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Topic: Max Raised Height Problem (Read 551 times) previous topic - next topic

Max Raised Height Problem

I recently completed replacing my 4 air tanks.  Today I started getting the coach ready for a camping trip tomorrow.  I raised the height all the way and took out the 4 safety stands in the back but the 4 in the front were stuck.  The front of the coach would not raise high enough to get the stands out.  I checked the front air regulator and it was set on 60 psi.  I don't see anything amiss or hear any leaks.  Before raising the coach the air pressure had held steady at ~75 psi for almost 48 hours in the front and rear tanks (that's pretty cool).

I got the stands out using a hydraulic jack next each stand.  I adjusted the front regulator to 80 psi and was able to achieve another 1/2" in height.  Raised it to 100 psi and got maybe another 1/2".  I now have about 1/4" height more than when I originally put the stands in place.  So, the airbags will raise the coach but only with the regulated pressure much higher. 

Any ideas?
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #1 –
Mark,

Please measure ride height and let us know what it is at each wheel position.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Max Raised Height Problem

Reply #2 –
Quote from: wolfe10 –
Mark,

Please measure ride height and let us know what it is at each wheel position.
Brett,

Measuring from ground to flat part of wheel well above tires.  In travel mode:

LF 41.5
RF 40.5

LR 41.5
LT 41

RR 41.5
RT 41
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #3 –
Measure the height between the top and bottom plates of the air bags.

Most Foretravels have the proper ride height spec written down on the underside of the dash lid (if the dash flips up).

For a quick comparison I'll sometimes set a large adjustable slide/wood clamp to the proper measurement and use that to check the distance between airbag plates.

Chris

Re: Max Raised Height Problem

Reply #5 –
RIGHT FRONT
Front Bag 8-1/4"
Rear bag  8-3/8"

LEFT FRONT
Front Bag 9-1/4"
Rear bag  9-1/2"

LEFT REAR
Front Bag 9-1/2"
Rear bag  8-7/8"

RIGHT REAR
Front Bag 9-3/4"
Rear bag  9-1/8"
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #6 –
Just now reading through the info from reply #4 above.  I measured between the from the top of the top plate to the bottom of the bottom plate so each measurement above is probably 1/4" too thick.  In other words 1/4" or so will need to be subtracted from each measurement.
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #7 –
Is the coach on a level spot?  Don't adjust ride height without it being so.

Also, once you free the supports, put the regulator back at 65 psi - that's what it's supposed to be to keep the front from airing up too fast compared to the rear.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Max Raised Height Problem

Reply #8 –
Quote from: Michelle –
Is the coach on a level spot?  Don't adjust ride height without it being so.

Also, once you free the supports, put the regulator back at 65 psi - that's what it's supposed to be to keep the front from airing up too fast compared to the rear.
At the moment it is not on a level spot.  It's parked behind our warehouse and the pad back there is sloped to a central drain.  I was just sitting here pondering where I can find a level spot of pavement. 
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #9 –
Are there any DOT truck scales in the area?  Some states have them along highways open to the public.

Chris

Re: Max Raised Height Problem

Reply #10 –
Mark,
60 psi will raise the front up to the maximum height. Increasing air pressure to raise it more really makes me think you may have a pressure regulator problem.
Just a long shot but think I would check that nothing went down that air line from your tank changes that is restricting air flow into the regulator. If nothing in there I would replace the regulator.
They are not expensive and it's probably getting old anyway.
John Duld
1995 U320C SE 40'

Re: Max Raised Height Problem

Reply #11 –
Quote from: John Duld –
Mark,
60 psi will raise the front up to the maximum height. Increasing air pressure to raise it more really makes me think you may have a pressure regulator problem.
Just a long shot but think I would check that nothing went down that air line from your tank changes that is restricting air flow into the regulator. If nothing in there I would replace the regulator.
They are not expensive and it's probably getting old anyway.
John,

Recently installed a new regulator.  I'll check for an obstruction.

Thanks,
Mark
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #12 –
Mark,

When measuring ride height, measure at the bags toward "center" of coach-- so  bags behind the front wheels for front and bags in front of the wheels for rear.

When you get it to level ground, set rear ride height first because it is the only side to side adjustment.

Then level front so that left and right "average" the correct height (only one ride height valve in front.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Max Raised Height Problem

Reply #13 –
I was studying my air system schematic and checking the newly installed tanks looking for an error when I decided to exercise the system a little and see what happened.  Lo and behold, after 2 cycles of raise and dump, the new protection valves or check valves sounded very different.  Hard to explain but the sound they make when the air passes through them is different than earlier today.  Now -- with the front air regulator reset to 60 psi -- all is well.  The safety supports can go in and come out.

I'm not a big fan of problems that self-resolve without a solid explanation, but in this case I'd love to make an exception.  Do you think we might chalk this up to the all the new check valves and protection valves being a bit stiff???

From the earlier measurements, it looks like my ride height might be off a bit but I need to get to a level surface to double check.
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #14 –
Quote from: Numbers –
Are there any DOT truck scales in the area?  Some states have them along highways open to the public.

Chris
Hey Chris.  Not sure but I'll check it out.
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #15 –
Quote from: Numbers –
Measure the height between the top and bottom plates of the air bags.

Most Foretravels have the proper ride height spec written down on the underside of the dash lid (if the dash flips up).

For a quick comparison I'll sometimes set a large adjustable slide/wood clamp to the proper measurement and use that to check the distance between airbag plates.

Chris
I have a couple of those.  Great idea to use it that way.  Thanks!
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Max Raised Height Problem

Reply #16 –
Quote from: Mark Duckworth –
I was studying my air system schematic and checking the newly installed tanks looking for an error when I decided to exercise the system a little and see what happened.  Lo and behold, after 2 cycles of raise and dump, the new protection valves or check valves sounded very different.  Hard to explain but the sound they make when the air passes through them is different than earlier today.  Now -- with the front air regulator reset to 60 psi -- all is well.  The safety supports can go in and come out.

I'm not usually a fan of problems that self-resolve without a solid explanation, but in this case I'd love to make an exception.  Do you think we might chalk this up to the all the new check valves and protection valves being a bit stiff???

From the earlier measurements, it looks like my ride height might be off a bit but I need to get to a level surface to double check.

One of the much beloved shops in Nac shared with me that "trash" (dirt/debris) can get into the air system during replacement of air components and can sometimes get stuck in items like solenoids, and cause problems.

The remedy they shared with me was that cycling the air system a number of times can often clear the system out when dumping the air.

Chris

Re: Max Raised Height Problem

Reply #17 –
Quote from: Numbers –
One of the much beloved shops in Nac shared with me that "trash" (dirt/debris) can get into the air system during replacement of air components and can sometimes get stuck in items like solenoids, and cause problems.

The remedy they shared with me was that cycling the air system a number of times can often clear the system out when dumping the air.

Chris

That certainly makes more sense than my guess!
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971