I just did a 2" lift in the rear and while airing up the air bags in the back, the driver side popped? Ordered a new one and it popped within a week of driving.

I don't see any thing that would puncture the bag so I am not sure why they would be popping? Any suggestions?

 

How exactly did you lift the rear 2 inches? With the air suspension you cannot just stick a couple of 2" blocks under the air springs and go. The levelling sensors expect the rear to be at a specific height.

 

Glad you saw this post. So I did the 2" level kit for the back remounted the airbags and put longer shocks on (made for 2-4" of lift). I didn't change anything as far as stock height in the Tech2. I thought that since I wasn't lifting it yet, it wouldn't inflate the springs as much. I am still trying to figure out the tech2 settings and how to set the wanted height. I have been reading posts to try to figure out the tech2. I haven't cut the sensor arms yet so the sensors should be lifting the truck to the stock height. Right?

 

The Tech2 will not let you change anything just test and recalibrate.... This is the thread I made when I did mine where I went into a bit more detail. https://www.hummerforums.com/forum/h...ir-ride-41341/

You will need to do something to extend the sensor arms then get the rear at the correct new height with some jacks and recalibrate the AS module.

 

ok. I have a lift so I can just lift the back where I want it and then calibrate? Do you think it is popping the bags because they are under inflated?

 

Possibly. I'd also check if they are slipping off of the axle. Coil spring spacers get mounted to the spring seat on the axle in place of the factory spring centering puck and in the case of factory air springs you have to remove the plastic puck that keeps the air springs centered on the axle spring seat. All of the coil spring spacers I've seen only have about a half an inch raised center section to keep a coil spring centered on the top of the spacer. The plastic piece that was on the axle seat for the air springs is at least about 2 inches tall to assure the air springs stay centered over the seat on the axle. When I added the coil spring spacers to mine I also modified the plastic air springs centering pucks to install them on top of the coil spring spacers to make sure the air springs stay properly centered over the axle.

As far as just lifting it to where you want and then calibrating I'm not really sure if that would work as the sensors have a limited range (in volts from about .5v to 4.8v if I remember right). That range allows for the full travel up/down of the axle. In the factory setup the sensors at normal ride height are roughly in the center at a sensor voltage of about 2.5v. If you lift but do not modify the sensor arms then the normal ride height might be 4v (just a wild guess) and it might let you calibrate them at that voltage but then the upper range becomes very limited. What would then happen if you pressed the button on the dash to raise the rear or you are off road or in some odd vehicle position (or even jacking the rear up for something)? The suspension module knows by the sensor voltage (using the button on the dash in this example) that when the button is pressed to raise the rear it needs to increase the pressure until the sensors voltage increases by 1.8v. The sensors are on a 5v reference so if you calibrate it with the sensors at 4v and it tries to raise the rear it would probably cause some problems if it expects to increase by 1.8v when that is impossible if the sensor voltage is already at 4v and maxes at 5v.

Its is just unpredictable as to how things would react and work. The AS module monitors the sensor voltages, the air pressures, vehicle speed, whether any door is open, among other things. The best bet is to cut and modify the sensor arms so that the "normal" ride height is still roughly in the center of the sensors voltage range.

 

Ok. I think I get it. I need to raise the rear where I want it, then adjust the sensor arms until it reads 2.5. Then it will fool it into thinking it's still sitting at stock ride height. Correct?

Then should I hit calibrate, or would I even need to calibrate if it is sitting at the correct measurement?

Thanks MixManSC

I modified the lift pucks to allow the air springs to slide over them. I may need to find a way to keep them from coming off the lift pucks.

 

For the lift pucks you might have to cut the raised part off that is for centering coil springs on them and then once it has a flat top you could then bolt the original taller plastic ones on top of the lift pucks with longer bolts. Or you could add a stack of big washers to the inset part of the lift pucks to make the top of them flat enough to bolt the plastic ones on top. The lift pucks are usually inset in the middle some wo if you try to just bolt the plastic ones on top with longer bolts you will just break the bottom out of the plastic ones.

I cut my sensor arms in half, ran a 1/4-20 die down the rods to thread them, and then used a 1/4-20 tube nut to extend them. Once I had it perfect I counted the turns, added locktite and set them back to the length needed. If it matches close enough to the stock sensor voltage you might not have to do the recalibrate. I'd have to do some digging but I think mine at stock height were not right at 2.5v..... You could do with without a Tech 2, pull one rubber sensor arm end loose on each side, turn the ignition on (doors all closed) and carefully adjust them to the position that the suspension does not try to compensate (compressor will kick on to lift or you will hear the deflate valves click open to lower). Be very careful though as it does not take much movement of the arm and if you do not get them both in the right spot the compressor will continue to run and overinflate if you get them in just the right spot though it will neither inflate or deflate. Hard to do both at the same time but both must be in the correct spot. You can then do some exact measuring to see exactly what the spacing is center to center of the posts that each end of the sensor arms go onto and that is the length that the arms will need to be. Pretty sure mine needed to be almost exactly 3/4" longer with the 2 inch spacer pucks in place. I did that at one point when I was fiddling with mine - it takes very very little movement of the sensor arm to trigger it to raise or lower....

In the end it was worth it though..... I found a few pictures from when I did mine. Shows what the stock voltages were on mine. As you can see there was a difference from right to left. I did the stack of big washers to fill the void in the top middle of the lift pucks and got some longer high grade bolts from a parts store. The extra height on the pucks does not bother the air springs at all. Sitting on Cooper STT Pro 37 x 13.5 on 18" forged Weld Racing Cheyenne wheels.