I made the (possibly bad) decision to try and use air sleeves on the back of my Model A tudor sedan. No compressor, no tank, just a static setup. I thought it'd be a good idea (this is my first time doing air ride and actually my first time building a car) but now that I've actually tested the sleeves on the car I'm not so sure. I'm using a two link with panhard bar similar to the nascar truck arm setup and the sleeves are mounted immediately ahead of the rear axle. I have two different pairs of Air Lift sleeves - one short pair and one longer pair. With the longer sleeves (4.5" diameter) installed the problem is this: it only takes 30-35 psi of pressure to get the car up to desired ride height but at this height the sleeve is entirely too springy. If I fill the sleeves to get the back end up 2-3" and then sit on the rear cross member that's right over the axle I can actually get the frame to bottom out on the frame. If I stand up the car goes up a couple inches, sit down and the car goes down. If I lean on one side of the car it wants to flop over. Basically, the sleeve is entirely too soft and even if I bump the pressure up to 45-50 psi the spring is still too soft plus the car is now at double the desired ride height. If I use the shorter sleeves (4.0" sleeve) and take them to max extension the spring rate actually "feels" good and the car doesn't flop around as bad. But having the sleeve at max extension is obviously no good. Some questions and observations... First, is my car potentially too light for air bags? It's only a body, frame, and engine/trans now. The engine/trans is all aluminum and weighs less than 350 lbs. No interior, fuel tank, battery, etc., in the car yet. It appears that the larger diameter sleeve is almost always softer feeling than the smaller diameter sleeve. Are bigger bags softer than smaller bags? I don't want the ride height to change +/- 2" every time I get in or out of the car or fill up the fuel tank or whatever. What do I need to do in order to accomplish this? This will literally be the biggest kick to the nuts if this setup doesn't work. I've spent so much time setting this up and building it in a unique way to make things clean and packaged well. I'd really fuckin' hate to have to cut it all off and start over again. Please help!!
Either bag has its place in a properly set up suspension. You need to find out (manufacturer specs) what proper "ride height" for each spring is, and then set up top and bottom mounts accordingly. My truck (definitely heavier than yours) runs 25# in the rear bags, and works fine. Tell us more about your bag model numbers and/or mfg specs.
Shocks are going to help a lot with the flopping around, and the springing. You need shocks. Without them your just riding on a balloon.
Ah ha. Okay, yeah still no shocks on the car yet. I didn't think it'd make that big of a difference but I assume it does?
I don't think you're going to be able to use bags that way on something that light. if you'r car is 1500# with no fuel or passengers and then you add another 500# of passengers and fuel combined then your adding 33% more weight to the vehicle. on a vehicle that weighs 4500# a 500# increase isn't that much. I would keep them on it until the vehicle is in full trim. Definately add shocks. that will keep it from bouncing and swaying so much. Once the car is all dressed out and at full weight see how the bags react. If you still aren't happy with it you could always just go with a coil spring. Or add a compressor and some 1/4 manual valves and make your frame air tight so you don't have to find room for a tank.
You also may consider lowering the mount on the bottom of the bag. this will allow for more air in the bag, and a proper ride height. I would get some shocks mounted first, then make that decision. I also would consider making the lower bag mount adjustable. Once you find your sweet spot, weld them up.
Long sleeves: Air Lift PN 58431 Extended 10.25" Design height 6.5-8.5" Compressed 3.1" Dia 5.1" Max load @ 100 psi 900 lbs Short sleeves: Air Lift PN 58482 Extended 7" Design height 4-6" Compressed 2.4" Dia 4.6" Max load @ 100 psi 870 lbs If I take the all the air out of the sleeves the long ones will extend to 12.5" and the short ones will extend to 9". With the frame sitting on the axle (aired out) the distance between the upper and lower mounting pads is 5.75". At 2" of ride height (a smudge under desired ride height) the distance is 7.5". Desired ride height is 2.75-3.00".
Sounds like the bag mounts are a little too far apart also. Use the 9" bag, bring your mounts closer together.
All good ideas but I'm kinda stuck with what I've got now. The lower pad is mounted to the top of the link and it can't go any lower. I can however make a spacer to effectively raise the pad up. I thought about using the So-Cal gas shocks but I read somewhere on here that non-gas shocks may actually be better for air suspension. Thoughts?
Your going to have to move the lower bag mount, its got to be closer than what you have it at now, or it aint gona work. Once you get your bags working correctly, then you will know what size shock you will need. I have always used S10 pickup shocks.
Okay, I certainly appreciate the suggestion and it makes sense if I were to use the shorter sleeves. But, shouldn't the longer sleeves also work? I mean I made the pad distance at desired ride height exactly in the middle of the sleeve's design height. The longer sleeves are being used exactly as they're spec'd. BTW the 58431 sleeves are from the old Air Lift S-10 air suspension kit.
Truthfully, I really want to use the longer sleeves if I can. The bigger sleeves have a metal top with a 1/2" port and two 1/4"-20 mounting holes and of course I already made my upper mounting pads specifically for this pattern. The other sleeves I have have a cheesy plastic top on them with a male threaded stud that sticks up. Will good shocks tame my longer squishy sleeves? Or are the shorter ones my only hope? Getting shocks on the back of the car will be my next project.
I think the shorter bags are going to ride better, less bounce at ride hight, your car is light. Also, the bag wont bunch up when its lowered. I dont see any lower bag mounts anyway, and I hope your not going to use those trailing arms, they aint gona hold up. You can use the taller bag i guess.
Ah shit, what's wrong with my arms? They're 1.5"x2.5"x.120" with 1" uniballs in front and big ol plate flanges in back. I've used the same thing on a long travel off pre-runner truck and had no problems... and that was jumping the thing 6 feet in the air. The mounts are the round discs under the sleeve. They bolt to the sleeve and then the whole thing bolts to the arm.
Well thats a lot better picture, the other shot looked like square bar stock. Those look really good, and the welds look good too. Good job. Ive got a squarewave 175 pro too.
Yeah, great welder. I love mine. Got it for a song. Think I'm going to upgrade to a water cooled torch soon even though 90% of the high amp welding work is already done on the chassis. Okay, new game plan. Get shocks mounted up and see how things feel. I'll report back later. And by later I mean probably a month or two. I tend to spend more time researching, designing, and prepping than I do actually doing the physical work. Thanks for everyones help... especially you Bishop.
Currently "2600" type convoluted, but I have used "f9000" style sleeves as well. In my OP, I ASSumed you had shocks. As others have mentioned, you NEED shocks to make any real assessment. (Air) springs suspend the vehicle. Shocks control the oscillation of the spring. Also, as others have stated, and to my original ride height comment, you need to get the bag into proper ride height range... period. Make a spacer if you must.
Yea, I need to water cool mine. I bout burned the head up trying to weld aluminum. Let me know what you end up doing as far as parts go for the upgrade, I really need to cool mine. Keep us updated on the build.
The longer sleeves are at the proper ride height range... right in the middle in fact. But they were still super bouncy thus my concern. The short sleeves are just that... too short. They were sent to me by accident by the guy I bought them from and then I got the longer ones which were what I was expecting in the first place. Anyways, like I was saying, I guess I gotta get some shocks on before I say yay or nay. Thanks again guys.
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