Required air pressure for quad bag rear suspension

G

gordon gibson

New member
Oct 3, 2012
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Hello Group

I will shortly be having my coach towed (front wheels lifted of course) approximately 400 miles. Not sure the air bags will fully hold their pressure
this distance (even less likely in -20C weather), and I don't want the rear end to be dragging by the end of the trip. I also don't want to have to
periodically start the engine to run on-board compressor. The tow truck can provide compressed air and I have a quick disconnect valve on my air
pressure tank. so I was thinking of simply connecting the trucks compressed air line to the tank,

Does anybody know the appropriate PSI to feed the tank given that the rear suspension is one of the Bounds / Applied GMC quad bag systems?

Thanks

Gordon

PS - I trust that if this is a dumb approach someone will let me know in no uncertain terms, along with why....
--
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
 
System pressure in my GMC is 130 psi. Everythings holds and have 90-100 psi in the air bags. System pressure in my dump truck (for air brakes, made
with a real engine-driven compressor) is 175 psi. I don't think the system in the GMC will tolerate that pressure and might rupture or pop the air
line connections apart or go past the check valves in the little compressor. Use a regulator between the two vehicles and then you will be OK.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
It is not the pressure but the height. Raise it about 2-3. Inch higher and
lock the valves that are. Part of the bags

On Tue, Feb 6, 2018 at 7:34 AM Gordon Gibson
wrote:

> Hello Group
>
> I will shortly be having my coach towed (front wheels lifted of course)
> approximately 400 miles. Not sure the air bags will fully hold their
> pressure
> this distance (even less likely in -20C weather), and I don't want the
> rear end to be dragging by the end of the trip. I also don't want to have to
> periodically start the engine to run on-board compressor. The tow truck
> can provide compressed air and I have a quick disconnect valve on my air
> pressure tank. so I was thinking of simply connecting the trucks
> compressed air line to the tank,
>
> Does anybody know the appropriate PSI to feed the tank given that the rear
> suspension is one of the Bounds / Applied GMC quad bag systems?
>
> Thanks
>
> Gordon
>
> PS - I trust that if this is a dumb approach someone will let me know in
> no uncertain terms, along with why....
> --
> Gordon Gibson
> 1976 23" Norris Upfit
> Montreal West, Quebec, Canada
>
> _______________________________________________
> 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
 
Thanks Terry. I was planning to ask the tower to regulate for 100 PSI, so your response confirms I'm in the ballpark.
--
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
 
You've probably made final arrangements for transportation, but if you have not, consider this kind of transportation for your coach.

http://www.gmcmhphotos.com/photos/our-coach/p56437-towing-our-coach.html
http://www.gmcmhphotos.com/photos/our-coach/p56438-towing-our-coach.html

I think it is called a "flatbed landau". Guys...correct me if I'm wrong.

I have towed my coach twice this way and seems to me to be the safest way, and did not cost that much more. "On the Hook" can be very hard on rear
suspension parts. If you raise the rear to high to keep the tail from dragging, you risk breaking in some way the shock absorbers or their mounts.
Tow low and you scrape the tail. Both adjustments for travel on the hook go to the extreme while bouncing around going down the road. Short distances
going slow, the "Hook" which I include lifting the front wheels, can work IF you have a conscientious driver...at times hard to find. JMHO
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
Jim,

I get the part about raising the rear a couple of inches. But if I lock the valve, doesn't that mean that as well as not escaping, air won't be able
to get into the bags as well? They generally hold air well, and the compressor only comes on once or twice during a normal day's driving. But in the
extreme cold, the rear will start to drop an hour or two after shutting the engine off. My guess is that the slow leak in very cold weather is coming
from the bags rather than the tubing and fittings because they lose elasticity as things freeze up.

Gordon
--
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
 
Larry
I definitely hear you and would much prefer this approach, but the rate quoted for a Landoll is about twice that for "the hook". Even if I eend up
having to replace 4 KYBs the hook is hundreds of $$ cheaper. Hopefully the saving grace is that the tow will all be on smooth 3-lane highway.
Gordon
--
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
 
Raise the rear to maximum suspension travel, and turn the supply air valve
off. Have the tow driver only raise the front wheels enough to give
clearance for road crowns, etc. The one time I was towed was from SeaTac to
Tacoma southbound on interstate 5 at 70 mph. No problems at all. My Royale
has stock EL II rear suspension. Your quad bag setup should not be any
problem towed this way. Unless, you have stuff hanging under the rear of
the coach that the factory didn't put there.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Larry
> I definitely hear you and would much prefer this approach, but the rate
> quoted for a Landoll is about twice that for "the hook". Even if I eend up
> having to replace 4 KYBs the hook is hundreds of $$ cheaper. Hopefully the
> saving grace is that the tow will all be on smooth 3-lane highway.
> Gordon
> --
> Gordon Gibson
> 1976 23" Norris Upfit
> Montreal West, Quebec, Canada
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> Larry
> I definitely hear you and would much prefer this approach, but the rate quoted for a Landoll is about twice that for "the hook". Even if I eend
> up having to replace 4 KYBs the hook is hundreds of $$ cheaper. Hopefully the saving grace is that the tow will all be on smooth 3-lane highway.
> Gordon

Gordon,
I all fairness, I was lucky enought to have good towing insurance and a tow company 1 1/2 miles from my home. Lots of people have done it front wheels
up with no issues. Will be thinking of you. With the rest of the advise you get here, pretty sure your tow will go well.
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
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
 
Gordon,

http://www.gmceast.com/technical/Mueller_GMC-Towing-Guide.pdf

As far as driving a GMC with the bags turned off I wonder why the guys that designed the system instruct owners to put the system in
the "Travel" setting?

In the "Travel" setting the system controls the air pressure to the bags.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Gordon Gibson
Sent: Wednesday, February 7, 2018 2:11 AM
To: gmclist
Subject: [GMCnet] Required air pressure for quad bag rear suspension

Hello Group

I will shortly be having my coach towed (front wheels lifted of course) approximately 400 miles. Not sure the air bags will fully
hold their pressure this distance (even less likely in -20C weather), and I don't want the rear end to be dragging by the end of the
trip. I also don't want to have to periodically start the engine to run on-board compressor. The tow truck can provide compressed
air and I have a quick disconnect valve on my air pressure tank. so I was thinking of simply connecting the trucks compressed air
line to the tank,
Does anybody know the appropriate PSI to feed the tank given that the rear suspension is one of the Bounds / Applied GMC quad bag
systems?

Thanks
Gordon

PS - I trust that if this is a dumb approach someone will let me know in no uncertain terms, along with why.
 
"Travel-Hold" maintains pressure that the height controls determine from
measuring the suspension position. Requires ignition to be in the "on" or
"acc" position. If you want the suspension to be at the fully extended "up"
position for clearance while towing, I don't think "ride height" is what
you want..
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Gordon,
>

>
> http://www.gmceast.com/technical/Mueller_GMC-Towing-Guide.pdf
>
> As far as driving a GMC with the bags turned off I wonder why the guys
> that designed the system instruct owners to put the system in
> the "Travel" setting?
>
> In the "Travel" setting the system controls the air pressure to the bags.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces] On Behalf Of
> Gordon Gibson
> Sent: Wednesday, February 7, 2018 2:11 AM
> To: gmclist
> Subject: [GMCnet] Required air pressure for quad bag rear suspension
>
> Hello Group
>
> I will shortly be having my coach towed (front wheels lifted of course)
> approximately 400 miles. Not sure the air bags will fully
> hold their pressure this distance (even less likely in -20C weather), and
> I don't want the rear end to be dragging by the end of the
> trip. I also don't want to have to periodically start the engine to run
> on-board compressor. The tow truck can provide compressed
> air and I have a quick disconnect valve on my air pressure tank. so I was
> thinking of simply connecting the trucks compressed air
> line to the tank,
> Does anybody know the appropriate PSI to feed the tank given that the rear
> suspension is one of the Bounds / Applied GMC quad bag
> systems?
>
> Thanks
> Gordon
>
> PS - I trust that if this is a dumb approach someone will let me know in
> no uncertain terms, along with why.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I recently had my coach towed 169 miles on a front wheel lift. I maxed out my Quadra Bag system at 140 psi, which is the cut off for my compressor,
then isolated the bags at the manifolds in the wheel well (part of the Quadra Bag system). There were no issues with the tow. If I had put the air
valves in "travel" the rear end would have been too low.

I don't know what effect the extreme cold will have on the bags, but if the tow truck driver can regulate the system to 130 psi, and tie into your air
system, that should certainly keep your air bags full for the trip.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
G'day,

I apologize; obviously my previous email was not clear.

http://www.gmceast.com/technical/Mueller_GMC-Towing-Guide.pdf

Step 16 of my procedure states:

16. Before the GMC is raised by the front wheels or put on a trailer, raise the rear suspension
to the maximum height and place the system in HOLD. This is to greatly reduce the
likelihood of the rear dragging at some point in the process.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of James Hupy
Sent: Wednesday, February 7, 2018 8:52 AM
To: gmclist
Subject: Re: [GMCnet] Required air pressure for quad bag rear suspension

"Travel-Hold" maintains pressure that the height controls determine from
measuring the suspension position. Requires ignition to be in the "on" or
"acc" position. If you want the suspension to be at the fully extended "up"
position for clearance while towing, I don't think "ride height" is what
you want..
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Gordon,
>

>
> http://www.gmceast.com/technical/Mueller_GMC-Towing-Guide.pdf
>
> As far as driving a GMC with the bags turned off I wonder why the guys
> that designed the system instruct owners to put the system in
> the "Travel" setting?
>
> In the "Travel" setting the system controls the air pressure to the bags.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces] On Behalf Of
> Gordon Gibson
> Sent: Wednesday, February 7, 2018 2:11 AM
> To: gmclist
> Subject: [GMCnet] Required air pressure for quad bag rear suspension
>
> Hello Group
>
> I will shortly be having my coach towed (front wheels lifted of course)
> approximately 400 miles. Not sure the air bags will fully
> hold their pressure this distance (even less likely in -20C weather), and
> I don't want the rear end to be dragging by the end of the
> trip. I also don't want to have to periodically start the engine to run
> on-board compressor. The tow truck can provide compressed
> air and I have a quick disconnect valve on my air pressure tank. so I was
> thinking of simply connecting the trucks compressed air
> line to the tank,
> Does anybody know the appropriate PSI to feed the tank given that the rear
> suspension is one of the Bounds / Applied GMC quad bag
> systems?
>
> Thanks
> Gordon
>
> PS - I trust that if this is a dumb approach someone will let me know in
> no uncertain terms, along with why.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Gordon,
We had our 77 Palm Beach brought back from Quebec City to Stratford ON (about an hour to Borrmanns). It was on a single axle flat bed roll on truck.
We had about 2" under his length limits. He had no issues with weight or height.

The tow company was from the east side of Montreal. I could dig up their info if you like. Certainly would be easier on the coach riding back than
getting dragged 400 miles.
--
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
 
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
 
Hey Bob D.:
Why do you "have" to run w/ rear 2" higher? Just curious!
Mike/The Corvair a holic
And don't tell me - so Linda's chair does not roll backward!

Sent from my iPhone

>
> 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
 
Ramp brackets, I'll bet.
Jim Hupy

> Hey Bob D.:
> Why do you "have" to run w/ rear 2" higher? Just curious!
> Mike/The Corvair a holic
> And don't tell me - so Linda's chair does not roll backward!
>
> Sent from my iPhone
>

> >
> > 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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Jim H.:
You are probably rite - I should have thought of that!
Mike/The Corvair a holic

Sent from my iPhone

>
> Ramp brackets, I'll bet.
> Jim Hupy
>

>>
>> Hey Bob D.:
>> Why do you "have" to run w/ rear 2" higher? Just curious!
>> Mike/The Corvair a holic
>> And don't tell me - so Linda's chair does not roll backward!
>>
>> Sent from my iPhone
>>

>>>
>>> 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
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
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
 
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