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Discussion Starter · #1 ·
"Airride doesn't handle Good!"
"Airride rides like crap!"
"Airride is too soft!"
"Airride is unreliable!"

Thes are all comments that any air loving person has had said to them, or has heard said.
I want to bring this thread up, to see what people think?
I believe that with the right components, installed right, you can have a reliable,
well perfoming setup that can compete on a circuit, and still be comfortable and practical in a daily setup.


My experience with air, and the cars i have been in with air has been completely positive.
As we have seen with Airride Technologies, and Praxis Advanced Suspension, it is possible to build a car with airride,
and compete on a competition level.



So why all the negativity? Why all the hating on Air? Its practical, Its comfortable, and it has the ability to perform well!
If anything, i could see the price being the only issue that would cause somone to consider airride to be a bad decision.
And this is purely on the basis of its function, and not the fact that it gives you an unmatched stance.
What is your experience with air?
I understand that "air shocks" and cheap components is not the way to a performing airride setup;
but that does NOT mean that its not possible.

My experience on my A8, A+, it was comfortable, reliable, practical, and i never had handling issues that made "airride" a bad decision.
But i have to mention, my car was not a performance car, by any means!


Modified by theflygtiguy at 6:14 PM 12-19-2007
 

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Re: AirRide and Performance. (diive4sho)

I agree with Mike on this one, my car is bagged and handles almost as well as it did with my Tein SS coilovers on it. With a little tweaking, I could easily match or surpass the handling abilities of my car with coils.
 

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Discussion Starter · #4 ·
Re: AirRide and Performance. (diive4sho)

Quote, originally posted by diive4sho »
Proof that bagged cars can handle
http://youtube.com/watch?v=Fn8XKR4Q9CU

Not to mention that in this video, they look like they are using standard struts.
Coupled with something like a Koni Yellow Adjustable dampening, i'm sure this would be even better.
 

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Re: AirRide and Performance. (theflygtiguy)

I think the issue comes when you get down to the details of dealing with simulating spring rates with bags. The benefit of coilovers is that you can pick a spring rate keep and keep it at every height, where as with air ride adjusting the spring rate is linked to the ride height until the maximum ride height is reached, and then you can only increase the spring rate. Also, because each coil in a spring can be wound differently, you can modify how the spring rate as the spring is compressed for progressive rates.
Optimally, I think for a good handling air ride setup, you need to pick the right bags and mount them so that at the track/performance ride height you want (with optimum suspension geometry/low center of gravity) and you also have the right pressure in the bags to achieve the spring rate you want. If I were doing it (and I sure would like to
) because I don't have any experience, I would probably have choose to have the bags fully inflated at track height and hope that the optimum spring rate can be achieved by adding additional pressure. This works out with my goals of raising my car for tracking anyway, though I still haven't though through how to deal with camber issues, (ie I want more aggressive camber when I raise the car)
Both can use the same dampeners, so you could adjust compression/rebound with however good a shock you purchase.
I haven't done enough research on the matter to say definitively, but I just don't see a way air-ride can match the fine tuning of spring compression rates to be truly competitive. I'm sure it possible to put together a well thought out great handling air-ride suspension, probably better than some coilovers, but it seems like that it still has some limitations when you really are looking at building the best handling suspension.
 

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Re: AirRide and Performance. (dedgsus)

Actually you would be suprised..
I know for a fact that the Universal Air Suspension's Aero sport bags when used with a 1/2" air line have a average spring rate of 300lb/in...the smaller the airline the stiffer the rate. The bags are also progressive in the fact that the "middle" air pressure setting will be the most comfortable ride and the softest spring rate and the MAX psi of 200psi will give you a stiffer rate...a lot stiffer actually......Also in the lowest setting you basically have no support by the bag so the spring rate is very stiff...although I don't think you'd want to track at this height. Vehicle weight also has a lot to do with the feel and handling of airsuspension kits....the same air suspension on my Audi allroad (4,212 Lbs) would feel much stiffer on a mk2 or some other lighter vehicle...
Another thing most people don't think about is the spring rate in relation to the size of the airline leading to the bags....yes it makes a difference....it's a lot like brakes....people switch their brake lines to stainless steel braided lines to reduce the flex of the line and it increases their brake response....well I'm not saying go full braided lines for better performance but I am saying that air suspension lines have flex in them as well...so this has to be considered when determining spring rate. Also the more air in the lines the more space for the air in the bags to divert to when the bag is being compressed by the shifting weight of the vehicle...so smaller lines will give you a higher springrate because there will be less back flow into the lines. And last but not least, also most obvious, a FB system won't handle as well as a FBSS system.....with a FB system there is a T in the line coming off of the valve that splits to both bags and this allows the one valve to controll both bags (front or back)....Imagine going hard into a right turn and most of the air in the left bag goes through the line through the tee and into the right bag.....so not only do you have flex of the lines but you have flex of the joined air bag and this will greatly increase body roll and decrease spring rate......I think it goes without saying that some factors of air suspension systems are very complex....spring rates is one of the most complex in my opinion.




Modified by diive4sho at 5:26 AM 12-21-2007
 

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Re: AirRide and Performance. (Starion88esir)

Quote, originally posted by Starion88esir »
You can easily install check valves at each corner (which should be done in both FB and FBSS set ups anyway) to prevent and unwanted leak down.

If you do this how do you deflate the bag?
 

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Discussion Starter · #10 ·
Re: AirRide and Performance. (diive4sho)

Quote, originally posted by diive4sho »

Another thing most people don't think about is the spring rate in relation to the size of the airline leading to the bags....yes it makes a difference....it's a lot like brakes....people switch their brake lines to stainless steel braided lines to reduce the flex of the line and it increases their brake response....well I'm not saying go full braided lines for better performance but I am saying that air suspension lines have flex in them as well...so this has to be considered when determining spring rate.

I was thinking about this too, since you would be losing pressure from your bag into your air line due to flex in the line
I'm sure that even a few psi of difference in the bag would make a big change in handling.
Talking to some friends, and doing some research i have been throwing around the idea of doing hard lines on my car.
Doing 1/4 inch hard lines with AN fittings, and 1/4 inch valves.


No different than doing brake lines really.
It would make all the cleaner of an install, and Zero Flex.
 

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Discussion Starter · #11 ·
Re: AirRide and Performance. (Florida Flow)

Quote, originally posted by Florida Flow »

If you do this how do you deflate the bag?

you could probably have these check vavles installed on a seperate circuit, and if you know your going to be throwing the car into the corners, simply throw the switch to close the check valves... when your done, throw the switch, and you are back to your standard valve setup.
i dont know how this would work though... you'd probably want to install these checks as close to the bag as possible.
 

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Re: AirRide and Performance. (theflygtiguy)

Quote, originally posted by theflygtiguy »

you could probably have these check vavles installed on a seperate circuit, and if you know your going to be throwing the car into the corners, simply throw the switch to close the check valves... when your done, throw the switch, and you are back to your standard valve setup.
i dont know how this would work though... you'd probably want to install these checks as close to the bag as possible.

Ya thats what i was thinking. I really dont think that is nessarry just somthing else to go wrong/break.
 

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Re: AirRide and Performance. (Florida Flow)

Quote, originally posted by Florida Flow »

If you do this how do you deflate the bag?

You would either need to move the dump valve very close to its respective 'bag or run two airlines from the valve manifold to each 'bag; a standard check valve will only flow in one direction.
You can run a FR setup without the "negative swaybar" effect if you use 2 check valves per corner and a handfull of extra T's. At $4-8 per fitting and $10 per check valve, this will almost always be more expensive than another valve.
The most important reason why longer air lines make a system softer is that there is more air to compress. Brake fluid is basically uncompressible, so flex in the rubber hose is the issue. Air is a compressible gas, and "stiffness" of an airbag is a function of the air volume in the system. You can improve stiffness by mounting the valves closer to the 'bag or running smaller diameter air line.
For example: say you have two air cylinders with the same bore and they're both fully extended at 100psi. One is 20" long and the other is 2" long, and you compress each one 1". It will take more force to compress the shorter piston because the volume is reduced by 50%, where the longer cylinder only decreases volume by 5%. If anyone wants me to elaborate I can post some actual numbers and equations later.
As far as racing with airbags, air springs are far too unpredictable and inconsistent to be used in a competitive racing situation. Having air in the tires is enough of a hassle, imagine if your spring rates changed with temperature and humidity also!


Modified by Afazz at 3:29 PM 12-21-2007
 

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Re: AirRide and Performance. (Afazz)

Another thing to keep in mind when thinking about line flex for airlines is how strong DOT air lines are. The average car with air ride generally maxes out around 100psi. DOT air lines are rated FAR higher than that and I've seen max PSI tests done on air lines and the line didn't even begin to flex and balloon until 700+psi.
 

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Re: AirRide and Performance. (Afazz)

Quote, originally posted by Afazz »

You would either need to move the dump valve very close to its respective 'bag or run two airlines from the valve manifold to each 'bag; a standard check valve will only flow in one direction.
You can run a FR setup without the "negative swaybar" effect if you use 2 check valves per corner and a handfull of extra T's. At $4-8 per fitting and $10 per check valve, this will almost always be more expensive than another valve.
The most important reason why longer air lines make a system softer is that there is more air to compress. Brake fluid is basically uncompressible, so flex in the rubber hose is the issue. Air is a compressible gas, and "stiffness" of an airbag is a function of the air volume in the system. You can improve stiffness by mounting the valves closer to the 'bag or running smaller diameter air line.
For example: say you have two air cylinders with the same bore and they're both fully extended at 100psi. One is 20" long and the other is 2" long, and you compress each one 1". It will take more force to compress the shorter piston because the volume is reduced by 50%, where the longer cylinder only decreases volume by 5%. If anyone wants me to elaborate I can post some actual numbers and equations later.
As far as racing with airbags, air springs are far too unpredictable and inconsistent to be used in a competitive racing situation. Having air in the tires is enough of a hassle, imagine if your spring rates changed with temperature and humidity also!

Modified by Afazz at 3:29 PM 12-21-2007

Thanks for the great info! Def answered my question.
 

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Re: AirRide and Performance. (Florida Flow)

i run 1/4" lines and it handles amazing, better than any coils i've ever owned.

but then again, the lines are just one part of the equation, **** shocks and struts and great bags will still handle like ****
 

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Re: AirRide and Performance. ([email protected])

wow, the amount of misinformation in this thread makes me want to punch a goat...
the airline itself has no effect on handling. it does not expand with pressure unless, for some weird reason, you are using non-reinforced rubber hose(& i've seen people do it
).
second, a check valve would have little to no effect on handling, but it is a good idea to run them anyway, in case of airline failure. a good valve will have no leakage anyway, so when aired up, the bag will be full, as well as the line going to both valves. if you have good valves that won't leak, where is the air gonna go? now, if you're only running a 4 valve, front/back setup (and if you are & you're worried about performance, you need to order 4 more valves before you even THINK about a track), the check valves would be a good idea. it's be a pain to plumb all the lines to make it work correctly, but it can be done. me, i'd just do an 8 valve setup & call it a day.

also, the spring rate with bags is progressive and adjustable. for optimum performance, measure your desired ride height for the track, & set up your suspension so it is at 1/2-2/3 stroke at that height. my car, at a little below stock height, & at around 80psi in the front & 60psi in the rear, feels like it's on coils. it goes about 3" above stock height & like 7" below
so, i'm right around that 2/3 stroke. at full pressure, 'bagged vehicles are so stiff it's hard to drive them, so i wouldn't recommend racing it that way, nor would i when it's totally aired out. right around midway-ish should be perfect, if your're set up right.
oh, and 'bagged cars don't max out at 100psi...mine has a 150psi pressure switch. i used to run my passat at 180psi. all that means is with higher pressure, it airs up faster. my car will straight up bounce off the ground at full pressure. i could hop my last truck...that was fun for showing off
but i never have more than 120psi in my cylinders at any given time...except for some of those stupid speed bumps


ok, i'm really sorry for the long, probably confusing post, i just woke up & my head hurts.
kthxbai.
 

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Re: AirRide and Performance. (beyondkustom)

Quote, originally posted by beyondkustom »
second, a check valve would have little to no effect on handling, but it is a good idea to run them anyway, in case of airline failure. a good valve will have no leakage anyway, so when aired up, the bag will be full, as well as the line going to both valves. if you have good valves that won't leak, where is the air gonna go?

I never said it effected handling. I said it will prevent any unwanted leak down. As you can see a good bit of the posts on this forum are from people who either don't know how to set up a system, are trying to go the cheapest possible route or are misinformed.
My Civic (yeah yeah yeah) will hop off the ground with the pressure at 150. It's nothing major, just from a fast fill and that's with only 3/8 lines and valves.
But back on subject, I know of only two valves that are leak proof and most people don't use them. Most use SMC valves on the set ups I've seen.
 

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Re: AirRide and Performance. (beyondkustom)

Quote, originally posted by beyondkustom »
wow, the amount of misinformation in this thread makes me want to punch a goat...
the airline itself has no effect on handling.

Sorry to burst your bubble but it does have an effect on spring rate and in turn effects handling....I know this for a fact....If you want the stats on how the size of an airline effects the spring rate of a universal air suspension Aero sport bag (which a lot of people on here are using) just call richard over a UAS. I'm not trying to be snippy or rude...just letting you know that it makes a difference.
 

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just came across this thread, and have also been doing some research. for the mk3's Mike especially, Ive been talking to Scott at Masontech for a while now, and his kit seems pretty damn complete. I have also been thinking about doing the hard lines too. I decided to go for an air setup over coilovers.
Suprised that Scott hasnt chimed in yet
here's the link
http://www.mason-tech.com/default.asp


Modified by UBER KUHL at 9:54 PM 12-26-2007
 
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