Taking control of my airbag suspension that came with my bus

[sekkyoshi]

Taking control of my airbag suspension that came with my bus, 2001 international 36ft 7.3L. Is there any way to override the stock rear airbag system? I need a way to manually and/or separately fill and discharge the airbags safely and reliably. It inflates while running normally to an unknown pressure and bleeds off pressure down to empty when sitting in about two to three days. Additionally the airbrake system bleeds off pressure within 5 to 8 hours of shut down, The airbag suspension will hold max pressure for up to 24 to 48 hours before it starts slowly bleeding off pressure.

Currently they slowly deflate over the course of 6 to 8 hours (usually when I am sleep) making very loud creaking noise as the half leaf spring pack grinds against itself literally every 7 to 10 seconds for 8 hours. Six months ago when I first got the bus I thought the noise was someone knocking on the door or underneath trying to steal stuff. So I would run outside trying to catch burglars at 2 AM... that weren't there.

Back in the 90s I had a Toyota Corolla wagon that I installed a aftermarket airbag suspension on. My last home, a gas Class C rv came with aftermarket airbags that had seperate schreider valves on each side, that also helped a lot with leveling. The bus' bag setup looks fairly similar however much larger and more intergrated.

I guess my question is would it be as simple as capping the supply lines then diverting the bags airlines to thier own schreider valves to Fill and deflate independently?

(Yes, I searched... since November 2023. This was my first bus problem)

[flattracker]

Consider replacement of the check valves in your air ride system. I replaced one of them in the "new Crown". It used to bleed down on one side. now it stays up for extended lengths of time.

[sekkyoshi]

I will check in the AM, Thanks

[ewo1]

Having the ability to dump your air bags would be a helpful accessory to your bus. Tractor trucks have an air valve switch on the dash that will let you do that.
I would look into that type of design.

the creaking sound your rear spring makes is probably a result of the bushing either needing lube or it is in need or replacement ?

what might be cool and useful, call them broke man levelers. You could make up some arms underneath the bus that fold up when driving and release down and have the ability to lock in place and have some sort of manual length adjustment.

when you park some where, drop the arms, adjust for "level" and then dump your air bags. This would suspend the rear of the bus, keep it from side to side movement when your moving about in the bus, providing for a somewhat leveling of the bus, lean leveling that is.

just a broke man idea....

[fo4imtippin]

I replaced my leveling valve. Get under there with some soapy water in a spray bottle. It will bubble around all the fittings and hoses you need to replace. Don't put your arms or anything between any of the moving suspension components.


The cheapest option will be to repair the leaks that are there. My air stays above 70psi in my whole system for 2 weeks now. The air suspension stays erect much longer.

[s2mikon]

If you have a rear engine bus you need to make sure that the ride height is in spec. The short driveline length of these coaches will have u-joint issues if not set right. As far as an air dump, that is a great idea. Just make sure you have some type of warning to keep you from driving it when flat. I installed dump valves on mine years ago. It is nice to just dump them now instead if waiting all night or longer.

[cadillackid]

Originally Posted by s2mikon

If you have a rear engine bus you need to make sure that the ride height is in spec. The short driveline length of these coaches will have u-joint issues if not set right. As far as an air dump, that is a great idea. Just make sure you have some type of warning to keep you from driving it when flat. I installed dump valves on mine years ago. It is nice to just dump them now instead if waiting all night or longer.

ride height was a big part of me fixing the driveshaft vibe I had in my red bus... partly my carrier bearing was to blame as it needed shimmed but other part was rear driveshaft angle .. AND PINION ANGLE. on these IH air suspensions the pinion angle changes wit hthe pivot point.. on the IH this is not just an airbag asisst.. these ARE THE SPRINGS..



this is not a system that you pressurize to a certain point and forget.. if you have the system go to low on air then when you hit bumps you are slamming the suspension on bottom-out which you dont want to do..


it is designed to be a constant ride height while driving.. the levelling valve adds air if it goes low and exhausts air when it goes high.. if you add weight to the back of the bus it will automatically add pressure to maintain the ride height.


if you need to be able to dump it then you could install a relay type valve which would cut off the air supply from the tan and exhaust the air in the springs...



this suspension is not designed for keeping a bus / truck levelled while being parked.. as you walk around inside the simple bouncing up and down of the bus body will trigger the valve to release or add air from the tank until the tank is flat.. ..camping levelling should be done with levelling jacks..


another post mentioned finding leaks with a soapy water spray bottle.. YES to this.. while 5 to 8 hours to exhaust the air isnt dangerous you can probably get it better..



that said I dont worry about air being gone after a couple days.. it pumps back up on engine startup.. I am concerned if my air is leaking down to red zone in an hour or two..

[Omnibot2000]

You could plumb in a suspension dump valve typically found on highway tractors. Not that hard if all your looking for is to deflate the suspension at your resting stop.

As mentioned, soap and water. Biggest leak point I find is the height controle valve itself. Leaks at the pivot shaft that the arm is attached to and they can constantly leak out of the exhaust port of the valve itself.

[GreenPasturesCoaches]

The air bags can be replumbed just like any lowrider or hot rod system. air ride technologies has nice kits that have a computer and ride height sensors with a really nice display.

[Dbacks2k4]

A properly maintained air system should not lose any significant amount of air in weeks. That said, out of all the buses I had in my fleet over the years only one would stay above 80 PSI in the tanks after 7 days ha ha, they all eventually leak. You could go through the system with a fine tooth comb and soap water and find and repair all the leaks which would be cumbersome but best for a variety of reasons.

Alternatively, which is what I did, is put an easy drain valve on your air tanks. Its good to drain them regularly anyway to eliminate moisture (and identify oil from a failing air compressor), so when you're done driving for the day, dump the tanks. Then your air bags will deflate much more quickly since they won't be redrawing air off the tanks prolonging the issue.