PROBLEM Bagged B5

[clumsy me]

I just finished installing an airlift kit with accuair switchspeed. I am having an issue similar to the other guy with the E90. My problem is I cant get the rears to get high enough. They move up and down with air pressure but they are too low for driving even at full pressure. I have the threads on the shock topped out and I still cant get the tire to clear the fender. The fronts work great but I cant the rear up.

I am planning to call airlift in the morning and see whats up but I figured I would also ask here to see if anyone has any insight.

[Oh Damn, it's Sam]

Is the bag fully extended at maximum pressure?

[clumsy me]

Is the bag fully extended at maximum pressure?

Its hard to tell, this is my first time with bags. I can take a pic and post if you can tell that way

[Oh Damn, it's Sam]

You have sleeve-style bags in the rear, correct? You should be able to see the full lower lobe / piston if the bag is inflated all the way. But, a picture never hurts either.

EDIT: The bags shown in the B5 kit on Air Lift's website look like they're fully-extended. If that's what your bags look like at ride height, they're all the way up.

[clumsy me]

You have sleeve-style bags in the rear, correct? You should be able to see the full lower lobe / piston if the bag is inflated all the way. But, a picture never hurts either.

EDIT: The bags shown in the B5 kit on Air Lift's website look like they're fully-extended. If that's what your bags look like at ride height, they're all the way up.

yes they are a sleeve style bag.

This is what the bag looks like aired up.


I messing around trying to figure it out and I noticed that if I air the car up with the wheel on the ground I can get up to 24 1/4 ftg BUT if I jack one of the wheels off the ground and air it up with the wheel in the air and then let it down off the jack it settles at 26 ftg.

[Oh Damn, it's Sam]

Weird, I didn't know they mounted the bags upside down on the B5! Interesting.

It's not surprising that raising the corner first allows the corner to go higher, but that does tell us you have some additional upward range you could get out of the bag. The problem is, you don't want to drive fully-inflated, as it's extremely hard on the bags, so we're probably going to want to figure out a better solution than just "cram a shitload of air into them."

If you inflate from zero, what pressure is each rear bag sitting at when full?

[clumsy me]

Weird, I didn't know they mounted the bags upside down on the B5! Interesting.

It's not surprising that raising the corner first allows the corner to go higher, but that does tell us you have some additional upward range you could get out of the bag. The problem is, you don't want to drive fully-inflated, as it's extremely hard on the bags, so we're probably going to want to figure out a better solution than just "cram a shitload of air into them."

If you inflate from zero, what pressure is each rear bag sitting at when full?

Yea they mount them upside down because of the way the shock mount is. I dont wanna ride around at full pressure. :/

Inflating from 0 while on the ground I get to about 90 psi then the bag goes more out then up. and that gets me to between 24 - 24.5 ftg. I am aiming for more like 26 area for driving

[Oh Damn, it's Sam]

Max PSI on those bags is 125. At 90, their lifting capability is only about 1100 lbs each, and with the motion ratio of the suspension, they need to be able to lift at least 1000, which doesn't even take into account the angle of the suspension arm. I'd be tempted to throw another 10-20 psi in them and see where the car settles.

[clumsy me]

Max PSI on those bags is 125. At 90, their lifting capability is only about 1100 lbs each, and with the motion ratio of the suspension, they need to be able to lift at least 1000, which doesn't even take into account the angle of the suspension arm. I'd be tempted to throw another 10-20 psi in them and see where the car settles.

After about 100 psi the car doesnt go up much it looks like the bag just goes out instead of up.

I talked to airlift again and sent a bunch of pictures they think something is wrong in the valving of the shock that it is keeping it so low. They might be sending me a new set of rears.

[Oh Damn, it's Sam]

That seems... weird to me, but I'm sure they know what they're talking about. Keep us posted.

[clumsy me]

That seems... weird to me, but I'm sure they know what they're talking about. Keep us posted.

So airlift finally got back to me and offered no real solution. They told that is just the way yours are.... nevermind that everyone else with my same setup doesnt have any of the same issues.

There final suggestion is to make the shock stiffer and run at 120 psi with no assurance that it wont mess anything up.

And on the issue of the rear going too low they told me to drill a lower hole in my shock mount. Which to me doesnt seem super safe and like a real solution on their part.

[Oh Damn, it's Sam]

What? Unless I'm completely misunderstanding something, none of that makes a damn bit of sense.

If they're trying to use a stiffer shock to control the compression of the suspension when cycling to keep the bag from going over its rated pressure, that's dumb. It's better to run over-damped than under-damped, but that is not the job of the shock absorber, that's the job of the spring. If the air springs are that close to burst pressure at ride height that you have to artificially limit their travel via some kind of dumb hack like that, their burst pressure isn't high enough or they're too small for the application, period.

I also doubt very much that moving the upper eye of the shock downwards is going to help, since you're already maxed on your adjusters to no effect. The issue is that the air pressure in your bag is only sufficient to get the LCA to a certain angle relative to the ground, with that angle being related to your ride height. Since the force needed to continue lifting the car is related to the angle (on a typical swing-arm suspension, it's proportional to the inverse of the sine of the angle of the arm relative to the central axis of the bag), moving the shock is not going to help, since at 90 psi, it can only exert so much force, no matter how high or low it's located.

Since this setup appears to work for others, I suspect you've got a fouled up bag that doesn't want to continue rolling beyond a certain point, which is why you're stuck at this height and why more pressure balloons the bag without raising further.

[clumsy me]

What? Unless I'm completely misunderstanding something, none of that makes a damn bit of sense.

Since this setup appears to work for others, I suspect you've got a fouled up bag that doesn't want to continue rolling beyond a certain point, which is why you're stuck at this height and why more pressure balloons the bag without raising further.

It doesnt make much sense to me either... I am trying to figure out what to do at this point because it is obvious that Airlift doesnt want to help or even pretend to...

I am trying to get other people with bagged B5s to send me pics of their rear bags so I can show that something is wrong with my set even after everything I have had to do to show them that there was something wrong they still dont care.

I really wish someone at airlift would return my pm/email or chime in on a thread so they can see everything.

My only option at this point is to take the rear bags out and reinstall my coils because I can get higher with those then the air.

[Imaeechew]

They told you to ride around at 120psi? Do they want you to blow a bag? It sounds like you are getting a bind somewhere. Jack the car up, unhook your airline form the strut/bag and cycle the rear suspension. See if you can get lift that way. Listen/feel for anything abnormal.

[clumsy me]

They told you to ride around at 120psi? Do they want you to blow a bag? It sounds like you are getting a bind somewhere. Jack the car up, unhook your airline form the strut/bag and cycle the rear suspension. See if you can get lift that way. Listen/feel for anything abnormal.

Yea I have been dealing with a guy named Blake at airlift and he doesnt seem interested in helping more just interested in getting me to go away.

I would be ok running at 100 psi because I do understand the avant adds about 100 lbs so I do need account for that but 120 I am not going to do that.

As for listen/feel abnormal. This is my first bagged car it feels less stiff then coils but no weird noises or anything.