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Paper Cuts - November 2008 - The Truth About Air Suspension Myths

Questions, Answers, Letters

Max Fish
Nov 1, 2008
Photo 2/2   |   paper Cuts Myths max Fish
After being in the business of building airbag suspensions for nearly 11 years, I have heard some interesting stories about how air suspensions should be set up. I am going to address some of these myths, and hopefully make a little sense out of this often-misunderstood variety of suspension.
Fist off, I want to point out that an adjustable suspension has really only one major design difference than a static-type suspension. If you were to start from scratch and design an adjustable specific suspension, the camber gain should be kept to a minimum and the caster gain (also known as anti-dive) should be minimal-or possibly even eliminated, depending on your needs. The excessive camber that factory suspensions generate as they get lower can be minimized to a 1/2 degree of camber per inch of travel; or less, depending on how often the vehicle will be driven. The caster gain that the factory uses to minimize dive under hard braking can be minimized, or even eliminated in some circumstances.
Myth #1 Camber is only for cornering. I don't need it, because I don't plan on taking corners fast in my truck.
Truth: It is just not a good idea to have zero camber on an A-arm suspension. Even everyday driving can overload the outer edge of the tire and cause excessive wear, as well as make for a poor handling vehicle.
Myth #2 You have to use a sway bar with airbags.
Truth: Strangely enough, the sway bar is most often used by manufacturers to induce under-steer in corners. When cornering, the front tires will loose traction first, which allows the driver to simply ease off of the throttle and regain traction. It's a built-in safety precaution that has been used for many years. Simply put, if the appropriate air spring is used with a quality shock, then installed in the proper manor, the vehicle will not need a sway bar for normal driving situations.
Myth #3 If you use "insert manufacturer here" airbags, you don't have to run a shock.
Truth: This is like saying, if you install 1- ton springs in your 1/2-ton pickup, you won't need shocks. Just because a particular air spring is too stiff for your vehicle, it does not mean you can get away without using shocks. By the very nature of the beast, an airbag has a small amount of dampening, but not enough to consider your vehicle a pleasure to drive, and of course, safety is compromised too.
Myth #4 Airbags won't ever ride as nice as the factory suspension.
Truth: This is my favorite. A properly setup air suspension can ride as nice, if not even nicer, than the factory suspension. Especially in the case of trucks, the factory rarely uses high-end shocks or link systems, so there is plenty of room to improve. The trick is knowing where to use which parts and how to properly install them. A bigger 'bag not only has a higher weight capacity, but a lower spring rate. So, using the right shock is important. Also, a vehicle that only has 5 inches of travel will certainly feel better with 8 inches, but the idea that 12 inches must feel way better is not necessarily true. For a really enjoyable ride on a street-only driven vehicle, I don't suggest more than 10 inches of travel.
The problem with too much travel is the suspension becomes too soft and will wallow over bumps and through corners. I am aware some of you can't even untuck your wheels with only 10 inches of travel, but that is one of the compromises you have to make in order to lay body on a tall tire. It can still ride nice, but not like it could if you were able to balance the suspension with less travel and the proper 'bag and shock combo. Anyone who is reluctantly tolerating the ride quality or their air suspension, because they thought they had to, should be happy to hear this one.
Myth #5 Airbag suspension is unreliable.
Truth: As with anything, the reliability of your vehicle depends on the quality of parts, as well as workmanship. An air suspension vehicle can be very reliable if certain measures have been taken. Properly engineering shock mounts to live through the abuse, reinforcing factory mounts that were compromised in order to make room for the 'bags, making sure that nothing makes contact with the 'bag, using the proper-sized parts to handle everyday driving abuse, and so many more things can go wrong. It's the builder's job to ensure everything is addressed and ready for the road. But unfortunately, no permit is necessary to purchase airbags, so anyone who wants can try to install them, the negative outcomes of which has given airbags a bad reputation.
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