Required air pressure for quad bag rear suspension

Thanks for all the input.
The tow company has begged for a 24 hour delay because of a snowstorm forecast for tomorrow. Bruce, They were going to check to see whether my 23
footer might fit on one of their flatbed trucks - and whether they would do it for the same price as "the hook".
We shall see.....
Gordon
--
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
 
We copied and implemented the external ball valve assembly in our Quadra
bag from the late Lee Harrison's 4 Bagger unit.
If you use it, it will hold the air in the bags. Now if your not
maintaining the system and letting it leake from the bags to the manifoild,
then thats your choice.
That is the main reason I implemented the 6 Ball valves on the Quadra Bag
System. If you do not take advantage of the feature, then your missing out.
We also use the all brass DOT approved air fitting to avoid leaks. (DOT is
Department Of Transportation, used on all the big rigs that haul loads
across our country.)

>
> Sorry Mike. Jim gets the banana. The handicap wheelchair ramp support
> hangs down 5 and a half inches below the frame. Been using it ever since
> 2011. And haven't riped it off yet. Came close when I hit a 200 pound pig
> on Interstate 74 in 2016. Bob Dunahugh
>
> ________________________________
> From: Bob Dunahugh
> Sent: Tuesday, February 6, 2018 6:30 PM
> To: gmclist
> Subject: RE: Required air pressure for quad bag rear suspension
>
>
> Travel hold is to allow the compressor to replace air lose while driving.
> I haven't turned my bags on to add air in them for over a year. Plus I have
> to run with my back suspension about two inches higher then GM called for.
> Don't have a choice on that. Bob Dunahugh
>
>
> ________________________________
> From: Bob Dunahugh
> Sent: Tuesday, February 6, 2018 11:42 AM
> To: gmclist
> Subject: RE: Required air pressure for quad bag rear suspension
>
>
> I've always traveled with the stock bags turned off at the bags. For the
> quad bag system now. I turn the supply line off from the compressor. The
> only time I've ever turned any bags on is when parking for the night.
> There's no reason to have the compressor line on. The burned GMC bags
> stayed up for the 19 months that it was being taken apart. Bob Dunahugh
> 78 Royale
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Finding a tilt-on flat bed that can handle s 23ft should not be hard to find. Ours was a 26ft so the bikerack had to come off and wrap the front
bumper with HD moving blankets to protect it.

The pot holes on the 401 at this time of the year will be brutal in places, especially through Toronto. Fixing a bent bogie etc ain't that cheap
either.

I'd pay extra for the roll-on.

Are you going to Borrmann's?

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Dressing the live hoses near the rotating tires will be an issue. I would install schraders and manually fill. Then follow the guy and top off if it
starts to sag.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
> Finding a tilt-on flat bed that can handle s 23ft should not be hard to find. Ours was a 26ft so the bikerack had to come off and wrap the front
> bumper with HD moving blankets to protect it.
>
> The pot holes on the 401 at this time of the year will be brutal in places, especially through Toronto. Fixing a bent bogie etc ain't that cheap
> either.
>
> I'd pay extra for the roll-on.
>
> Are you going to Borrmann's?

I'd be careful of some of the roll-on trucks. IIRC there is at lease one example of a GMC loaded on a roll-on that was to small for the job and ended
up rolling over destroying both the couch and the truck. choose carefully.
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
That was Peter Huber's coach in California which rolled on the back of a rollback. I bought some of his spare parts as the coach was totaled.
--
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
 
You could also install a regulator on the the feed from the tow truck... Probably not worth it to buy one just for this, but if you have a spare
kicking around, just plumb it inline with the tow truck's air supply....
--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
 
IIRC, that rollover was a result of operator error by truck driver.

D C "Mac" Macdonald
Amateur Radio K2GKK
Since 30 November '53
USAF and FAA, Retired
Member GMCMI & Classics
Oklahoma City, OK
"The Money Pit"
TZE166V101966
'76 ex-Palm Beach
k2gkk + hotmail dot com

________________________________
From: Gmclist on behalf of Larry
Sent: Wednesday, February 7, 2018 08:10
To: gmclist
Subject: Re: [GMCnet] Required air pressure for quad bag rear suspension

> Finding a tilt-on flat bed that can handle s 23ft should not be hard to find. Ours was a 26ft so the bikerack had to come off and wrap the front
> bumper with HD moving blankets to protect it.
>
> The pot holes on the 401 at this time of the year will be brutal in places, especially through Toronto. Fixing a bent bogie etc ain't that cheap
> either.
>
> I'd pay extra for the roll-on.
>
> Are you going to Borrmann's?

I'd be careful of some of the roll-on trucks. IIRC there is at lease one example of a GMC loaded on a roll-on that was to small for the job and ended
up rolling over destroying both the couch and the truck. choose carefully.
--
Larry
78 Royale w/500 Caddy
Menomonie, WI
 
Operator error in that the GMC should never have been put on a roll-back that is that small. Use common sense. If it doesn't look right, don't allow
it to happen. JMHO
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
What about using the onboard compressor powered by the house batteries or
from 12 volts from the tow truck?

> Operator error in that the GMC should never have been put on a roll-back
> that is that small. Use common sense. If it doesn't look right, don't allow
> it to happen. JMHO
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*
 
You guys are going through a lot of unnecessary scenarios. Do what Jim K. suggested. Air it up 2 or 3 in inches and turn off the valve. Let it set
overnight and see if it goes down. If it does leak, fix the air leak somewhere at the bags. It should hold air for months. Mine has been holding
air since last September WITHOUT shut off valves.

You are trying too get it to hold air for a day. All of this other stuff you are suggesting is totally unnecessary. Fix the leak somewhere at the
bags.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
I agree with Ken. I’ve had mine towed three times with the front lifted. 350 miles once and 200-250 miles the other two times. All times I pumped the airbags to maximum height and shut off the valves to the air bags. No damages at any time.

Emery Stora
77 Kingsley
Frederick, CO

>
> You guys are going through a lot of unnecessary scenarios. Do what Jim K. suggested. Air it up 2 or 3 in inches and turn off the valve. Let it set
> overnight and see if it goes down. If it does leak, fix the air leak somewhere at the bags. It should hold air for months. Mine has been holding
> air since last September WITHOUT shut off valves.
>
> You are trying too get it to hold air for a day. All of this other stuff you are suggesting is totally unnecessary. Fix the leak somewhere at the
> bags.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Ken Burton. Yes. You sent out what I was thinking of saying. My quad bag system never go's down. Thanks Jim K for supplying the Quad bag as it is. Bob Dunahugh 78 Royale

________________________________
From: Bob Dunahugh
Sent: Tuesday, February 6, 2018 11:42 AM
To: gmclist
Subject: RE: Required air pressure for quad bag rear suspension

I've always traveled with the stock bags turned off at the bags. For the quad bag system now. I turn the supply line off from the compressor. The only time I've ever turned any bags on is when parking for the night. There's no reason to have the compressor line on. The burned GMC bags stayed up for the 19 months that it was being taken apart. Bob Dunahugh 78 Royale
 
I guess my point is that the bags on that thing have to be much newer than my OEM bags. Jim is not in the habit of supplying junk so I assume that
the bags are OK. If not then replace the bad one.

OP never stated that they were not OK so we are down to his original request which I think is how to inflate and keep them inflated for a 400 mile
tow. I calculate that to be 8 to 12 hours. Jim K. answered that question and stated to turn off the valves after they were at the desired height.

So why not just air them up and let them sit for 12 hours or so. If they do not go down then proceed with the tow. If they do go down then air them
up again and start spraying the connections and bags with soap and find the bubbles.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Hello all,

Thanks for all the answers - but it turned out that we went the flatbed route rather than "the hook". I pumped the rear end up as high as possible
then shut off the quad bags using the valves incorporated into the system. Luckily it was a bit warmer (-18) and the rear end was only down a but 12
hours later upon arriving at Borrmann's garage. Had it been the -25 we'd had in early January the rear would have been most if not all the way down
and we might have had some difficulty getting yhe coach off the flatbed without damaging the tail pipe.

But I guess I still don't understand why (if we'd gone the hook route) 100 psi supplied to the air reservoir by a tow truck would be any different
from 100 psi coming from my Viair pump....
--
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
 
I guess that I do not understand your concern with air pressure vs. temperature change. The rule has always been a 10 degree F. temperature change =
1 PSI. In your example -18c to -25c is 7c degree temp change. Or around 12F or 13F.

So even if the temperature changed you should not have seen more than 1 or 2 PSI difference in the bags. I did all of the numbers in my head so they
are not accurate to .1 degree but they are close enough for academic discussion.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
I agree with Ken, sort of misinformation to send out.

> I guess that I do not understand your concern with air pressure vs.
> temperature change. The rule has always been a 10 degree F. temperature
> change =
> 1 PSI. In your example -18c to -25c is 7c degree temp change. Or around
> 12F or 13F.
>
> So even if the temperature changed you should not have seen more than 1 or
> 2 PSI difference in the bags. I did all of the numbers in my head so they
> are not accurate to .1 degree but they are close enough for academic
> discussion.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
No misinformation intended...and none conveyed if you take the time to read all the string carefully. New quad bag system, new Viair pump, all new
tubing and fittings, new JR Slayton control valves - all installed 12 months ago by an experienced GMC mechanic. The system will hold air for weeks
most of the year, but in very cold weather (-20C and colder), it just doesn't. Your experience may differ, but I am relating what happened out in the
driveway 5 or 6 times in a cold by historic records late December and January when I would start the engine and get the rear end up to the proper
travel level. Now of course, the air could be leaking from any number of fittings, but the "spray soapy water" diagnostic just won't work - the water
would freeze long before any bubbles appeared. My bet is on the bags. The fact that the coach lost air over the 12 hours it spent on the flatbed
with the shutoff valves closed at the rear suspension manifold (as recommended by several on this forum) tends to substantiate this conclusion.
--
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
 
OK Gordon. I was not picking on you. I just did not understand why all the concern over a 7 C temperature change.

You have an interesting problem there. It only leaks when cold below freezing. I have no ideas on the cause for that. I agree that if it leaked
when the valves are shut off, that it is probably a bag leak but I also have never worked on a 4 bag system so I do not understand the plumbing
involved.

On the soapy water idea, How about using some windshield solvent and soap mixed together? I have never tried that. Maybe that mix will not bubble.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> OK Gordon. I was not picking on you. I just did not understand why all the concern over a 7 C temperature change.
>
> You have an interesting problem there. It only leaks when cold below freezing. I have no ideas on the cause for that. I agree that if it leaked
> when the valves are shut off, that it is probably a bag leak but I also have never worked on a 4 bag system so I do not understand the plumbing
> involved.
>
> On the soapy water idea, How about using some windshield solvent and soap mixed together? I have never tried that. Maybe that mix will not bubble.
>

My left front tire will hold air all year. Except during the very cold
days of winter. Then it will go flat. Have never found leaks with water
and bubbles.

--
Gary W. Mills
Livonia, MI
. ___________
./_][__][] []| 1974 GMC M/H
.*O-------OO-* Painted Desert
 
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