Home » Public Forums » GMCnet » [GMCnet] Ride Height
| [GMCnet] Ride Height [message #345740] |
Thu, 25 July 2019 20:07  |
glwgmc
Messages: 1014
Registered: June 2004
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No need for an electronic way to measure ride height as the hysteresis in most GMC suspensions keeps it from changing all that much in use. Set your coach to proper ride height (block the rear at proper ride height, set the front and then drive the coach a few miles and recheck ride height front and rear until it is proper front and rear after your drive. Now, measure the air pressure in the rear air bags. When you are about to leave on a trip, put that much air in the rear bags and boogie on. You will find few coaches need anything more than that. KISS is very much your friend here.
Jerry
Jerry Work
Kerby, OR
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Ride Height [message #345743 is a reply to message #345740] |
Thu, 25 July 2019 20:52  |
Rob
Messages: 651
Registered: November 2013
Location: Victoria, BC
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I get major differences at the same pressure based on my load, mainly due to occasionally carrying a large-ish scooter on the rear bumper. I also vary quite a bit from empty to full of fuel and water.
In my case - I really need at least 3 or 4 pressures for various loads - but the Wireless Air only has two presets... Right now - I keep preset one at 70 PSI and preset two at 75 PSI - which lets me quickly get to any 5 or 10 PSI number...
Being able to quickly measure my rear height from inside would be great - but finding time to finish the project gets in the way of camping... Having an Raspberry Pi and two ultrasonic sensors is pretty simple - basically an electronic ruler...
Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath
> On Jul 25, 2019, at 6:07 PM, Gerald Work via Gmclist wrote:
>
> No need for an electronic way to measure ride height as the hysteresis in most GMC suspensions keeps it from changing all that much in use. Set your coach to proper ride height (block the rear at proper ride height, set the front and then drive the coach a few miles and recheck ride height front and rear until it is proper front and rear after your drive. Now, measure the air pressure in the rear air bags. When you are about to leave on a trip, put that much air in the rear bags and boogie on. You will find few coaches need anything more than that. KISS is very much your friend here.
>
> Jerry
>
> Jerry Work
> Kerby, OR
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Rob -
Victoria, BC -
76 Royale - Rear Twins/Dry Bath
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| Re: [GMCnet] Ride Height [message #345746 is a reply to message #345743] |
Thu, 25 July 2019 21:19 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Redundancy is great in spacecraft. So not neccessary in 40 year old
coaches. Kinda like putting lipstick on a pig. Do what you will, it is
still a pig. But, what the heck, it's your money, spend it how you see fit.
Jim Hupy
Salem, Or
On Thu, Jul 25, 2019, 6:53 PM Rob via Gmclist
wrote:
> I get major differences at the same pressure based on my load, mainly due
> to occasionally carrying a large-ish scooter on the rear bumper. I also
> vary quite a bit from empty to full of fuel and water.
>
> In my case - I really need at least 3 or 4 pressures for various loads -
> but the Wireless Air only has two presets... Right now - I keep preset one
> at 70 PSI and preset two at 75 PSI - which lets me quickly get to any 5 or
> 10 PSI number...
>
> Being able to quickly measure my rear height from inside would be great -
> but finding time to finish the project gets in the way of camping... Having
> an Raspberry Pi and two ultrasonic sensors is pretty simple - basically an
> electronic ruler...
>
> Rob
> Victoria, BC
> 76 Royale - Rear Twins/Dry Bath
>
>> On Jul 25, 2019, at 6:07 PM, Gerald Work via Gmclist gmclist@list.gmcnet.org> wrote:
>>
>> No need for an electronic way to measure ride height as the hysteresis
> in most GMC suspensions keeps it from changing all that much in use. Set
> your coach to proper ride height (block the rear at proper ride height, set
> the front and then drive the coach a few miles and recheck ride height
> front and rear until it is proper front and rear after your drive. Now,
> measure the air pressure in the rear air bags. When you are about to leave
> on a trip, put that much air in the rear bags and boogie on. You will find
> few coaches need anything more than that. KISS is very much your friend
> here.
>>
>> Jerry
>>
>> Jerry Work
>> Kerby, OR
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] Ride Height [message #345747 is a reply to message #345746] |
Thu, 25 July 2019 21:34 |
Rob
Messages: 651
Registered: November 2013
Location: Victoria, BC
Karma: 3
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It's less about redundancy (for my calibrated height measurement stick) and more about convenience. $49 ($35 for a Raspberry Pi and $14 for two sensors) isn't really enough to get too worried about...
I guess $49 would buy a lot of rulers - but one instance of not having to measure the height outside in the rain would more than make up for the difference (IMO)...
Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath
> On Jul 25, 2019, at 7:19 PM, James Hupy via Gmclist wrote:
>
> Redundancy is great in spacecraft. So not neccessary in 40 year old
> coaches. Kinda like putting lipstick on a pig. Do what you will, it is
> still a pig. But, what the heck, it's your money, spend it how you see fit.
> Jim Hupy
> Salem, Or
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Rob -
Victoria, BC -
76 Royale - Rear Twins/Dry Bath
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| Re: [GMCnet] Ride Height [message #345750 is a reply to message #345747] |
Thu, 25 July 2019 23:12 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Just because we CAN build the great pyramids using forced slave labor,
notched sticks, knotted papyrus reeds crafted into string, and barges to
float the huge stones from the quarry to the job site, doesn't mean we have
to do it that way today.
Heavy lift cranes, laser measuring instruments, motorized moving
equipment, etc. all make the job much easier, particularly the forced slave
labor part. What is my point, you might ask?
Well, sometimes we get caught up in all the stuff available to us now,
and lose sight of the final task. Which is getting the front ride height
correct to prevent stuff like excessive nose deflection upon heavy braking,
unloading the rear most wheels and flat spotting the tires as a result.
Rear ride height changes while underway are difficult to tell much about
before they change again. Get the front absolutely correct, the rear? Good
luck.
Jim Hupy
Salem, Oregon
On Thu, Jul 25, 2019, 7:35 PM Rob via Gmclist
wrote:
> It's less about redundancy (for my calibrated height measurement stick)
> and more about convenience. $49 ($35 for a Raspberry Pi and $14 for two
> sensors) isn't really enough to get too worried about...
>
> I guess $49 would buy a lot of rulers - but one instance of not having to
> measure the height outside in the rain would more than make up for the
> difference (IMO)...
>
> Rob
> Victoria, BC
> 76 Royale - Rear Twins/Dry Bath
>
>> On Jul 25, 2019, at 7:19 PM, James Hupy via Gmclist gmclist@list.gmcnet.org> wrote:
>>
>> Redundancy is great in spacecraft. So not neccessary in 40 year old
>> coaches. Kinda like putting lipstick on a pig. Do what you will, it is
>> still a pig. But, what the heck, it's your money, spend it how you see
> fit.
>> Jim Hupy
>> Salem, Or
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] Ride Height [message #345752 is a reply to message #345750] |
Thu, 25 July 2019 23:42 |
Rob
Messages: 651
Registered: November 2013
Location: Victoria, BC
Karma: 3
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Senior Member |
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I'm not too worried about what my ride heights are underway - I have little control over that. But I do like *trying* to have my rear ride height semi-correct before I start driving. Since I have a Wireless Air and dramatically varying rear loads - I have to manually check my heights. I suppose I could just *hope* they're good - but I'd prefer to measure them and I don't see $49 being a big deal... Cheap compared to almost anything else that can be done to a GMC...
I don't have the tools to get the front heights adjusted - and my location means there are very few options for having it done for me... That may change at some point - but not before my next trip!
Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath
> On Jul 25, 2019, at 9:12 PM, James Hupy via Gmclist wrote:
>
> Just because we CAN build the great pyramids using forced slave labor,
> notched sticks, knotted papyrus reeds crafted into string, and barges to
> float the huge stones from the quarry to the job site, doesn't mean we have
> to do it that way today.
> Heavy lift cranes, laser measuring instruments, motorized moving
> equipment, etc. all make the job much easier, particularly the forced slave
> labor part. What is my point, you might ask?
> Well, sometimes we get caught up in all the stuff available to us now,
> and lose sight of the final task. Which is getting the front ride height
> correct to prevent stuff like excessive nose deflection upon heavy braking,
> unloading the rear most wheels and flat spotting the tires as a result.
> Rear ride height changes while underway are difficult to tell much about
> before they change again. Get the front absolutely correct, the rear? Good
> luck.
> Jim Hupy
> Salem, Oregon
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Rob -
Victoria, BC -
76 Royale - Rear Twins/Dry Bath
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| Re: [GMCnet] Ride Height [message #345757 is a reply to message #345740] |
Fri, 26 July 2019 07:41 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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I keep reading here that the elevation control (ride height) does not do much. I guess I don't care very much what others think and how much they can feel. I do know two things as facts.
If we stop to take on fuel, that is typically ~300# (45~48gal), when we restart, the compressor usually runs.
When we had a bad cab control valve that leaked air into the system, it would not be long before one could feel the change in handling.
Admittedly, we have a much lighter coach than most and as a refugee from automotive testing and car racing, I am likely to be more sensitive. For as little work as it takes to keep the system working as designed, I just don't think it is a good thing to ignore.
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: [GMCnet] Ride Height [message #345761 is a reply to message #345757] |
Fri, 26 July 2019 09:12 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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Those frequent adjustments of the stock system drove me crazy, they definitely do change the behavior of the coach.
One other interesting thing about the ride height system is the sensors are on the drivers side rear and pass side front. this means of the ground isn't perfectly level when you are calibrating it will through the heights off a lot more than you expect as one wheel is lower and the the other is higher than you think
Microlevel has less hysteresis than the stock system, it also doesn't adjust as often so it doesn't change heights on a cloverleaf and then again afterwords so the coach feels more stable in turns and crosswinds.
Calibration is easier also as the height sensors have zero hysteresis and the controller knows the actual height of the coach. No need to drive around after setting height
Keith
________________________________
From: Gmclist on behalf of Matt Colie via Gmclist
Sent: Friday, July 26, 2019 7:41 AM
To: gmclist@list.gmcnet.org
Cc: Matt Colie
Subject: Re: [GMCnet] Ride Height
I keep reading here that the elevation control (ride height) does not do much. I guess I don't care very much what others think and how much they can
feel. I do know two things as facts.
If we stop to take on fuel, that is typically ~300# (45~48gal), when we restart, the compressor usually runs.
When we had a bad cab control valve that leaked air into the system, it would not be long before one could feel the change in handling.
Admittedly, we have a much lighter coach than most and as a refugee from automotive testing and car racing, I am likely to be more sensitive. For as
little work as it takes to keep the system working as designed, I just don't think it is a good thing to ignore.
Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
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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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