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Air bag suspension chat

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Cletus, how long did it take you to flatten the dive tank, and under what sort of use, out of interest?

I did some maths once many moons ago to figure out how long it would last, i cant remember exactly what the out come was but it was something like slammed to full up 18 times before the tank needed a refill.


but in reality you dont do that, i would lay it out when parked but only go up 50mm to drive it.


going to the dive shop was a weekly occurance at least though. $ 5 a fill and wait for 10 mins while they did it.


that was why i went to a york pump, i found i used it less so i didnt have to fill it, which seemed dumb. the last straw was a trip back from coromandel with no air left, every time i went round a corner the air bypassed the valve and got a sag on, had to bump it back up again


( without check valves, the air pressure in the tank must be more than in the bag or when the air pressure in the bag increases ie when going over a bump, the air bypasses the valve and goes back into the tank)

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Ok, the weight in a e30 is slightly front biased (6%) so I'd say with a wagon it'd be brought back closer to 50/50 due to the extra weight in the rear.




So 325kg/corner BUT those bags over strut thingies I don't know how to work rates/volumes out for because they've got a strut in the middle! (affects volume but mostly for rates but it's end cap size in the calc, could guess but bugger it, they must have rates somewhere online)


Lift charts are super helpful if you can find em.
I have a full set for my bags :D hurrah!


If you know the weight (325kg or so ~720lbs) ADD some for you and your gear/missus/mates and then the height (measure) and then look at the chart you will see the approx psi you'll need.
BUT...... (damnit) you'll want to work out any motion ratio as well.
This means it's the distance your car raises vs the amount your bags raise.

A quick lookup shows Rear (0.67) front (1.06) but don't quote me!


So if you're looking at the lift/height chart and see fuck all lift height in the rear don't stress the bag will actually need to do (1/.67) ~1.5 times the lifting so you'll need more psi to bump it up to a respectable level :P


If you're lucky you'll have a ballpark spring rate at X height. You'll find the different rates at different heights too.


And now you can see how much air you'll need to lift front ride height to "up" for those driveways and from "parked" to ride height.

Just plug in your details to my earlier calculation. That'll let you know how many psi minimum you'll need in your 2 gal tank.


Hopefully you're not as confused as I now feel :D

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  • 2 months later...

Hi Guys


Is anyone else running accuair?  I have been asked by my cert guy to disconnect the individual corner controls before he will certify my set up. He says that Im not allowed to operate diagonally opposite wheels at the same time. Only all up & down, front up & down, rear up & down and sides up & down.

How the hell do I disconnect it without butchering the keypad? 

I suppose I can try and open it and remove the contacts inside the keypad



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I have accuair, but with the single switch controller so there is no obvious single corner control.


The rules are pretty clear though, and he is following them.


Yea I understand where he is coming from, it's to stop people doing 3 wheels in their low riders.

I have the remote in my link, can you post a photo of yours?

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Try Getlow customs (I think) in Hamilton, he supposidly made a clip on cover that went over that covered the individual corners and went through a cert,

In saying that mate went through a cert recently with the Accuair controller and didnt get anything said.

I will have to go through this soon as well

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So in theory for $135 usd could buy the switch setup and harness, chuck in for cert, win at cert. take out and back to elevel controller.


Maybe - depends on whether your cert man reads oldschool :)  I have kept with the rocker switch as it's easy to use in most circumstances (sometimes hard to see the light-up colours due to where I have it mounted). Generally I want to be either low, ride, or high. Sometimes the front/back adjustment is handy, but I had never used the corner settings until a couple of weeks ago for a laugh.

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  • 4 months later...

Who knows hardlines on here ? See bullet point facts below :


- I have built a couple of cars with bags, plastic lines are reliable but look shit

- straight runs of stainless are spendy, last time I priced it anyway

- I know nothing of the materials using for solid auto brake and fuel lines

- I have made hardlines for things that flap around in sky and am not retarded

- Cert man says use brake line but it comes in coils and looks a bit shit

- the car guys and commercial hydraulics guys Ive spoken to are useless

- Im assuming ill use JIC fittings ( 37 degree I think )


Is there a golden material that will work ? or do I just use brake line

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I just used some random alloy hard line from Ullrich, cut with pipe cutters and used pushed locks everywhere works a treat for a few years now


Edit: see shitty old pic attached I found on my phone, wasn't that hard to do at all, just need patience and maths :)



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I bought some alloy hardline also which you can buy in straight lengths cut to whatever length you want.

Doing my boot install with hardline at the moment and just bought and bent up then used pushlocks like escortwags says.

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