* you are running with your bags on a shut-off, (pix stolen from Kelvin)

  * you use schrader valves to fill your air bags

*  no need to discuss if this works --- you are already there !

*  Your coach leaks down - all the time
*  Need to rebuild / replace your air pump
*  Need to replace the air hoses
*  Valves running to the front - all over the GMC?
*  Tired of not being able to level your coach ?
*  Have 2 air pumps to replace?

by Ken Peterson
*   No longer care if  you are Power Level, EL I , or EL II system
*   Remove all the air lines - except one to each air bag system
*  No leveling valves
*  No  running valves, switches, etc
*  Only one  air pump, ( back by the bags)

Here is a link to a pic of my wireless air system test bench and latest wireless air system that I built.
  In the pic you will see the system is setting on a test bench that I also built so I can determine that the wireless air system is leak free and that the digital remote controller is functioning properly.  I use the test bench to test each wireless air system to be sure the air system is leak free and that all the electronics are functioning properly


I found it to be fairly expensive to have the aluminum frame built like my original one.  After doing some looking around I remembered seeing pictures of what Ray Erspamer air setup when he redid his air system some time ago. I contacted him and he said he used UHMW plastic material and it has held up great.  So I ordered some and built the frame using it instead of aluminum. Works great.  Easy to work with.  You can cut it with a table saw.  Drills easily.  That solves a problem for someone trying to figure out what to use to build a frame.  It looks great when you are done.

1 The wireless kit in the pic is different than the one I installed on my coach 15 months ago.  Same part number, but new an improved.
The digital remote has a number of icons that mine does not have such as low battery, leak detected, fail indicator for valve blockage or communication failure and more.

2 The two(2) connections on the digital manifold are the easy slip in style instead of the old style connector that you had to use a wrench to tighten like mine.

3 The new wireless air system comes with the digital remote mated with the digital manifold.  No more having to tough the two together on setup to try and get them to recognize each other.

4 There are now only two (2) wire to hook-up to the coach with this setup as compared to three (3) my old one.   One wire goes to ground and the other to the ignition switch.

Those are the main difference.  Not a lot, but a few.
Gary Bovee


There are lots, and lots of GMCs that do not have working air-leveling systems,  and have to run on schrader valves, and shutoffs (at the risk of death due to exploding air bags;>).

the wireless air system used by  Shotwell, and Bovee, allow you to remove all of the OEM air system, and simply connect a single hose to each bag, and adjust the height of your GMC 

This system has been presented on GMC coaches on bothe coasts.
this system is very easy to install and use, and will keep you from sticking your head in beside the explosive air bags, and shutoff valves.  . geneF

The system is designed as an automatic leveling system.  If it senses air pressure gain or loss of more than 3 pounds difference than the setting you have programed into the wireless digital remote controller for each bag, it will automatically readjusts the air pressure in each bag back to the programed setting when the ignition key is turned on.

This particular system was not designed to be used with leveling control valves. Gary Bovee




We have a late '78 Royale Center Kitchen with the EL II system. The air lines had been pretty well butchered by some PO, and one of the leveling sensor links was missing. Also, there were two airlines in the driver’s side wheel well that were not connected to anything. Only one of the two compressors worked (sorta). We, like a lot of GMC owners, always used Schrader valves and shutoffs to pump up the air bags.

I recently redid the complete rear braking system, and while back there, decided it was a good time to get the EL II system working.

I had four extra junk yard compressors that were in a box that came with the coach. None of them worked very well, and one got real hot and smelled ‘electrical’. So out of the total of six pumps I had to work with, none were very good.

And, only one of the two optical height sensors actually worked. The bad one wouldn't shut off a compressor at all. I also found that one of the 1/4" air lines that traverses the body had a flat spot in it, just like when you put a penny on the railroad track to flatten it. Probably happened when all but four of the 22 body-to-frame isolator pads fell out over the years. Those pads have since been replaced.

So, decision time. Do we keep beating a 32 year old dead horse, or look at alternatives to get this coach pumped up to where it should be. I researched the net and found a couple of interesting items. One was a system for trucks (?) that used magnets and magnetic sensors on the frame - you put something heavy in the bed, and the little compressor pumps up the air springs (our air bags) to bring it level again. Great! But the system fed both sides of the vehicle at the same time - not good for our coaches, because we may want to have different pressures in each air bag.

Then I found what we ended up getting and installing. A system that would put different pressures in each air bag, and control those pressures automatically. But it lacked the automatic leveling feature, as the above system had. Figuring that it was more important to be able to air up each bag by itself, this system would work better for our coach.

The AirLift 72000 Wireless Leveling Control System

This new system consists of one small compressor, a 'module', a relay, 25' of 1/4" DOT tubing, wiring harnesses, and all the hardware you could want. It hooks up to a 12v, on-all-the-time lead, a 12v, ignition switched lead, and a ground. You run an air line from the compressor to the module, and two air lines from the module, one to each of the air bags. That’s it. Simple.

The cool part is that it includes a remote control, about the size of a garage door opener, that controls the whole system - even from outside the coach. You can control the pressure in each bag individually and set the pressures up to 100 psi in each bag. It has a dump feature to let the air out of the bags. So, if you put in 40 gallons of water, and now your right side is down an inch, hit the remote and increase the pressure in the right air bag to bring the coach up to correct ride height. Again, simple.

I cut a 1 x 1 to the correct length to fit right under the front zerk on the bogies. I can stand outside the coach with the remote in hand and adjust the air pressures so the stick just fits under the zerk. I made the stick length based on the correct ride height for the rear by the holes in the frame. The remote also has two 'preset' buttons - I keep the pressures in the 1st button for road travel, and the 2nd button for the current campsite we’re in. When we leave the campground, we hit the #1 button and we get right up to the correct height for the road. Still simple.

If we’re going into somewhere that might cause the coach to scrape its rear end, you can hit the ‘up’ arrow and the compressor will pump both bags up 10 lbs each. Hit it again, and they both go up another 10#. Also, there’s a ‘down’ arrow that will dump 10 lbs from both bags each time you hit it.

The system will increase or decrease the pressure in each bag automatically to what you have each bag pressure set to, whenever the key is on. Also, the remote control will not let either bag go above 100#.

Because our coach is a center kitchen, the two old compressors were in a cabinet in the rear section, behind the bath. I just replaced both of those with a new Viair 275C that I had on hand. The compressor that comes with the new system (also a Viair) puts out a little over 1.0 cfm, and the 275C puts out 2.03 cfm. I used the 275C because I had it. I have no doubt that the included compressor will handle keeping the bags pumped up; it was designed for the system (unless you have a susbstantial leak, at which point you should tackle that problem first, anyway). Also, as the EL II original setup didn’t use an air tank, we don’t use one either.

During the install, the remote control has to be ‘joined’ to the module. That’s to keep your campground neighbor from messin’ with your pressures in the middle of the night with his remote. Your remote will only control your system. I used some of the old wiring from the original EL II system, as it was already there from the original pumps.

This system might not be for everyone, or if you're trying to stay authentic, but we sure like it.

Here's a link:

   --  John Shotwell

Bob Burkitt was kind enough to point me in the direction to contact John Shotwell who had installed the Air Lift #72000 system. 
I got info from John and then modified the system to my liking.

I have been trying for sometime to figure out what to do with my original air system on my 1978 Royale that the PO had modified trying to upgrade it from and EL-1 to an EL-II system. When I got the coach all the wires going to the compressor and wires from the height control valve had been cut off by the compressor. Since I am an electrically challenged one I new I had a real mess on my hands. But, thanks to those of you who responded to my air system questions a couple of months ago I found a solution that works for me. Particularly, big thanks to Bob Burkitt and John Shotwell for their input.

What I ended up doing is installing a wireless air system. All I needed to do was figure out which wire was the hot wire from the battery, ground wire and ignition wire in the mess of over a dozen cut off wires that were laying by my old compressor. Even the electrically challenged one was able to figure it.

So now I have an air system that I can control my Quadra Bag System with a remote control that is about the size of a pack of cigarettes. It has two programs that I can set whether I am running heavily loaded or a light load. I can raise or lower each side's air bags independently of the other or both at the same time. When I am finished dry camping and have previously raised or lower one side or the other I can press program I or II whatever I need and the coach rear ride height readjusts to height I have set for travel. I can even stand outside of the coach and raise or lower the rear of the coach with the remote.

It is nice to finally have the air system working so that I don't have to use my plug-in compressor to manually air up the bags.  I can now travel with the air bag valves open. If I were to loose any air the system automatically comes on and readjusts to the programed air pressure setting Ihave it set to. If the air system compressor were to fail I have it set-up so that I can still manually fill the bags with my old plug-in compressor. Gary Bovee - 8-20-10

Here is a link to my pics -

Bovee’s Wireless Air System

1.    How Did I Decide On It?

The original air system in our coach was not functional. The PO made numerous modifications and had cut off all the wires at the air system never finishing the project. I had no clue where to start.   So I decided to start from scratch.  I did my homework and found a GMCer (John Shotwell) from the Eastern States Club that had installed a wireless air system.  I studied his setup and then made a couple tweaks of my own (added ss air pressure tank & water trap).

How does the System Work?

2.    This is a pressure based system.  It uses no leveling valves. If you are running only on Schrader valves, then it will be basically the same concept EXCEPT:
    a.    No more having to go to the bags to fill or release air;
    b.    No more having to drag out a compressor to air up your bags for travel.
    c.    You program the remote digital controller for the proper ride height and it will automatically keep the bag’s air pressure within plus or minus 3 pounds of the programmed setting for each bag.
    d.   The nice thing is – when you park at an RV park or are dry camping you use the remote to level your coach.
    e.    When you are ready to hit the road you just push the programmed button for road travel. It adds or releases air, whatever is needed for each bag and you are soon on your way.  (This system has a             maximum air pressure limit of 100 pound.)

3.    Where is the system located?
The system in my Royale is located under the driver’s side bed. You could locate it just about anywhere you want that has enough room for the system.  The system only needs three wires to hook it up: One wire from the ignition switch, one hot wire and one ground wire. It could be used on any of the GMC models to replace the original air system.

4.    My Wireless Air System Components:
    a.    Viair Compressor  - # 450c Applied GMC
    b.    Norgren - Water Trap - F07 Applied GMC
    c.   Stainless Steel Pressure Tank - #104 Applied GMC
    d.    40 Amp Relay – Applied GMC
    e.    Air Lift Kit - #72000 – Applied GMC
          * The Wireless Air System has a built in function that will automatically shuts off the compressor if it tries to run continuously longer than 3 minutes.  It will then shut off for 7 minutes before becoming operational again.  It will work on an off like this until the bags are filled to the pressure you have set in the wireless digital controller.  This is the problem of using a compressor that is too small and can't fill the bags in less than 3 minutes. 

If you are going to be using the Wireless Air System to level your coach when parked, I recommend using a compressor that has a 100% duty cycle rating unless you don’t mind waiting 7 minutes between shutdowns.

If you are only going to be using the Wireless Air System to keep your bags within plus or minus 3 pounds of the settings for the bags you have programed in the wireless digital controller a smaller compressor will work just fine

5.    Costs:   
    a.    Viair Compressor - $249.00.
    b.    Water Trap - $19.00. Technical support at Air Lift suggests that you should use a water trap with the air system being used in this manner.
    c.    Stainless Steel Air Pressure Tank - $89.95 - Technical support at Air Lift suggests that you should use an air tank with the air system being used in this manner.
    d.    Relay – $7.95 -
    e. Air Lift Kit - $380.00


Gary Bovee

Jim K. at Applied GMC can supply the wireless kit for , Viair 450c compressor $249,  ss tank 89.95, and water trap for $19. He can supply everything you will need -Bovee 5-12-11



Airlift instruction manual   down load