Air bag pressure

bob horton

New member
Dec 30, 2005
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What is the normal pressure in the airbags??? How much pressure will they take??? I installed a VIAIR compressor with a 125 PSI shut off. Hope I don't blow the airbags to smithereens. Presently installing Jim B's shut off kit. (One side done - so far so good) (Wish these darn jackhooks provided a bit more clearance for the jack.) Once I can isolate the airbags I will be installing JR's new valves. Wish me luck.

Also put in the bogey greasers. Wish everything was that easy. Next will be a Duromax. Only 70,000 plus you say??? Guess I will have to wait for my lottery numbers come in on that one.

Bob Horton (75 Glenbrook)
Brandon, Manitoba

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> What is the normal pressure in the airbags??? How much pressure will they take??? I installed a VIAIR compressor with a 125 PSI shut off. Hope I don't blow the airbags to smithereens. Presently installing Jim B's shut off kit. (One side done - so far so good) (Wish these darn jackhooks provided a bit more clearance for the jack.) Once I can isolate the airbags I will be installing JR's new valves. Wish me luck.
>
>
> Bob Horton (75 Glenbrook)
> Brandon, Manitoba


My airbags generally run about 90 PSI as I recall. My compressor will bring them up to about 120 psi at full raise position. No problems.

Bob Rosenberg's jack hook is built with enough clearance to use a normal bottle jack under it. Not all have that advantage. Be sure to let the bags down and use a bogey support metal piece when you are jacking. Makes it a whole lot easier.

And I am one who does not want the air bag shut off valves, although many love them. Mine cracked, leaked and in general were a PITA. If you have good dash valves, and good tubes, you don't need any extra shut off valves. Just have an emergency schrader valve you can put in if you develop some serious tubing leak.

JR's valves are wonderful.

--
Rob Allen
'76 x-PB

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> > What is the normal pressure in the airbags Bob Horton (75 Glenbrook)
> > Brandon, Manitoba
>
> My airbags generally run about 90 PSI as I recall. My compressor will bring them up to about 120 psi at full raise position. No problems.
> have an emergency schrader valve you can put in if you develop some serious tubing leak.
> JR's valves are wonderful.

The Viair is a great choice, powerful and relatively quiet.
It would be a good idea to take the bags and fittings all apart and fit the Schrader valves before that 'rainy night in JawJaw' with parts all over the ground next to the road.
"remind me, too"

--
Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC

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I typically run my bags at about 90 - 95 lbs.

Ray Erspamer
78 Royale - Malosco Cruiser (TZE368V101144)
2202 N 115th St
Wauwatosa, Wisconsin 53226
78GMC-Royale
414-745-3188
Web Site: http://www.angelfire.com/planet/raysgmc/

----- Original Message ----
From: Hardie Johnson
To: gmclist
Sent: Tuesday, July 3, 2007 8:58:14 AM
Subject: Re:[gmclist] Air bag pressure

> > What is the normal pressure in the airbags Bob Horton (75 Glenbrook)
> > Brandon, Manitoba
>
> My airbags generally run about 90 PSI as I recall. My compressor will bring them up to about 120 psi at full raise position. No problems.
> have an emergency schrader valve you can put in if you develop some serious tubing leak.
> JR's valves are wonderful.

The Viair is a great choice, powerful and relatively quiet.
It would be a good idea to take the bags and fittings all apart and fit the Schrader valves before that 'rainy night in JawJaw' with parts all over the ground next to the road.
"remind me, too"

--
Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC

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A couple of weeks ago, we were driving up I-75 at the Tennessee-Kentucky border when the coach began listing to the right. Turned out it had developed a leak in the air line and gradually de-pressurized. Pulled off to the shoulder to make sure we hadn't lost the bag (we carry a Ragusa "dog bone" plus a spare bag just in case), then lowered the left side and limped for about five miles to the next exit. Threaded in a Schrader, filled it with shop air from a local auto repair garage, and were on our way (fixed the leak after we returned home).

Rob speaks from experience, and I agree, that shut-off valves are just another thing that can go wrong. Sure it might be tough to thread in the valves "on the side of the highway in a driving rain storm at 2 am", but frankly I never drive my coach at 2 am, so it's really not an issue for me. The one item I'd like to address, however, is the ability to access the compressor while bypassing the system, doing away with the need for an external air source. Does anyone know how to go about attaching a quick-connect fitting to the Dana (i.e. where to attach it)?
--
Nick Chapekis
Ypsilanti, MI
78 Kingsley

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Bob Horton writes...

> What is the normal pressure in the airbags???

It depends on the weight of your coach. 90-95 sounds about right for a
typically heavy coach. Mine is light and probably only has 80 in the
bags and proper ride height.

> How much pressure will they take???

More than the Viair pump can deliver without burning up. 150 psi is no
problem at all. I have routinely aired my bags to 125 psi to maximize
ground clearance without issue.

> Presently installing Jim B's shut off kit.

The cut-off valves are a good, sensible thing for a new owner to do.
Make it so you can fill the bags with shop air and use the coach. I
did the same. But as I started going through my air suspension system,
I discovered that there is a continuous, unbroken hose from the bag to
the dashboard control valves. When in Hold, the dash valves are
pnuematically identical to cut-off valves, with the sole exception of
the long run of hose.

But that long run of hose has been subject to a lot of damage over the
years, and often has been cut and spliced as other work has been done.
So, go to McMaster-Carr, search on "DOT Nylon Tubing" and buy a roll
of it. Then, replace the runs from the bags to the control valves, and
do it when you install J.R.'s control valves. When you do that, you
can remove the cut-off valves.

I still have a leak in my right bag, but I can remove the hose and
replace it with a Shrader valve, fill it up, and it will still leak.
The leak is not in the bag, but in the fitting that screws into the
bag. There's an O-ring in there that is easy to damage if the big nut
binds, and I've already replace it once. Next time I have the bag out,
I'm epoxying that fitting in there. The point is, though, that even
cut-off valves don't preclude all possible leaks.

You might find this article helpful:

http://www.gmceast.com/Power%20Level%20System%20watermark.pdf

Rick "who also had a cut-off valve that leaked" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

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For years we had a filler valve threaded into one of the spare threaded
holes in the air tank under the fender for this use. When I bought new
ss tank from our friend in Canada though I never put it back in as the
orignal 30 year old one was leaky itself. But a good reminder to add it
for quick fill if needed. thanks

> ................ The one item I'd like to address, however, is the ability to access the compressor while bypassing the system, doing away with the need for an external air source. Does anyone know how to go about attaching a quick-connect fitting to the Dana (i.e. where to attach it)?
>
.

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> Nick Chapekis wrote

>Does anyone know how to go
> about attaching a quick-connect fitting to the Dana (i.e. where
> to attach it)?

I plumbed a couple of shop style quick disconnect from the air tank on my 1973 GMC. One under the hood near the drivers head light and one behind the back bumper of the coach.

I carry 25 feet of 1/4" hose as well as an air chuck so I could not only pump up an air bag but also can air up a tire on the road should I need to.

Other than issues of convenience it would work just as well plumbed directly onto the air tank.

On my coach I've got 2 small air pumps (department of redundancy department) and tested the feasability of the air supply by breaking the bead on a GMC tire and wheel. with the aid of a ratchet strap around the tread on the tire I was able to seat the tire using only my "onboard" air supply. So the rig should have enough air for anything I want to do on the road.

Hope this helps.

Regards

Gary Zingle
1973 GMC 26 foot "Paradise"
Edmonton, Alberta, Canada

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George, Your doing it right. Air pressure does no relate directly to
correct height.
At our shop we use a stick with the correct height to check.

>
>
> Before starting a trip,I adjust my air bags to the correct ride height, sitting flat with a normal load of passengers, water and gas.
> --
> geo groth '73 260 Sequoia
> Carson City Nevada
>
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--
Jim Kanomata
Applied/GMC
jimk
1-800-752-7502

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What length stick do you use Jim??

Ray Erspamer
78 Royale - Malosco Cruiser (TZE368V101144)
2202 N 115th St
Wauwatosa, Wisconsin 53226
78GMC-Royale
414-745-3188
Web Site: http://www.angelfire.com/planet/raysgmc/

----- Original Message ----
From: Jim Kanomata
To: gmclist
Sent: Tuesday, July 3, 2007 12:20:18 PM
Subject: Re: [gmclist] Air bag pressure

George, Your doing it right. Air pressure does no relate directly to
correct height.
At our shop we use a stick with the correct height to check.

>
>
> Before starting a trip,I adjust my air bags to the correct ride height, sitting flat with a normal load of passengers, water and gas.
> --
> geo groth '73 260 Sequoia
> Carson City Nevada
>
> To unsubscribe or change your settings - http://www.gmcnet.org/settings.htm
> Donate to support GMCnet - http://www.gmcnet.org/support.html
>

--
Jim Kanomata
Applied/GMC
jimk
1-800-752-7502

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> George, Your doing it right. Air pressure does no relate directly to correct height. At our shop we use a stick with the correct height to check.
> Quote:

> > > Before starting a trip,I adjust my air bags to the correct ride height, sitting flat with a normal load of passengers, water and gas.
> > > --
> > > geo groth '73 260 Sequoia
> > > Carson City Nevada
>
> --
> Jim Kanomata
> Applied/GMC
> jimk
> 1-800-752-7502

Yabbut, flat is not exactly right, if you mean level floor. The coach should sit slightly tail-dragger. You can set the stick to measure at the beltline or taillight, but check the front bumper, too.
"not to self, make a new stick to replace the one left in Enola"

--
Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC

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Jim

Would you post that measurement? Was it 32 1/4"??? I can't remember exactly.

john harper
whose got the day free because someone else is working for him ( thank
god!!)

----- Original Message -----
From: "Jim Kanomata"
.
> At our shop we use a stick with the correct height to check.--
> Jim Kanomata
> Applied/GMC
> jimk
> 1-800-752-7502
>

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> What length stick do you use Jim??
> Ray Erspamer
> 78 Royale - Malosco Cruiser (TZE368V101144)
> 2202 N 115th St
> Wauwatosa, Wisconsin 53226
> 78GMC-Royale
> 414-745-3188
> Web Site: http://www.angelfire.com/planet/raysgmc/

I am not Jim, but you make the stick when you setup ride height on the coach. Mark the front, too. The front may change under load, but if the suspension is working right, theoretically, the rear is self adjusting. Check both sides.
"theory vs practice'
--
Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC

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> The one item I'd like to address, however, is the ability to access the compressor while bypassing the system, doing away with the need for an external air source. Does anyone know how to go about attaching a quick-connect fitting to the Dana (i.e. where to attach it)?

Not to the pump, but to the tank. I replaced the bottom drain with a street 90* and a brass ball valve. I attached a male adapter for my shop air hose to the outlet of the valve. I carry a hose long enough to get to the left rear tire. It has female shut off fittings at both ends and I can plug in a variety of things, even an air wrench. That matches my shop hose system.
The ball valve also encourages frequent draining of the tank to dump moisture. Total cost was about $20.
"in with the good air, out with the bad"
--
Hardie Johnson "Crashj"
1973 26 foot Glacier, White Thing
Raleigh NC

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> Not to the pump, but to the tank.


That'll be easy enough. Once I access the air, though, how do I run the pump independent of the system? For example, after I developed the leak in the air line, I could not run the pump on travel because the air just escaped through the leak in the line. All I could do was set it on hold and use the pump to inflate the good side.
--
Nick Chapekis
Ypsilanti, MI
78 Kingsley

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> > The one item I'd like to address, however, is the ability to access the compressor while bypassing the system, doing away with the need for an external air source. Does anyone know how to go about attaching a quick-connect fitting to the Dana (i.e. where to attach it)?
>
> Not to the pump, but to the tank. I replaced the bottom drain with a street 90* and a brass ball valve. I attached a male adapter for my shop air hose to the outlet of the valve. I carry a hose long enough to get to the left rear tire. It has female shut off fittings at both ends and I can plug in a variety of things, even an air wrench. That matches my shop hose system.
> The ball valve also encourages frequent draining of the tank to dump moisture. Total cost was about $20.
> "in with the good air, out with the bad"


That is exactly the same solution that I used. Sure makes for easy and quick draining of the tank. I installed but have never it needed the schrader at the tank.

I too am against the use of the shut off valves and any excess hardware mounted on the bag itself. There is continuous vibration and bouncing applied to the assembly while going down the road.

It ain't fun fixing a damaged shut off and it's associated plumbing off valve one at the side of the road. Do not forget to carry an easy out to get out the broken piece of pipe from the air bag.

It only takes a few minutes to screw in a spare schrader valve if it is ever needed. Also carrying a spare schrader(s) does not take up much room or weight in the coach. Forget the shutoffs and carry 2 spare schraders. You will probably never need either.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Is it a good idea to tap off of the bottom of the tank? Won't you get all of the moisture that collects there?

Ray Erspamer
78 Royale - Malosco Cruiser (TZE368V101144)
2202 N 115th St
Wauwatosa, Wisconsin 53226
78GMC-Royale
414-745-3188
Web Site: http://www.angelfire.com/planet/raysgmc/

----- Original Message ----
From: Nick Chapekis
To: gmclist
Sent: Tuesday, July 3, 2007 1:18:11 PM
Subject: Re:[gmclist] Air bag pressure

> Not to the pump, but to the tank.

That'll be easy enough. Once I access the air, though, how do I run the pump independent of the system? For example, after I developed the leak in the air line, I could not run the pump on travel because the air just escaped through the leak in the line. All I could do was set it on hold and use the pump to inflate the good side.
--
Nick Chapekis
Ypsilanti, MI
78 Kingsley

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Since the instruction calls for measuring from the top of the slot to
th ground, we did a simple measurment and cut. Rear is about 8 1/2 "
long, front about 9 1/2"

>
>

> > George, Your doing it right. Air pressure does no relate directly to correct height. At our shop we use a stick with the correct height to check.
> > Quote:

> > > > Before starting a trip,I adjust my air bags to the correct ride height, sitting flat with a normal load of passengers, water and gas.
> > > > --
> > > > geo groth '73 260 Sequoia
> > > > Carson City Nevada
> >
> > --
> > Jim Kanomata
> > Applied/GMC
> > jimk
> > 1-800-752-7502
>
> Yabbut, flat is not exactly right, if you mean level floor. The coach should sit slightly tail-dragger. You can set the stick to measure at the beltline or taillight, but check the front bumper, too.
> "not to self, make a new stick to replace the one left in Enola"
>
> --
> Hardie Johnson "Crashj"
> 1973 26 foot Glacier, White Thing
> Raleigh NC
>
> To unsubscribe or change your settings - http://www.gmcnet.org/settings.htm
> Donate to support GMCnet - http://www.gmcnet.org/support.html
>

--
Jim Kanomata
Applied/GMC
jimk
1-800-752-7502

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