Rear bag inflation/height cut off valves

[Matt Colie]

> 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

 

[john shutzbaugh]

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;
78 Buskirk stretch, "What were we thinking?"

 

[boybach]

> 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

--
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

 

[LQQKatJon]

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/

 

[boybach]

> 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

 

[jim kanomata1]

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 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
http://www.gmcrvparts.com
1-800-752-7502

 

[Keith V]

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
MicroLevelhttp://www.gmcmotorhomemarketplace.com/vasilakes/microlevel_intro.pdf

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

> 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 Hupy]

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

> 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
> Sent: Thursday, December 16, 2021 11:30 AM
> To: gmclist
> Subject: [GMCnet] Re: Rear bag inflation/height cut off valves
>

> > 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:
>

 

[boybach]

I have type 3 - rocker switches at my elbow.

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

 

[Matt Colie]

> 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
--
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

 

[Ken B]

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

Ken B.

> 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

 

[Tom Katzenberger]

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

 

[boybach]

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