Home » Public Forums » GMCnet » Quad bag height adjustment
| Quad bag height adjustment [message #370087] |
Fri, 08 July 2022 07:07  |
Green machine
Messages: 184
Registered: July 2019
Location: North Vancouver BC
Karma: 5
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Senior Member |
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Hello all,
After years of renovation/rebuilding I finally blew the dust off the old girl and took her for her maiden voyage( with me anyway) a couple weeks back. I am happy to report everything went well with the exception of some overheating issues which I am in the process of remedying.
My coach lives atop a very steep driveway, and in order to clear the rear bumper on arrival or departure I need about 100 lbs. of pressure in my bags. On my voyage I was messing with pressures and heights and found around 70 lbs. was giving me a fairly even and comfortable height.
My question is, if I set the ride height adjustment via the adjustment lever to the proper height (again, around 70 lbs) am I still able to put 100 lbs. in to deal with my driveway incline or will it just continue to bleed out any air above the 70 lb adjustment?
Thanks,
Shawn
Shawn Harris
North Vancouver,
Canada
1977 Palm Beach 403
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| Re: Quad bag height adjustment [message #370091 is a reply to message #370087] |
Fri, 08 July 2022 08:15  |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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I seem to be getting double messages posted on the web version lately, one from web forum and one through the email system. So I'll pick this one to answer on.
You have a '77 Palm beach like mine, so you should have ElectroLevel I with electric switch height controls on the left side. With the center switch on Hold position, you can use the Driver & Passenger switches to manually raise and lower the rear suspension. When you return those switches to the center position, it will hold at the current pressure and height. With the center switch in the Travel position, the rear suspension ride height (pressure) will be controlled by the Ride Height Control Valves in the wheel wells.
So you set the Ride Height Control Valves to the proper ride height for traveling down the road. I like to use Travel position for the first minute or so once I am on the road to set the height, then I switch to Hold mode. When you come to your driveway, set the center switch to HOLD then use the Raise position of the two outside switches to increase the rear pressure (height) to get in your driveway. Once you raise the rear, moving the switches back to the center position will maintain that ride height. When you leave your driveway, move the center switch to Travel and the coach will assume the proper ride height based on the rear height control valve settings.
You will find the coach runs down the road better if the rear is slightly lower than the front when set to the proper ride height. The measurements are in the Service Manual. There are several theories for this, but mine is that with the bogie pins set slightly below the center of the rear wheels, the bogies will be sitting in a more directionally stable position (think of lying in a hammock). If you increase the ride height to make the coach more "Level" front to back, then the bogie pins will be above the center of the rear wheels and the bogies become less directionally stable and the rear will start to steer a bit.
Just my farmboy mechanic way of seeing things.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| [GMCnet] Re: Quad bag height adjustment [message #370092 is a reply to message #370087] |
Fri, 08 July 2022 08:15 |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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I seem to be getting double messages posted on the web version lately, one from web forum and one through the email system. So I'll pick this one to
answer on.
You have a '77 Palm beach like mine, so you should have ElectroLevel I with electric switch height controls on the left side. With the center switch
on Hold position, you can use the Driver & Passenger switches to manually raise and lower the rear suspension. When you return those switches to the
center position, it will hold at the current pressure and height. With the center switch in the Travel position, the rear suspension ride height
(pressure) will be controlled by the Ride Height Control Valves in the wheel wells.
So you set the Ride Height Control Valves to the proper ride height for traveling down the road. I like to use Travel position for the first minute
or so once I am on the road to set the height, then I switch to Hold mode. When you come to your driveway, set the center switch to HOLD then use the
Raise position of the two outside switches to increase the rear pressure (height) to get in your driveway. Once you raise the rear, moving the
switches back to the center position will maintain that ride height. When you leave your driveway, move the center switch to Travel and the coach
will assume the proper ride height based on the rear height control valve settings.
You will find the coach runs down the road better if the rear is slightly lower than the front when set to the proper ride height. The measurements
are in the Service Manual. There are several theories for this, but mine is that with the bogie pins set slightly below the center of the rear
wheels, the bogies will be sitting in a more directionally stable position (think of lying in a hammock). If you increase the ride height to make the
coach more "Level" front to back, then the bogie pins will be above the center of the rear wheels and the bogies become less directionally stable and
the rear will start to steer a bit.
Just my farmboy mechanic way of seeing things.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] Re: Quad bag height adjustment [message #370099 is a reply to message #370096] |
Fri, 08 July 2022 20:02 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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On my '75, with the Power Level system, I run down the highway with the valves set to the "travel" position. I generally put them in "raise" whenever I travel on surface streets at lower than freeway speeds. This accomplishes two things; it decreases the caster on the front end, making steering easier, and it keeps the rear end from dragging when going in and out of driveways.
On an Electrolevel equipped coach, I would do the same thing only with the switches instead of the rotary valves.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| [GMCnet] Re: Quad bag height adjustment [message #370100 is a reply to message #370087] |
Fri, 08 July 2022 20:02 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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On my '75, with the Power Level system, I run down the highway with the valves set to the "travel" position. I generally put them in "raise" whenever
I travel on surface streets at lower than freeway speeds. This accomplishes two things; it decreases the caster on the front end, making steering
easier, and it keeps the rear end from dragging when going in and out of driveways.
On an Electrolevel equipped coach, I would do the same thing only with the switches instead of the rotary valves.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
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Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| [GMCnet] Re: Quad bag height adjustment [message #370109 is a reply to message #370087] |
Sun, 10 July 2022 01:06 |
Green machine
Messages: 184
Registered: July 2019
Location: North Vancouver BC
Karma: 5
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Brilliant answers folks. Thank you
--
Shawn Harris
North Vancouver,
Canada
1977 Palm Beach 403
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Shawn Harris
North Vancouver,
Canada
1977 Palm Beach 403
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| Re: [GMCnet] Re: Quad bag height adjustment [message #370113 is a reply to message #370096] |
Sun, 10 July 2022 11:56 |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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I have a 77 with EL-1 and the small air tank, but I have Hendrickson ride height valves.
My small tank will leak down in about 2-3 minutes. I can watch the gauge go down even in the HOLD position, but with no power to the pump the leak slows once it hits about 80psi. So to stop the pump cycling every few minutes I run in hold. I put it back to travel before getting underway after each stop. Of course anytime I decide to find the leak, it will hold pressure with no issues. The Hendrickson ride height valves likely don't have any delay which will cause the pump to run more.
I have an air pressure monitor system on our coach. I'll set the tires to 60psi in the morning before setting out when its about 20-22C out. If I forget to shut it OFF, its likely to wake me up in the middle of the night when the first tire hits 12% low, about 54psi and its about 15C outdoors. So I'm wondering if the increase in height your seeing is due to the air in the bag heating up. You set the ride height when its cooler in the morning, then the heat of the day, road, heat off the tires etc increase the bag pressure enough to make it rise.
Matt Colie wrote on Fri, 08 July 2022 12:41Bruce,
I may have identified another difference among coaches.
Chaum??re is a 73 23 that goes over the scale at 9460.
I have found that when we are in travel mode and running long hard days (we try to avoid that these days), the coach's handling gets strange if I
leave the air control in "Hold".
One of the times that I stopped for fuel with the control still holding, the rear was 1~1-1/2" (25~40mm) higher than I expected.
If I did not lock it out, the compressor would run about every hour.
I would not expect this to happen with the vast majority of coaches.
Matt
--
Matt & Mary Colie - Chaumi??re -'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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Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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