| Air Tank Size and other air suspension questions [message #72817] |
Thu, 04 February 2010 16:14  |
Mike O'Connell
Messages: 53
Registered: November 2008
Location: Deerfield MA
Karma: 0
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I'm refurbishing my air suspension, gutted by a PO, and I'm trying to determine the proper size for the air tank.I have a Viair 480C, which I assume to be more powerful than the original unit. I'm thinking 3 gallons may be the right size. I'd like to have enough air to change the pressure in the bags from low to high without having the compressor do all the work while it's being changed.
The PO took out the Height Control Valves and installed a "Air Lift" compressor (kinda small) routed directly to a set of solenoid valves with gauges in the dash and on to the air bags. As it presently sits I have only "raise" and "lower" functionality to each of the bags. Will I need/miss the auto leveling function?
If I can set the height by air pressure readings (and experience), I'd do without the expense of restoring the old system. Also is there an electronic replacement for the Height Control Valve so I could wire them up to air valves by the tank and don't need to run air hose everywhere.
Mike O'Connell
Deerfield, MA
'75 Eleganza
[Updated on: Thu, 04 February 2010 17:07] Report message to a moderator |
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| Re: [GMCnet] Air Tank Size and other air suspension questions [message #72828 is a reply to message #72826] |
Thu, 04 February 2010 17:15  |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
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Senior Member |
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Jim makes OEM replacement tanks. I have one for my 23. About a gallon I
think. Very nicely done. I'm not sure if the Coop or Applied sell these as
well
Jim DeMaere - Tanks, Stainless Steel replacement air and hot water.
403-329-3091 Lethrbridge, Alberta
Thanks
Gary and Joanne Worobec
1973 GMC Glacier
Anza, CA
----- Original Message -----
From: "Steven Ferguson" <botiemad11@gmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Thursday, February 04, 2010 3:09 PM
Subject: Re: [GMCnet] Air Tank Size and other air suspension questions
>I think it's one gallon.
>
> On Thu, Feb 4, 2010 at 3:54 PM, Mike O'Connell <moconnell2000@yahoo.com>
> wrote:
>>
>>
>> Does anyone know what the OEM air tank size is?
>> --
>> Mike O'Connell
>> Deerfield, MA
>> '75 Eleganza
>> _______________________________________________
>> GMCnet mailing list
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>
>
>
> --
> Steve Ferguson
> '76 EII
> Sierra Vista, AZ
> Urethane bushing source
> www.bdub.net/ferguson/
> _______________________________________________
> GMCnet mailing list
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| Re: [GMCnet] Air Tank Size and other air suspension questions [message #72834 is a reply to message #72817] |
Thu, 04 February 2010 17:57 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Mike,
To help you with your problem I have copied your questions and provided
responses below.
Query: I have a Viair 480C, which I assume to be more powerful than the
original unit.
Response: I think you are correct as this model is one of the most
"powerful" they sell. Here's a link to this compressor on their website
where I found the specs below:
http://www.viaircorp.com/OnRoad/index.html
480C Performance Data *Supply Voltage: 13.8 Volts
PSI CFM
0 1.76
10 1.66
20 1.59
30 1.52
40 1.45
50 1.41
60 1.34
70 1.27
80 1.20
90 1.16
100 1.13
110 1.06
120 1.02
130 0.95
140 0.92
150 0.85
160 0.81
170 0.74
180 0.70
190 0.63
200 0.56
480C Fill Rates
2.5 Gallon Tank Fill Rate
0 To 145 PSI 2 Min. 29 Sec.
110 To 145 PSI 57 Sec.
0 To 200 PSI 5 Min. 02 Sec.
165 To 200 PSI 1 Min. 23 Sec.
5.0 Gallon Tank Fill Rate
0 To 145 PSI 6 Min. 02 Sec.
110 To 145 PSI 1 Min. 55 Sec.
0 To 200 PSI 10 Min. 08 Sec.
165 To 200 PSI 2 Min. 20 Sec.
Query: I'm thinking 3 gallons may be the right size.
Response: I don't know but here's a link to the stainless steel tanks on Jim
K's Applied GMC website:
Large SS Tank: http://www.appliedgmc.com/prod.itml/icOid/686
Small SS Tank: http://www.appliedgmc.com/prod.itml/icOid/687
Unfortunately it does not provide the volume of the tanks.
Query: If I can set the height by air pressure readings (and experience),
I'd do without the expense of restoring the old system.
Response: It is possible to set the ride height using the pressure gages.
However, the problem is that the amount of pressure would vary with the
weight of the coach. To establish a base line you would have to load up the
GMC like it would be if you were going on a trip. Park it in a level area
and pump up the air bags to meet the ride height settings as noted in
Maintenance Manual (MM) X-7525 Page 4-34 Figure 70 - Checking Vehicle Ride
Height. When you have that done measure the distance from the ground to the
lip of the rear wheel wells in the middle between both wheels and record
that measurement. Also record the pressure readings on both the dashboard
gages. Don't be surprised if they are not the same! As long as the weight in
the GMC doesn't vary a great deal you should be OK.
If you don't want to have to go through this then you would have to replace
the OEM rear suspension ride control system which I believe in a '75
Eleganza would have been the Power Level system. See MM X-7525 SECTION 4 -
REAR SUSPENSION.
Here's a link to Rick Denny's EXCELLENT write up of the Power Level System:
http://www.gmceast.com/technical/Denney_Power_Level_System.pdf
Here's your one-stop shop for the parts you'll need.
Applied GMC Parts:
Ride Height Valves:
http://www.appliedgmc.com/prod.itml/icOid/738
Large SS Tank:
http://www.appliedgmc.com/prod.itml/icOid/686
Small SS Tank:
http://www.appliedgmc.com/prod.itml/icOid/687
Ride Height Valves:
http://www.appliedgmc.com/prod.itml/icOid/685
Nylon Tubing:
http://www.appliedgmc.com/prod.itml/icOid/894
Pressure switch with unloader valve:
http://www.appliedgmc.com/prod.itml/icOid/816
Pressure switch without unloader valve:
http://www.appliedgmc.com/prod.itml/icOid/817
Air Suspension Trap w/SS Check Valve, Air Filter, Fitting and Hose:
http://www.appliedgmc.com/prod.itml/icOid/689
Air Bag Isolator Kit:
http://www.appliedgmc.com/prod.itml/icOid/690
Jim does not list the individual fittings but I'm sure he could get them for
you.
Query: Will I need/miss the auto leveling function?
Response: The auto level system resets the ride height as the weight of the
GMC changes (fuel tanks empty). Is that really necessary you ask. In the
mornings before we set off I change the Power Level system setting in Double
Trouble from "Hold" (where it has been overnight) to "Travel." I allow the
ride height control valves to set the ride height then I close the air bag
isolation valves.
I think this should cover your questions.
I know absolutely nothing about the Electro Level I or Electro Level II
system so THIS IS IT as far as I'm concerned.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mike O'Connell
Sent: Friday, 5 February 2010 9:14 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Air Tank Size and other air suspension questions
I'm refurbishing my air suspension, gutted by a PO, and I'm trying to
determine the proper size for the air tank. I have a Viair 480C, which I
assume to be more powerful than the original unit. I'm thinking 3 gallons
may be the right size. I'd like to have enough air to change the pressure in
the bags from low to high without having the compressor do all the work
while it's being changed.
The PO took out the Height Control Valves and installed a "Air Lift"
compressor (kinda small) routed directly to a set of solenoid valves with
gauges in the dash and on to the air bags. As it presently sits I have only
"raise" and "lower" functionality to each of the bags. Will I need/miss the
auto leveling function?
If I can set the height by air pressure readings (and experience), I'd do
without the expense of restoring the old system. Also is there an electronic
replacement for the Height Control Valve so I could wire them up to air
valves by the tank and don't need to run air hose everywhere.
--
Mike O'Connell
Deerfield, MA
'75 Eleganza
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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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: Air Tank Size and other air suspension questions [message #72850 is a reply to message #72817] |
Thu, 04 February 2010 20:05 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| Mike O'Connell wrote on Thu, 04 February 2010 14:14 |
I'm refurbishing my air suspension, gutted by a PO, and I'm trying to determine the proper size for the air tank. ...
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Mike,
IMHO, Unless you use the air pump for something other than suspension (like an air horn) you really do not need a air tank. BUT You DO need something to separate out the water that WILL be in the air. One of the suppliers sold a tank replacement made out of some pipe and a drain valve. I can not find the link right now.
If my air system was ever "gutted" my thoughts on a replacement would be something "like" the Electro-Level II system in the late 1978 coaches. Very simple system. One pump for each side. If you need it to go up, run the pump. If you need it to go down, open the vent solenoid. (The vent solenoid is internal to the OEM pump.) There is also a cut off solenoid on each side, with very little air line. A pair of pumps like your current Viair 480C would, most likely, be over-kill.... but it would pump up pretty quickly!
You can get electric height sensors from many GM cars, like the Cadillac Eldorado. Once I picked up two sensors and pumps to modify my '73 (Power Level), but ended up using the sensors to repair my '78.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: Air Tank Size and other air suspension questions [message #72859 is a reply to message #72817] |
Thu, 04 February 2010 21:22 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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Senior Member |
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Leigh Harrison has those listed on his web site. I don't know that the air tank is really necessary if the compressor is working, but the drain valve certainly is necessary to get rid of the water in the lines.
George Rudawsky
Chicago, IL
75 Palm Beach
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