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Rear bag inflation/height cut off valves [message #368040]

Wed, 15 December 2021 17:50

boybach

Messages: 566
Registered: December 2020
Location: Vancouver Island

Karma: 4

Senior Member

Hi - Early last summer, while dicking around replacing a leaking air line connection on my passenger side, I'd loosened and moved the height valve to get the stalled inflation going again. Whether I should or shouldn't have done that, well, IDK. Keep in mind I was still pretty green in things GMC at the time.

After I buttoned it all up again I started wondering how the coach knew when to quit inflating/deflating when the level controls were set to travel. Still not clear on that BTW, but sure it has to do with the position of the valve/arm, just not squared away on how to set it up.

ATM, I have shut-off valves on the bags (OEM bags) and set the rear travel height manually using a measuring stick at the bogeys, then lock the setting by closing the shut off.

It works and the coach drives fine, but I'd prefer to have it adjust automatically.

The compressor is the OEM one but it works well. I have no air leaks either.

Any tips or explanations on getting this set up properly?

thanks guys

Larry

Larry - Victoria BC - 1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat exchange hoses

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Re: Rear bag inflation/height cut off valves [message #368044 is a reply to message #368040]

Wed, 15 December 2021 19:17

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

boybach wrote on Wed, 15 December 2021 18:50

Hi - Early last summer, while dicking around replacing a leaking air line connection on my passenger side, I'd loosened and moved the height valve to get the stalled inflation going again. Whether I should or shouldn't have done that, well, IDK. Keep in mind I was still pretty green in things GMC at the time.

After I buttoned it all up again I started wondering how the coach knew when to quit inflating/deflating when the level controls were set to travel. Still not clear on that BTW, but sure it has to do with the position of the valve/arm, just not squared away on how to set it up.

ATM, I have shut-off valves on the bags (OEM bags) and set the rear travel height manually using a measuring stick at the bogeys, then lock the setting by closing the shut off.

It works and the coach drives fine, but I'd prefer to have it adjust automatically.

The compressor is the OEM one but it works well. I have no air leaks either.

Any tips or explanations on getting this set up properly?

thanks guys

Larry

Larry,

The measure at the bogey is as good as any. If you want to know if the system is working, get the fuel and potable tanks empty and measure the ride height. Now fill the fuel and potable tanks and see if it the height is still where is should be. If it is, everything is good.

I don't know if newer 26s were worse or better, but my 73-23 can gain/loose an inch and an half.

Matt

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

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Re: Rear bag inflation/height cut off valves [message #368048 is a reply to message #368040]

Thu, 16 December 2021 00:51

JohnS

Messages: 126
Registered: December 2014
Location: Vacaville, CA

Karma: -2

Senior Member

RTFM. Section 4A of the 1977 & 1978 Maintenance Manual Supplement has extensive info on the operation and adjustment of the ElectroLevel system. The fact that you have no leaks puts you ahead of the game. The adjustment procedure is not difficult, but is tedious due to the delay time built into the height control valves. Also, if one of the height control valves has a large dead band, it may need replacement.

It is nice to have the system working correctly, as it will trim the coach up as the load changes.

JohnS

John Shutzbaugh, Vacaville, CA, ncserv@aol.com; 78 Buskirk stretch, "What were we thinking?"

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Re: Rear bag inflation/height cut off valves [message #368050 is a reply to message #368048]

Thu, 16 December 2021 01:19

boybach

Messages: 566
Registered: December 2020
Location: Vancouver Island

Karma: 4

Senior Member

JohnS wrote on Wed, 15 December 2021 22:51

RTFM. Section 4A of the 1977 & 1978 Maintenance Manual Supplement has extensive info on the operation and adjustment of the ElectroLevel system. The fact that you have no leaks puts you ahead of the game. The adjustment procedure is not difficult, but is tedious due to the delay time built into the height control valves. Also, if one of the height control valves has a large dead band, it may need replacement.

It is nice to have the system working correctly, as it will trim the coach up as the load changes.

JohnS

Yup, that's what I would like - to have it adjust itself based on load changes. At the moment I do the height setting at the start of each trip, but as I said, manually with my gauge under the bogeys.

I have a borrowed maintenance manual but no copy of the 77-78 supplement. Guess I need to get that, eh?

Larry

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Re: Rear bag inflation/height cut off valves [message #368054 is a reply to message #368050]

Thu, 16 December 2021 07:29

lqqkatjon

Messages: 2324
Registered: October 2010
Location: St. Cloud, MN

Karma: 5

Senior Member

On your el1. It basically routes air through that “height” valve in wheel well when in “travel”.

That valve then vents air out of bag or into bag to adjust height. (Wants to keep itself centered). The oem valves should have a time delay before it valves.

The easiest way to adjust ride height with those valves is to install an adjustable link to the bogie arm. Most venders have those. (There are two different lengths i believe).

Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/

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Re: Rear bag inflation/height cut off valves [message #368057 is a reply to message #368054]

Thu, 16 December 2021 11:29

boybach

Messages: 566
Registered: December 2020
Location: Vancouver Island

Karma: 4

Senior Member

lqqkatjon wrote on Thu, 16 December 2021 05:29

On your el1. It basically routes air through that “height” valve in wheel well when in “travel”.

That valve then vents air out of bag or into bag to adjust height. (Wants to keep itself centered). The oem valves should have a time delay before it valves.

The easiest way to adjust ride height with those valves is to install an adjustable link to the bogie arm. Most venders have those. (There are two different lengths i believe).

Thanks! makes sense. I also just received an emailed .pdf of the 77-78 supplement from a fellow member... Thanks all!

Larry

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[GMCnet] Re: Rear bag inflation/height cut off valves [message #368060 is a reply to message #368057]

Thu, 16 December 2021 12:40

Keith V

Messages: 2337
Registered: March 2008
Location: Mounds View,MN

Karma: 0

Senior Member

It's easy to set the ride height without the side effects of the height valve time delay and deadband.
It does work best with adjustable links...

All you have to do is:

1. remove the link from the bogie to the height valve. ( the sensor will now be in the middle its deadband )
2. adjust the coach height in manual mode to the middle of the height range.
3. adjust the link so you can reconnect the link without changing the position of the height valve
4. Done

This will eliminate any need to bounce the suspension or wait for the valve to adjust the height.
this is what I did before I got rid of the stock system

Keith Vasilakes
Mounds View MN
76 exRoyale
MicroLevel

________________________________
From: twlldeen@gmail.com
Sent: Thursday, December 16, 2021 11:30 AM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Rear bag inflation/height cut off valves

lqqkatjon wrote on Thu, 16 December 2021 05:29
> On your el1. It basically routes air through that “height” valve in wheel well when in “travel”.
>
> That valve then vents air out of bag or into bag to adjust height. (Wants to keep itself centered). The oem valves should have a time delay
> before it valves.
>
> The easiest way to adjust ride height with those valves is to install an adjustable link to the bogie arm. Most venders have those. (There are
> two different lengths i believe).

Thanks! makes sense. I also just received an emailed .pdf of the 77-78 supplement from a fellow member... Thanks all!

Larry

--
Larry - Victoria BC -

1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS
exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat exchange hoses
_______________________________________________
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com

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[GMCnet] Re: Rear bag inflation/height cut off valves [message #368061 is a reply to message #368057]

Thu, 16 December 2021 12:38

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

The links are all the same, so we supply the adjustable links.
Saves lot of time.
Also if one has the 78 system, it is different than 73-77.
There was a cut off some where 77-78

On Thu, Dec 16, 2021 at 9:30 AM wrote:

> lqqkatjon wrote on Thu, 16 December 2021 05:29
>> On your el1. It basically routes air through that “height” valve in
> wheel well when in “travel”.
>>
>> That valve then vents air out of bag or into bag to adjust height.
> (Wants to keep itself centered). The oem valves should have a time delay
>> before it valves.
>>
>> The easiest way to adjust ride height with those valves is to install an
> adjustable link to the bogie arm. Most venders have those. (There are
>> two different lengths i believe).
>
> Thanks! makes sense. I also just received an emailed .pdf of the 77-78
> supplement from a fellow member... Thanks all!
>
> Larry
>
> --
> Larry - Victoria BC -
>
> 1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working
> but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS
> exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat
> exchange hoses
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.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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[GMCnet] Re: Rear bag inflation/height cut off valves [message #368062 is a reply to message #368060]

Thu, 16 December 2021 14:32

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

I have a bunch of experience with all 4 types.
Type 1. No controls. Entirely up to the compressor and ride height
controls. All pneumatic.
Type 2. Same as Type 1, except for the knobs in the dash. Same compressor
and air tank, and a whole bunch of air lines front to rear. No electronics.
Type 3. Compressor and air hoses about the same on early models, then
compressor moved to the rear of the coach, a bunch of solenoid controlled
air valves added, along with rocker switches by the driver's left elbow.
Same ride height mechanism.
Type 4. EL-2. Everything is different, except for the rocker switches. Ride
height now controlled by electronic ride height controls. Two compressors,
lots of solenoids and valves all located in the rear of the coach. Only two
air lines. Left and right. Blue and grey. Ride height links hook up to
electronic controllers. State of the art circuit boards for the late 70's.
Uses shutter wheels and light emitting diodes and transistor sensors. All
sealed in epoxy. No user service possible.
Jim Hupy
Salem, Oregon

On Thu, Dec 16, 2021, 10:40 AM Keith V wrote:

> It's easy to set the ride height without the side effects of the height
> valve time delay and deadband.
> It does work best with adjustable links...
>
> All you have to do is:
>
> 1. remove the link from the bogie to the height valve. ( the sensor
> will now be in the middle its deadband )
> 2. adjust the coach height in manual mode to the middle of the height
> range.
> 3. adjust the link so you can reconnect the link without changing the
> position of the height valve
> 4. Done
>
> This will eliminate any need to bounce the suspension or wait for the
> valve to adjust the height.
> this is what I did before I got rid of the stock system
>
> Keith Vasilakes
> Mounds View MN
> 76 exRoyale
> MicroLevel http://www.gmcmotorhomemarketplace.com/vasilakes/microlevel_intro.pdf>
>
>
> ________________________________
> From: twlldeen@gmail.com
> Sent: Thursday, December 16, 2021 11:30 AM
> To: gmclist@list.gmcnet.org
> Subject: [GMCnet] Re: Rear bag inflation/height cut off valves
>
> lqqkatjon wrote on Thu, 16 December 2021 05:29
>> On your el1. It basically routes air through that “height” valve in
> wheel well when in “travel”.
>>
>> That valve then vents air out of bag or into bag to adjust height.
> (Wants to keep itself centered). The oem valves should have a time delay
>> before it valves.
>>
>> The easiest way to adjust ride height with those valves is to install an
> adjustable link to the bogie arm. Most venders have those. (There are
>> two different lengths i believe).
>
> Thanks! makes sense. I also just received an emailed .pdf of the 77-78
> supplement from a fellow member... Thanks all!
>
> Larry
>
> --
> Larry - Victoria BC -
>
> 1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working
> but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS
> exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat
> exchange hoses
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
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Unsubscribe or Change List Options:

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Re: Rear bag inflation/height cut off valves [message #368064 is a reply to message #368040]

Thu, 16 December 2021 16:32

boybach

Messages: 566
Registered: December 2020
Location: Vancouver Island

Karma: 4

Senior Member

I have type 3 - rocker switches at my elbow.

Larry

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Re: [GMCnet] Re: Rear bag inflation/height cut off valves [message #368068 is a reply to message #368061]

Thu, 16 December 2021 17:51

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

jimk wrote on Thu, 16 December 2021 13:38

The links are all the same, so we supply the adjustable links.
Saves lot of time.
Also if one has the 78 system, it is different than 73-77.
There was a cut off some where 77-78
--
Jim Kanomata ASE

For those that care, I have a friend's donor coach next to my barn. Its VIN says it is a 78, but it had EL1.

Matt

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Re: [GMCnet] Re: Rear bag inflation/height cut off valves [message #368070 is a reply to message #368060]

Thu, 16 December 2021 19:01

Ken Burton

Messages: 10030
Registered: January 2004
Location: Hebron, Indiana

Karma: 10

Senior Member

DUH!!!! Why didn't I think of the procedure before.

Ken B.

Keith V wrote on Thu, 16 December 2021 12:40

It's easy to set the ride height without the side effects of the height valve time delay and deadband.
It does work best with adjustable links...

All you have to do is:

1. remove the link from the bogie to the height valve. ( the sensor will now be in the middle its deadband )
2. adjust the coach height in manual mode to the middle of the height range.
3. adjust the link so you can reconnect the link without changing the position of the height valve
4. Done

This will eliminate any need to bounce the suspension or wait for the valve to adjust the height.
this is what I did before I got rid of the stock system

Keith Vasilakes
Mounds View MN
76 exRoyale
MicroLevel

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Re: Rear bag inflation/height cut off valves [message #368071 is a reply to message #368040]

Thu, 16 December 2021 19:39

Tom Katzenberger

Messages: 399
Registered: June 2019
Location: Kingsville, MD

Karma: 4

Senior Member

And now System #5 - Keith V's "Microlevel"

Which I am loving
Tom K.

Tom & Oki Katzenberger, Kingsville, Maryland, 1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition

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Re: [GMCnet] Re: Rear bag inflation/height cut off valves [message #368092 is a reply to message #368070]

Fri, 17 December 2021 19:54

JohnS

Messages: 126
Registered: December 2014
Location: Vacaville, CA

Karma: -2

Senior Member

Ditto on the DUH!!! Always nice to learn something new.

JohnS

John Shutzbaugh, Vacaville, CA, ncserv@aol.com; 78 Buskirk stretch, "What were we thinking?"

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