Home » Public Forums » GMCnet » Required air pressure for quad bag rear suspension
Required air pressure for quad bag rear suspension [message #328867] |
Tue, 06 February 2018 09:10 |
gibsongo
Messages: 116 Registered: October 2012 Location: Montreal West, Quebec, Ca...
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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
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Re: Required air pressure for quad bag rear suspension [message #328868 is a reply to message #328867] |
Tue, 06 February 2018 09:27 |
Bullitthead
Messages: 1411 Registered: November 2013
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System pressure in my GMC is 130 psi. Everything 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.
[Updated on: Tue, 06 February 2018 09:28] Report message to a moderator
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Re: [GMCnet] Required air pressure for quad bag rear suspension [message #328870 is a reply to message #328867] |
Tue, 06 February 2018 09:45 |
jimk
Messages: 6734 Registered: July 2006 Location: Belmont, CA
Karma: 9
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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@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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Re: Required air pressure for quad bag rear suspension [message #328871 is a reply to message #328867] |
Tue, 06 February 2018 09:58 |
Larry
Messages: 2875 Registered: January 2004 Location: Menomonie, WI
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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. When lifting the front lots of weight is transferred to the rear so 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.
[Updated on: Tue, 06 February 2018 10:01] Report message to a moderator
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Re: Required air pressure for quad bag rear suspension [message #328873 is a reply to message #328867] |
Tue, 06 February 2018 10:01 |
gibsongo
Messages: 116 Registered: October 2012 Location: Montreal West, Quebec, Ca...
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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
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Re: Required air pressure for quad bag rear suspension [message #328874 is a reply to message #328867] |
Tue, 06 February 2018 10:09 |
gibsongo
Messages: 116 Registered: October 2012 Location: Montreal West, Quebec, Ca...
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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 $$ cheaper. Hopefully the saving grace is that the tow will all be on smooth 3-lane highway.
Gordon
Gordon Gibson
1976 23" Norris Upfit
Montreal West, Quebec, Canada
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Re: [GMCnet] Required air pressure for quad bag rear suspension [message #328875 is a reply to message #328874] |
Tue, 06 February 2018 10:23 |
James Hupy
Messages: 6806 Registered: May 2010
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Raise the rear to maximum suspension travel, and turn the supply air valve
off. Have the tow driver only raise the front wheels enough to give
clearance for road crowns, etc. The one time I was towed was from SeaTac to
Tacoma southbound on interstate 5 at 70 mph. No problems at all. My Royale
has stock EL II rear suspension. Your quad bag setup should not be any
problem towed this way. Unless, you have stuff hanging under the rear of
the coach that the factory didn't put there.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Feb 6, 2018 8:10 AM, "Gordon Gibson" wrote:
> Larry
> I definitely hear you and would much prefer this approach, but the rate
> quoted for a Landoll is about twice that for "the hook". Even if I eend up
> having to replace 4 KYBs the hook is hundreds of $$ 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
>
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Re: [GMCnet] Required air pressure for quad bag rear suspension [message #328883 is a reply to message #328867] |
Tue, 06 February 2018 15:42 |
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USAussie
Messages: 15912 Registered: July 2007 Location: Sydney, Australia
Karma: 6
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Gordon,
Here's an article I wrote on towing a GMC:
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@list.gmcnet.org] On Behalf Of Gordon Gibson
Sent: Wednesday, February 7, 2018 2:11 AM
To: gmclist@list.gmcnet.org
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.
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http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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Re: [GMCnet] Required air pressure for quad bag rear suspension [message #328884 is a reply to message #328883] |
Tue, 06 February 2018 15:52 |
James Hupy
Messages: 6806 Registered: May 2010
Karma: -62
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"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
On Feb 6, 2018 1:43 PM, "Rob Mueller" wrote:
> Gordon,
>
> Here's an article I wrote on towing a GMC:
>
> 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@list.gmcnet.org] On Behalf Of
> Gordon Gibson
> Sent: Wednesday, February 7, 2018 2:11 AM
> To: gmclist@list.gmcnet.org
> 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
>
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Re: [GMCnet] Required air pressure for quad bag rear suspension [message #328885 is a reply to message #328884] |
Tue, 06 February 2018 16:09 |
Carl S.
Messages: 4186 Registered: January 2009 Location: Tucson, AZ.
Karma: 13
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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
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Re: [GMCnet] Required air pressure for quad bag rear suspension [message #328888 is a reply to message #328884] |
Tue, 06 February 2018 16:49 |
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USAussie
Messages: 15912 Registered: July 2007 Location: Sydney, Australia
Karma: 6
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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@list.gmcnet.org] On Behalf Of James Hupy
Sent: Wednesday, February 7, 2018 8:52 AM
To: gmclist@list.gmcnet.org
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
On Feb 6, 2018 1:43 PM, "Rob Mueller" wrote:
> Gordon,
>
> Here's an article I wrote on towing a GMC:
>
> 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@list.gmcnet.org] On Behalf Of
> Gordon Gibson
> Sent: Wednesday, February 7, 2018 2:11 AM
> To: gmclist@list.gmcnet.org
> 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
>
_______________________________________________
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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Re: Required air pressure for quad bag rear suspension [message #328906 is a reply to message #328867] |
Tue, 06 February 2018 22:52 |
gibsongo
Messages: 116 Registered: October 2012 Location: Montreal West, Quebec, Ca...
Karma: 0
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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
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Re: Required air pressure for quad bag rear suspension [message #328916 is a reply to message #328910] |
Wed, 07 February 2018 08:10 |
Larry
Messages: 2875 Registered: January 2004 Location: Menomonie, WI
Karma: 10
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RF_Burns wrote on Wed, 07 February 2018 05:58Finding 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 least 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 coach and the truck. Choose carefully.
Larry
78 Royale w/500 Caddy
Menomonie, WI.
[Updated on: Wed, 07 February 2018 08:11] Report message to a moderator
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Re: Required air pressure for quad bag rear suspension [message #328917 is a reply to message #328867] |
Wed, 07 February 2018 08:31 |
77Royale
Messages: 461 Registered: June 2014 Location: Mid Michigan
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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
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Re: Required air pressure for quad bag rear suspension [message #328918 is a reply to message #328867] |
Wed, 07 February 2018 08:48 |
TR 1
Messages: 348 Registered: August 2015 Location: DFW
Karma: -7
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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
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