged Infiniti G35 tucking tire and laying frame. Note that photo is not of a stranded vehicle but is merely to demonstrate how airbag-equipped cars can lay its frame on the ground when at 0 PSI.
Air Cups: Failure of an air cup system will simply mean that it is in the “off” position. This means that when the air cup is fully deflated, your vehicle will simply be sitting on the coilover’s springs, and will run at that ride height. You just can’t lift it to clear obstacles. With Air Cups, you will never have to worry about bags popping, tearing, or bursting since there are no rubber bags in the system.
Lexus LS430 rolling with the Phantom Cup Kit fully deflated or “off”.
So there you have it. Hope this article gives you more clarity on deciding which air suspension suits you best. Questions? Post it on the comments below!
Plug: For readers in the Philippines, I’ve got good news! The Phantom Cup Kit by Platinum VIP is now available at High Society! <-- Visit and like their page for inquiries/details/pricing. There's an ongoing promo too, so take advantage of it now! Hope to see more air-equipped rides in the Philippines soon. Cheers!
Sources:
Wikipedia
Phantom Suspension
Stance Nation
AGCO Automotive Repair
VIP Style Cars
Scion Life
Night Import
Club Lexus
Speedhunters