| [GMCnet] Rear suspension air pressure [message #211497] |
Tue, 18 June 2013 10:59  |
RicksGMC
Messages: 145
Registered: May 2012
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Hi all,
I need a little information assistance to get my coach home. After over 9 months in the repair shop it looks like my GMC is almost ready to come home. However the rear bags are deflated and according to the shop after 20-30 min of the air pump running the bags are not filling so I obviously have a leak. I have the fittings to temporarily install in the bags to manually fill them.
The question is: what air pressure should I typically fill the bags to for safe driving? It has original OEM bags installed.
Worst case scenario is the bags themselves are shot and if so is there any chance of finding some used original bags just to allow the shop to test drive it and for me to bring it home?
My goal is to install the Sully bag or Quad bag setup later this summer once its home so I don't want to spend loads of time or money while its sitting in the repair shop.
Thanks
Rick
Rick&Tammy Drummond
Prior Lake MN
'74 (re)Painted Desert
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Rick
Rick&Tammy Drummond
Prior Lake MN
'74 (re)Painted Desert
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| Re: [GMCnet] Rear suspension air pressure [message #211498 is a reply to message #211497] |
Tue, 18 June 2013 11:07  |
powerjon
Messages: 2446
Registered: January 2004
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Start with about 80 psi, that should get you home without problems. If it appears a little go to 85 psi but no more.
JR Wright
78 Buskirk Stretch
Michigan
On Jun 18, 2013, at 11:59 AM, Rick Drummond <randts.gmc@gmail.com> wrote:
> Hi all,
> I need a little information assistance to get my coach home. After over 9 months in the repair shop it looks like my GMC is almost ready to come home. However the rear bags are deflated and according to the shop after 20-30 min of the air pump running the bags are not filling so I obviously have a leak. I have the fittings to temporarily install in the bags to manually fill them.
> The question is: what air pressure should I typically fill the bags to for safe driving? It has original OEM bags installed.
> Worst case scenario is the bags themselves are shot and if so is there any chance of finding some used original bags just to allow the shop to test drive it and for me to bring it home?
> My goal is to install the Sully bag or Quad bag setup later this summer once its home so I don't want to spend loads of time or money while its sitting in the repair shop.
> Thanks
>
> Rick
>
> Rick&Tammy Drummond
> Prior Lake MN
> '74 (re)Painted Desert
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Rear suspension air pressure [message #211501 is a reply to message #211497] |
Tue, 18 June 2013 11:34 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Install air bag isolator kit ( applied gmc $75) with shrader valve , inflate with valve in off ( perpendicular to fitting) and spray bag with soapy water solution to see if bag is leaking or maybe a fitting. This way you rule out all the plumbing. If bag not leaking, inflate until travel height is reached and boogie home.
Todd Sullivan
Sully
77 royale
Seattle
On Jun 18, 2013, at 8:59 AM, Rick Drummond <randts.gmc@gmail.com> wrote:
> Hi all,
> I need a little information assistance to get my coach home. After over 9 months in the repair shop it looks like my GMC is almost ready to come home. However the rear bags are deflated and according to the shop after 20-30 min of the air pump running the bags are not filling so I obviously have a leak. I have the fittings to temporarily install in the bags to manually fill them.
> The question is: what air pressure should I typically fill the bags to for safe driving? It has original OEM bags installed.
> Worst case scenario is the bags themselves are shot and if so is there any chance of finding some used original bags just to allow the shop to test drive it and for me to bring it home?
> My goal is to install the Sully bag or Quad bag setup later this summer once its home so I don't want to spend loads of time or money while its sitting in the repair shop.
> Thanks
>
> Rick
>
> Rick&Tammy Drummond
> Prior Lake MN
> '74 (re)Painted Desert
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: [GMCnet] Rear suspension air pressure [message #211507 is a reply to message #211497] |
Tue, 18 June 2013 12:05 |
GMC Cruse
Messages: 606
Registered: June 2009
Location: SE Michigan
Karma: 3
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| RicksGMC wrote on Tue, 18 June 2013 11:59 |
Hi all,
I need a little information assistance to get my coach home. After over 9 months in the repair shop it looks like my GMC is almost ready to come home. However the rear bags are deflated and according to the shop after 20-30 min of the air pump running the bags are not filling so I obviously have a leak. I have the fittings to temporarily install in the bags to manually fill them.
The question is: what air pressure should I typically fill the bags to for safe driving? It has original OEM bags installed.
Worst case scenario is the bags themselves are shot and if so is there any chance of finding some used original bags just to allow the shop to test drive it and for me to bring it home?
My goal is to install the Sully bag or Quad bag setup later this summer once its home so I don't want to spend loads of time or money while its sitting in the repair shop.
Thanks
Rick
Rick&Tammy Drummond
Prior Lake MN
'74 (re)Painted Desert
|
You normally don't go by pressure but go by measuring ride height of 11-11/16" using the measuring slot. Here is a thread about it.
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=170997&rid=0&srch=ride+height+measure#msg_170997
Mike K.
'75 PB
Southeast Michigan
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| Re: [GMCnet] Rear suspension air pressure [message #211514 is a reply to message #211511] |
Tue, 18 June 2013 12:58 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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I don't think anyone can state the air pressure for the original (or any other) air bag.
Once you have the Schrader fill and shut-off systems installed, inflate until the centers
of the lube points on the rear bogies are at 12.25 inches off the ground and you'll be
good to travel. Fine tuning can be done when all the other stuff gets sorted out.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
______________
*[ ]~~~[][ ][|\
*--OO--[]---O-*
> Date: Tue, 18 Jun 2013 10:35:28 -0700
> From: mr.erfisher@gmail.com
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Rear suspension air pressure
>
> here is some info on how to look for the problems
> http://www.gmcws.org/Tech/dsimmons/air_suspension/air-suspension-system.html
>
> gene
>
>
>
> On Tue, Jun 18, 2013 at 8:59 AM, Rick Drummond <randts.gmc@gmail.com> wrote:
>
> > Hi all,
> > I need a little information assistance to get my coach home. After over 9
> > months in the repair shop it looks like my GMC is almost ready to come
> > home. However the rear bags are deflated and according to the shop after
> > 20-30 min of the air pump running the bags are not filling so I obviously
> > have a leak. I have the fittings to temporarily install in the bags to
> > manually fill them.
> > The question is: what air pressure should I typically fill the bags to for
> > safe driving? It has original OEM bags installed.
> > Worst case scenario is the bags themselves are shot and if so is there any
> > chance of finding some used original bags just to allow the shop to test
> > drive it and for me to bring it home?
> > My goal is to install the Sully bag or Quad bag setup later this summer
> > once its home so I don't want to spend loads of time or money while its
> > sitting in the repair shop.
> > Thanks
> >
> > Rick
> >
> > Rick&Tammy Drummond
> > Prior Lake MN
> > '74 (re)Painted Desert
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
>
>
>
> --
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
> http://gmcmotorhome.info/
> Alternator Protection Cable
> http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Rear suspension air pressure [message #211558 is a reply to message #211548] |
Tue, 18 June 2013 17:35 |
sgltrac
Messages: 2797
Registered: April 2011
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Yes if the line leavin the bag is open.
Todd Sullivan
Sully
77 royale
Seattle
On Jun 18, 2013, at 2:45 PM, Larry Davick <ljdavick@comcast.net> wrote:
> When opening the valves can the bag deflate?
>
> Larry Davick
>
> On Jun 18, 2013, at 1:29 PM, Roger Black <r1black@comcast.net> wrote:
>
>> Do you have cut off valves installed? If yes, be sure they are open
>> to fill the bags. May sound simple but for some of US, someone has to
>> mention the obvious. <G>
>>
>> Roger Black
>> 77 Birchaven
>> Burns, Tn
>>
>>
>>
>>
>> _______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: [GMCnet] Rear suspension air pressure [message #211585 is a reply to message #211497] |
Tue, 18 June 2013 22:00 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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74 so do they have the rotary valves set right. Is the compressor putting out? If it was, after a 20 min run it may be shot . Shouldn't run more than a few mins from full down to proper ride height. Odd that both bags would he bad. Can they set one side to hold and one to raise see if it goes up then reverse sides?
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Rear suspension air pressure [message #211586 is a reply to message #211585] |
Tue, 18 June 2013 22:22 |
Mike Teets
Messages: 299
Registered: January 2004
Location: Dublin, OH
Karma: 0
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I had a problem where the pump would fill the bags about 3/4 pressure and
then just run and run. I thought it was the pump and tried another. Turns
out it was a brass elbow on the bottom of the small tank. At about 60 lbs,
a crack would open up on the bottom of the fitting allowing air to escape.
You couldn't hear it over the pump sound. I just happened to reach into
the cabinet and felt the air coming from the fitting. I suspect there was
moisture in the tank that settled into the fitting then froze over the
winter.
Mike
On Tue, Jun 18, 2013 at 11:00 PM, John R. Lebetski <gransport@aol.com>wrote:
>
>
> 74 so do they have the rotary valves set right. Is the compressor putting
> out? If it was, after a 20 min run it may be shot . Shouldn't run more than
> a few mins from full down to proper ride height. Odd that both bags would
> he bad. Can they set one side to hold and one to raise see if it goes up
> then reverse sides?
> --
> John Lebetski
> Chicago, IL
> 77 Eleganza II
> Source America First
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Mike, GMCing since 2002
77 Palm Beach, 260, 403
Dublin, OH
http://teamteets.com/gmc/
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| Re: [GMCnet] Rear suspension air pressure [message #211589 is a reply to message #211585] |
Tue, 18 June 2013 23:50 |
RicksGMC
Messages: 145
Registered: May 2012
Karma: 0
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Senior Member |
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Yes, mine has the rotary valves. The passenger bag is more deflated, the drivers side appears to have some pressure in it. They are still finishing up the engine so I can't do to much troubleshooting right now. Hoping I can get it home and look at it on my time instead of in the repair $hop on their time$$$$. 😧
Maybe I'll get lucky and they only put the left side in 'travel' and put the right side in 'lower'!?!?
Rick
Rick&Tammy Drummond
Prior Lake MN
'74 (re)Painted Desert
On Jun 18, 2013, at 10:00 PM, John R. Lebetski <gransport@aol.com> wrote:
>
>
> 74 so do they have the rotary valves set right. Is the compressor putting out? If it was, after a 20 min run it may be shot . Shouldn't run more than a few mins from full down to proper ride height. Odd that both bags would he bad. Can they set one side to hold and one to raise see if it goes up then reverse sides?
> --
> John Lebetski
> Chicago, IL
> 77 Eleganza II
> Source America First
> _______________________________________________
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> Unsubscribe or Change List Options:
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Rick
Rick&Tammy Drummond
Prior Lake MN
'74 (re)Painted Desert
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| Re: [GMCnet] Rear suspension air pressure [message #211590 is a reply to message #211589] |
Wed, 19 June 2013 00:42 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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It's 12:26 am, it's been a long day and I am about to go to bed and don't feel like doing the leg work for you. Look up how to set the ride height in the Maintenance Manual. It will provide a measurement from the ground to the middle of a slot in the frame at the rear of the coach.. Go to the Photo Site and under Mueller R you will find photos of what the slots look like and where they are.
Take the measurement provided in the MM and deduct 3 inches from it and make a block of wood (2 x 4) that long. Locate the slot in the rear of the frame on the passenger side (near the LPG tank) and have a shop guy lay down on the floor with the block of wood while you put air in the bag on the passenger side. Put air into the bag until he can just slip the block under the frame under the slot. Once that's done move over to the driver side and repeat the process. When both sides are at the correct ride height as measured with the block take a tape measure and measure from the center of the wheel well down to the ground on both sides and write that down.
Use that measurement to set the ride height until you can fix the leaks. Personally I like the Power Level as it is the simplest system that GMC used. It doesn’t control the ride height as well as the EL 1 and EL 2 but it's a damn site easier to maintain and trouble shoot.
If replace all the plastic fittings with good quality brass fittings and the OEM dash valves with a set of JR Slaten's valves you'll have a simple reliable system.
Regards,
Rob M.
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Rick Drummond
Sent: Tuesday, June 18, 2013 11:50 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Rear suspension air pressure
Yes, mine has the rotary valves. The passenger bag is more deflated, the drivers side appears to have some pressure in it. They are still finishing up the engine so I can't do to much troubleshooting right now. Hoping I can get it home and look at it on my time instead of in the repair $hop on their time$$$$. 😧
Maybe I'll get lucky and they only put the left side in 'travel' and put the right side in 'lower'!?!?
Rick
Rick&Tammy Drummond
Prior Lake MN
'74 (re)Painted Desert
On Jun 18, 2013, at 10:00 PM, John R. Lebetski <gransport@aol.com> wrote:
>
>
> 74 so do they have the rotary valves set right. Is the compressor putting out? If it was, after a 20 min run it may be shot . Shouldn't run more than a few mins from full down to proper ride height. Odd that both bags would he bad. Can they set one side to hold and one to raise see if it goes up then reverse sides?
> --
> John Lebetski
> Chicago, IL
> 77 Eleganza II
> Source America First
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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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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