To Tank or Not to Tank, That is the question...

1976GMC

1976GMC

Active member
Dec 16, 2017
259
39
28
Washington State
I finally got "forced" to address the air ride system on my coach. today I went in to pump up the rear suspension, so that I can do some work around
the black tank, only to discover that the system would not build up pressure. It turns out, I got a small pinhole rusted out in the air tank. That
gave me an excuse to pull the tank and old trusty Dana compressor out. I have a brand new Viair 480C compressor sitting in the box patiently waiting
for being married to my coach. Looks like the time has come to take care of that. I've seem some posts about using these compressors with and
without air tanks on our coaches. Is there a preferred method? Benefits/drawbacks of going with and without tank. As far as a pressure cutoff switch
- what pressure rating should I be looking for? Compressor is rated for 200 PSI, but the old tank is 150 PSI. That makes me think the entire air
ride system is likely runs on much lower pressure.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
Without tank you might get nuisance starts on the compressor and possible short cycling. Also all the condensate water will go into bags, my 2
cents. Do you think GM would pay for stuff that was not needed?
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
I'm with John L on this but would go a little better with a bigger tank....say a 2 gallon if you have the space for it. Then add an air chuck that you
can hook up an air hose to for filling tires etc. Can't tell you how many times I have had to fix a bike tire or air'd up a tire on my coach that went
down while parked in a campground. Having remote air while on the road is really convenient. JWIT
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
I was thinking along the same lines - I'd like to have an ability to run tire/toy inflation if needed. I'll stay with the tank. I might re-use
existing tank if I'm able to repair it, then look for an "upgrade" for my Christmas present :)
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
I have the stock EL11 System with dual pumps and no tank. It works great so far. But I’ve noticed that most all the new aftermarket air ride systems
for hot rods and low riders are using single pumps with a air tank.. so if it was me, I would use your new pump with a bigger tank.
Scott
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas
 
The compressor that you already have, the ViAir 480 is top of the line
product. It out performs any compressor that GM ever used in our coaches.
All it really needs is a condensing/coalescing water trap and a 1 gallon
stainless steel tank with a low point drain and it will outlast your GMC,
or you for that matter. Jim Duchesne in Canada makes a tank like i
describe, and markets them through our vendors.
Jim Hupy
Salem, Oregon

On Sun, Sep 27, 2020, 8:46 AM Scott Nutter via Gmclist <

> I have the stock EL11 System with dual pumps and no tank. It works great
> so far. But I’ve noticed that most all the new aftermarket air ride systems
> for hot rods and low riders are using single pumps with a air tank.. so if
> it was me, I would use your new pump with a bigger tank.
> Scott
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final
> drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
> installed MSD Atomic EFI
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Water trap is a good idea. On all of my work equipment that uses air for various actuator control, have the water trap and even lubrication control.
Since there are no mechanical driven pieces at the end of the lines, I don't think I'll need lubrication system, just water separator. Do I need to
install the water trap between the air compressor and the tank or does it do between tank and level control?? Also, as far as the stainless steel
tank - by "our vendors" do you mean Applied GMC? What other vendors would stock that type of a tank?
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
Between the compressor and the tank. Applied is one vendor that has the
tanks.
Jim Hupy
Salem, Oregon

On Sun, Sep 27, 2020, 6:54 PM Vadim Jitkov via Gmclist <

> Water trap is a good idea. On all of my work equipment that uses air for
> various actuator control, have the water trap and even lubrication control.
> Since there are no mechanical driven pieces at the end of the lines, I
> don't think I'll need lubrication system, just water separator. Do I need
> to
> install the water trap between the air compressor and the tank or does it
> do between tank and level control?? Also, as far as the stainless steel
> tank - by "our vendors" do you mean Applied GMC? What other vendors would
> stock that type of a tank?
> --
> Vadim Jitkov
> '76 Glenbrook 26'
> Pullman, WA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Since I'm gong to be upgrading the tank, will likely run new hoses to add a quick connect coupler for external air (air-out) and shrader valve
(air-in) for manual system pressurizing. I'm considering going with the Prestolok type (pushlock) of adapters and the plastic tubing instead of old
school NPT fittings and rubber hoses. I think this will give me a better chance to route tubing nice and clean in the already busy engine
compartment. I believer this is the type of tubing that is already used on coaches for the air suspension. Does anyone know if I need to use a
polyamide tubing or some other type, since it will "live" in the hot engine compartment? What would be a proper tube diameter? At least on my coach,
the tube running from the tank to the level system is very small (1/4"?). If someone can point me out to a good information source on the web about
flow rates for the plastic tubing with such pushlock system, I'd be happy to learn more about these systems and general pneumatic. I'm not a fan of
"nobody ever when wrong by making it bigger" school of thought, so I'm trying to not oversize things unnecessarily.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
interesting discussion. I was working on a 73 coach this past weekend, and we are upgrading the air suspension system on it to the microlevel
system.

even though it seems to be an almost original stored indoors 73 seqoia with 60k miles... the PO has done messed up the OEM air system. found the OEM
tank gone, it has the original dana air compressor, that they re-mounted, put the stupid air pressure switch in an almost impossible to access
location. Then a quagmire of air fittings off that, to a home made pipe-bomb looking short air tank.

I remounted a NOS dana compressor we found, and I was planning on not using an air tank. it seems as time progresses with GMC's they slowly shrunk
then finally removed the air tanks. I might be re-thinking now as you bring up the water issue.

My 75 had an retro fitted EL1 system in it... I have a Vlair mounted where the old dana was up front, and it has the air tank up front too. I
have since switched to the microlevel, but still have the air tank, air compressor in front. I have never tried to drain water out of the tank...
I am going to look to see if it even has a drain, as I just can't picture it in my head of having one.

I have a small tank from a 77 system that i can install in the 73.

my thoughts are you will have quicker air bag inflation without a tank. Less volume to bring up to a pressure.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
> my thoughts are you will have quicker air bag inflation without a tank. Less volume to bring up to a pressure.

While this is likely to be true, I don't think the difference is going to be that dramatic. At least not as dramatic as with having a hole in the
tank :). Here is my thought process:
Stock tank is 1 gal volume.
Quadra bags combined volume = 1 gal. (I'm being extremely generous here. Most likely it is smaller volume. BTW, does anyone know the bag volume?).
Lets go from 0 PSI, fully lowered suspension to 120 PSI fully raised height.

In this situation you'll need to pump twice amount of air to fill both tank and bags with pressurized air, which we can generally assume going to take
twice as long. Without tank, air will be going straight to bags and your demand is only 1 gal of pressurized air. However, if you have a tank, air
compressor can first pressurize the tank (when you turn on ignition), and only then send the shot of air to suspension elements when the switches are
set to travel or raise positions. I think when the tank is pressurized the rate of change might be faster with the tank than without it. At the same
time, if tank retains any pressure (say at the dump site when you had to lower the back), it will not take any extra time to build up pressure in the
tank and to raise the back to travel.
In any case, I'm looking forward to trying the "no tank" setup for our short trip. Then when tank is re-installed, I can see if the air compressor
cycling is different with/without the tank and if there is noticeable difference in ride height change rates.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
Actually, the compressor doesn't fill the tank first and then the bags. It will fill them all simultaneously to the chosen ride height. The only time
it would take longer to come to full pressure with a tank vs no tank would be at initial startup and I would think it would be nominal.

> > my thoughts are you will have quicker air bag inflation without a tank. Less volume to bring up to a pressure.
>
> While this is likely to be true, I don't think the difference is going to be that dramatic. At least not as dramatic as with having a hole in the
> tank :). Here is my thought process:
> Stock tank is 1 gal volume.
> Quadra bags combined volume = 1 gal. (I'm being extremely generous here. Most likely it is smaller volume. BTW, does anyone know the bag
> volume?).
> Lets go from 0 PSI, fully lowered suspension to 120 PSI fully raised height.
>
> In this situation you'll need to pump twice amount of air to fill both tank and bags with pressurized air, which we can generally assume going to
> take twice as long. Without tank, air will be going straight to bags and your demand is only 1 gal of pressurized air. However, if you have a tank,
> air compressor can first pressurize the tank (when you turn on ignition), and only then send the shot of air to suspension elements when the
> switches are set to travel or raise positions. I think when the tank is pressurized the rate of change might be faster with the tank than without
> it. At the same time, if tank retains any pressure (say at the dump site when you had to lower the back), it will not take any extra time to build
> up pressure in the tank and to raise the back to travel.
> In any case, I'm looking forward to trying the "no tank" setup for our short trip. Then when tank is re-installed, I can see if the air
> compressor cycling is different with/without the tank and if there is noticeable difference in ride height change rates.

--
Patti & Jerry Burt Fresno, CA.
73 Gmc 26' Canyon Lands
77 Palm Beach - Parts Coach - SOLD
Members: FMCA - GMCMI - GMCWS
A truly happy person is one who can enjoy the scenery on a detour.
 
there are too many variables.

if you look at the stock bags, you are pumping to 80-100 psi. Sully bags only to 30-50psi. but.. sully looks to have more volume?

I just know it takes way more time to pump 65 psi into my coach tires then it does to pump 65 psi into a bike tire using the same compressor. if the
tank of the compressor is not huge, you are usually back to hearing a compressor run. the air bag volume has to be close more then then air tank
volume. your not getting much air out of that tank into the bags before the work jumps to the compressor to raise the pressure, especially when you
are trying to get a stock airbag from 80 psi up to 100 psi.


--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
> Actually, the compressor doesn't fill the tank first and then the bags. It will fill them all simultaneously to the chosen ride height.

Fair point, except when you are parked for camping or long time, you are likely to have height control in the "Hold" position. But I agree, the
difference will be small and not really significant.
Does anyone know the volume of the Quadra Bag setup? They appear to be close or larger diameter vs. stock. At the same time, it seems that two bags
on each side will likely have smaller total volume than the single large bag.
--
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
 
I was replying to your 1 gal. example. This discussion is simply an exercise in theory. In reality, Jon's reply is correct.
In your example of the hold position while camping, the reserve tank would prove beneficial. Should the pressure drop in the bags and there were no
leaks in the lines, the reserve pressure in the tank would adjust the pressure in the bags without the need of the compressor.
This is assuming the compressor is set to shut off above the psi needed to fill the bags. Also, with or without the tank, the lines between the comp
and bag switch act as a reserve. Very little reserve but still... we are talking hypothetical. Realistically, Jon is correct, too many variables.
I like the tank for other uses.

> > Actually, the compressor doesn't fill the tank first and then the bags. It will fill them all simultaneously to the chosen ride height.
>
> Fair point, except when you are parked for camping or long time, you are likely to have height control in the "Hold" position. But I agree, the
> difference will be small and not really significant.
> Does anyone know the volume of the Quadra Bag setup? They appear to be close or larger diameter vs. stock. At the same time, it seems that two
> bags on each side will likely have smaller total volume than the single large bag.

--
Patti & Jerry Burt Fresno, CA.
73 Gmc 26' Canyon Lands
77 Palm Beach - Parts Coach - SOLD
Members: FMCA - GMCMI - GMCWS
A truly happy person is one who can enjoy the scenery on a detour.
 
Those Air systems on the early coaches needed the large air tank, because
they all leaked air. Many owners after growing tired of chasing leaks for
years, installed shut off valves at the air bags. They always closed them
when the coaches sat at rallies and storage. The EL 2 system can be made to
be leak free. But, not the early coaches. Even with the Slaten valves in
the dash, there was just too many hoses and too many connections in those
flexible fliers. I have worked on too many of those coaches to count.
Jim Hupy
Salem, Oregon

On Tue, Sep 29, 2020, 11:24 AM Jerry Burt via Gmclist <

> I was replying to your 1 gal. example. This discussion is simply an
> exercise in theory. In reality, Jon's reply is correct.
> In your example of the hold position while camping, the reserve tank would
> prove beneficial. Should the pressure drop in the bags and there were no
> leaks in the lines, the reserve pressure in the tank would adjust the
> pressure in the bags without the need of the compressor.
> This is assuming the compressor is set to shut off above the psi needed to
> fill the bags. Also, with or without the tank, the lines between the comp
> and bag switch act as a reserve. Very little reserve but still... we are
> talking hypothetical. Realistically, Jon is correct, too many variables.
> I like the tank for other uses.
>

> > > Actually, the compressor doesn't fill the tank first and then the
> bags. It will fill them all simultaneously to the chosen ride height.
> >
> > Fair point, except when you are parked for camping or long time, you are
> likely to have height control in the "Hold" position. But I agree, the
> > difference will be small and not really significant.
> > Does anyone know the volume of the Quadra Bag setup? They appear to be
> close or larger diameter vs. stock. At the same time, it seems that two
> > bags on each side will likely have smaller total volume than the single
> large bag.
>
>
> --
> Patti & Jerry Burt Fresno, CA.
> 73 Gmc 26' Canyon Lands
> 77 Palm Beach - Parts Coach - SOLD
> Members: FMCA - GMCMI - GMCWS
> A truly happy person is one who can enjoy the scenery on a detour.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> Those Air systems on the early coaches needed the large air tank, because they all leaked air. Many owners after growing tired of chasing leaks
> for years, installed shut off valves at the air bags. They always closed them when the coaches sat at rallies and storage. The EL 2 system can be
> made to be leak free. But, not the early coaches. Even with the Slaten valves in the dash, there was just too many hoses and too many connections in
> those flexible fliers. I have worked on too many of those coaches to count.
> Jim Hupy
> Salem, Oregon

Jim, until we landed in the median at 60MPH, my system was leak free. I could leave the her sitting for weeks and when I put the key in - Nothing. I
can tell you where just about every PL1 leaks. If you have the OE valves, they have cork body gaskets. Cork is not a good air seal. But if anybody
cares, you can get some of the Loctite 567 and coat the surfaces of the cork gasket, you can make it "forever" tight and still get it apart should yo
ever need to do so.
Right now, the airsprings will hold about forever, but there is a system leak that I have to find.

If I really wanted to keep it and keep it leak free, I would buy JR's valves.

Matt
--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
 
I keep a set of J.R.'s valves on hand so I do not have to wait for a set to
ship. If I see a oem set of valves in a coach, that is where I spray bubble
soap first. Almost without fail, there will be a whole cluster of bubbles
very quickly. I always go through the drill of tightening all the air line
fittings, just before I take my razor tubing cutter out and start cutting
hoses.
I do, of course, always try to hold the costs down by fixing what I
can. Then if that is unsuccessful, I do make and market a cordless,
wireless air system that solves all the leaks at once. I suggest that as a
last resort, after we have exhausted all lower cost remedies. I have one
installed in my personal coach, wouldn't trade it for any other system that
I have encountered, yet.
Jim Hupy
Salem, Oregon

On Tue, Sep 29, 2020, 4:57 PM Matt Colie via Gmclist <

> > Those Air systems on the early coaches needed the large air tank,
> because they all leaked air. Many owners after growing tired of chasing
> leaks
> > for years, installed shut off valves at the air bags. They always closed
> them when the coaches sat at rallies and storage. The EL 2 system can be
> > made to be leak free. But, not the early coaches. Even with the Slaten
> valves in the dash, there was just too many hoses and too many connections
> in
> > those flexible fliers. I have worked on too many of those coaches to
> count.
> > Jim Hupy
> > Salem, Oregon
>
> Jim, until we landed in the median at 60MPH, my system was leak free. I
> could leave the her sitting for weeks and when I put the key in - Nothing.
> I
> can tell you where just about every PL1 leaks. If you have the OE valves,
> they have cork body gaskets. Cork is not a good air seal. But if anybody
> cares, you can get some of the Loctite 567 and coat the surfaces of the
> cork gasket, you can make it "forever" tight and still get it apart should
> yo
> ever need to do so.
> Right now, the airsprings will hold about forever, but there is a system
> leak that I have to find.
>
> If I really wanted to keep it and keep it leak free, I would buy JR's
> valves.
>
> Matt
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
The air systems on our coaches were great for their time and have functioned on the coaches till this day with minimal repairs. That with standing the market for air ride components and parts is abundant. We’ve abandoned our old out of date system with manual switches and a valve body block that takes up no space. I’ve built my fair share of vehicles with full air ride systems from simple to overly complicated. There’s no need to over complicate your repair. Your compressor should be connected to a tank to limit the constant running. Like said a water/desiccant trap should be installed in between the tank and compressor. Moisture will be the death of any air system. Reinstall your lines to your valve setup and call it a day.

Sent from my iPhone

>
> I keep a set of J.R.'s valves on hand so I do not have to wait for a set to
> ship. If I see a oem set of valves in a coach, that is where I spray bubble
> soap first. Almost without fail, there will be a whole cluster of bubbles
> very quickly. I always go through the drill of tightening all the air line
> fittings, just before I take my razor tubing cutter out and start cutting
> hoses.
> I do, of course, always try to hold the costs down by fixing what I
> can. Then if that is unsuccessful, I do make and market a cordless,
> wireless air system that solves all the leaks at once. I suggest that as a
> last resort, after we have exhausted all lower cost remedies. I have one
> installed in my personal coach, wouldn't trade it for any other system that
> I have encountered, yet.
> Jim Hupy
> Salem, Oregon
>
>
>> On Tue, Sep 29, 2020, 4:57 PM Matt Colie via Gmclist <

>>

>>> Those Air systems on the early coaches needed the large air tank,
>> because they all leaked air. Many owners after growing tired of chasing
>> leaks
>>> for years, installed shut off valves at the air bags. They always closed
>> them when the coaches sat at rallies and storage. The EL 2 system can be
>>> made to be leak free. But, not the early coaches. Even with the Slaten
>> valves in the dash, there was just too many hoses and too many connections
>> in
>>> those flexible fliers. I have worked on too many of those coaches to
>> count.
>>> Jim Hupy
>>> Salem, Oregon
>>
>> Jim, until we landed in the median at 60MPH, my system was leak free. I
>> could leave the her sitting for weeks and when I put the key in - Nothing.
>> I
>> can tell you where just about every PL1 leaks. If you have the OE valves,
>> they have cork body gaskets. Cork is not a good air seal. But if anybody
>> cares, you can get some of the Loctite 567 and coat the surfaces of the
>> cork gasket, you can make it "forever" tight and still get it apart should
>> yo
>> ever need to do so.
>> Right now, the airsprings will hold about forever, but there is a system
>> leak that I have to find.
>>
>> If I really wanted to keep it and keep it leak free, I would buy JR's
>> valves.
>>
>> Matt
>> --
>> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
>> GMCES
>> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
>> Brakes with Applied Control Arms
>> SE Michigan - Near DTW - Twixt A2 and Detroit
>>
>> _______________________________________________
>> 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
 
Matt,
Thank you for a specific suggestion on PL1. I have an October '73 coach and while it drives, rides and camps wonderfully, it has had a slight leak for
a long time. I now suspect that it is an internal rust problem at the tank and I'll be replacing that and adding a water trap. Years of soapy water
diagnostics have shown me that my fittings do not leak, even with the complication of the quad bag system. I am also going to rebuild the OEM valves
with a kit from JimK and your suggestion will be taken. Any further insights?
Doug
--
Douglas & Virginia Smith
dsmithy18 at gmail
Lincoln Nebraska
’73 “Canyonlands” since ‘95: Wanabizo"
Quadrabag/6 wheel disks/3;70 final/Paterson QuadraJet/Thorley’s/Sundry other
Alloy wheels(finally!)
 
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