Need airbag expertise

[darren@ridetech]

Those 2600lb double convoluted bags have a fairly progressive spring rate and not much travel. The Taped sleeve bag will offer a better ride and more travel.

[Tony@AirRideTech]

AirSpring 101

well... first thing is first... at this time we use only Firestone airsprings and there is really no such thing as a 2400 or 2600# bag. That was terminology that was cultivated by the mini truck scene to depict a difference between two of the most commonly used airsprings ( Firestone 224C and Firestone 255 C bellows. ) Oddly enough, their alias names really have nothing to do with any load carrying capacities. For example lets refer to a commonly used 255c. The F6957.... the rated capacity of this spring is 2050lbs of vertical static load @100 psi working pressure. Now if we take an F6873 ( Commonly referred to as 2600 ) will actually take 3150lb of vertical static load @ 100 working psi. Now... Firestone actually makes in the neighborhood of 40 to 50 different types of 255c and 224 c type springs. Aesthetically, you can not tell the difference between them except with the occasional bolt pattern difference. The difference that you need to be acutely aware of will be in the spring rate differences between them. See... when Firestone makes an airspring it is made up of layers of rubber with interwoven sandwiched layers of fabric. They can actually change the intersection points of the interwoven fabric and that effectively changes the spring rate.


You will notice in the aftermarket that there are several different shapes of airsprings that are used. You will more commonly see the double convoluted airsprings and you will also see the widely used tapered or rolling sleeve type springs. These spring are greatly different from each other in both spring rate and rate of progression. A double convoluted airspring ( looks like two stacked doughnuts ) will generally have a short stroke 4-6" total... and it will have a more progressive spring rate. Because it is shorter in height, its short stroke and its progressive spring rate... it is ideally suited to be in an independent front or independent rear end where we have a motion ratio that we need to overcome. A motion ratio is a mechanical advanatage that the geometry of the suspension has over the effected spring. For example... most Mustang II suspension have a roughly 1.6 : 1 ratio. In other words you will see 1.6" of travel at the wheel for every 1" the spring moves.

Now lets take a look at most rear aftermarket applications. Most rear suspensions that are being built these days for use with airsprings are generally some type of link suspension that holds the axle at location while eliminating the leaf springs. In most of these cases you will see where builders are running a tapered sleeve or rolling lobe spring directly attached to the axle itself. By placing them on the axle you are eliminating any kind of motion ratio and working the springs in a 1:1 configuration. In these cases the Rolling lobe and tapered sleeves are better suited. They have a longer stroke and a much more linear spring rate. this makes the vehicles ride quality better, and give more stroke while increasing the performance and making it more tune-able.

If you have made it this far.... you need a beer to let the brain cells cool down and soak up this worthless jargon.....

[1971novaSS]

If you have made it this far.... you need a beer to let the brain cells cool down and soak up this worthless jargon.....

Haha, made it. Damn right! time for the bar. lol. Oh and thanks for the info. I will be putting air ride in on the nova. Very helpfull.

[blazer_man]

Thanks for the info Tony! Nice to hear from someone who really knows the product . I managed to score the bags you recommended from a local guy who had them in stock. He is also going to put the bags I got from brand X on the shelf and unload them for me. I appreciate you taking the time to help me out, I was about to go back to coil overs, but I really want to try this out! I will be in touch when I get closer to needing lines, valves, etc. Thanks for everyone who chimed in, I will have pics in project updates when I get done with the fab work.