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Topic: Ride height failure (Read 1077 times) previous topic - next topic

Ride height failure

No sooner did  we solve the coolant loss problem, when I found that the top of my LR wheel well was resting on top of the dualies when doing the final test ride on previous issue.
We have the Wabco height adjuster and new Contitech airbags (replaced in 2017).  I looked at the adjuster and could not find any damage or sign that it came loose.  The only observable issue, other than deflated bag in travel mode is a crack in the rubber boot at the bottom of the unit.

Is this a question of trying to make  an adjustment or is it a failure of the unit?
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8

Re: Ride height failure

Reply #1 –
Possibly your left rear travel mode air solenoid.
Doug W.
96 36' U270 CSGI #4946
04 Toyota Tacoma 4x4
PNW

Re: Ride height failure

Reply #2 –
It looks like "TheBrays" had this problem a couple  of years ago.  Great write up.  I'm leaning toward ordering three new height adjusters, unless someone thinks it could be something else.
Travel Mode Air Problem
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8

Re: Ride height failure

Reply #3 –
Sevn,
Do you have air exhausting?
Where is the air exhausting from?
Is it coming out of the bottom of the ride height valve?
    If here check linkage or replace bad valve
Is it exhausting out the exhaust port on the 6 pack?
  If here service rear travel mode air solenoid on the rear 6 pack

If no air exhausting are you getting air to this sides ride height valve?
If this is the case then look at rear travel mode air solenoid on the rear 6 pack like has been mentioned.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Ride height failure

Reply #4 –
[quote The only observable issue, other than deflated bag in travel mode is a crack in the rubber boot at the unit.


Is the air bag cracked?  No rubber boot on my coach only the folded bag when completely deflated.
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Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: Ride height failure

Reply #5 –
What Mike said.  ^.^d
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Ride height failure

Reply #6 –
After reading previous posts and the "horror" of having a failure on a trip, I decided to order three new adjusters.  The boot I was referring to earlier was the rubber cap at the bottom of the adjuster.  I managed to finally level the coach using plywood under wheels and may check for exhausting air tomorrow. 
My air bag is a little different than the one represented in a photo in Beamalarm in that the "piston" (base) is wider.  I'm assuming that the 8" travel length still applies.  In the photo, the air bag is at full extension and my wood and nail scale is 8 1/2"
As with everything else that has gone wrong, this has been a learning experience. 
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8

Re: Ride height failure

Reply #7 –
Sven,

Not sure "total lift" is important.

What is the measurement on level pavement with suspension in "travel mode"?

That is really the relevant measurement.
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: Ride height failure

Reply #8 –
Quote from: Sven and Kristi –
In the photo, the air bag is at full extension and my wood and nail scale is 8 1/2"
Sven,

It sounds like you may be a little unclear about how and where the "ride height" measurement is taken.  Don't feel bad - every time the subject comes up I get confused.  I have bookmarked a quote from a old post by Forum member Rudy, which never fails to help me get my mind right.  Have copied it below:

Air bags have a quarter inch plate on the top and bottom of each bag.  Sort of like a Oreo cookie with the bag being the filling and the plates being the cookies on the top and bottom of the filling.

Place your motor home on as level a slab as you can find, engine running, "TRAVEL" light "ON", air system at normal pressure.

To measure the ride height one must choose one of two measurements.  Measure from the top of the top plate to the bottom of the bottom plate, which should be 8.5 inches.

Or, measure from the top of the bottom plate (where the bag sits on the plate) to the bottom of the top plate (where the plate sits on the bag), which should be 8 inches.

In short, the measurement including the bag and the plates is 8.5 inches or the measurement of just the bag is 8 inches.

Adjust the two rear height adjustments first.  This should give them the correct height and the side to side measurement should be the same.  Then adjust the single ride height for the front.

I hope this helps you.

Rudy Legett
1995 U320
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Ride height failure

Reply #9 –
 I think that most of our measurements have been from plate to plate .  But FWIW it appears that your bag pic shows the bag about 1 in too high, judging by the exposed bottom cup .
  My chassis is early and the plate to plate is near 11in if i recall.

Re: Ride height failure

Reply #10 –
Rudy,  there is a good write up about it in the Beamalarm tech section that describes this.  My air bag assembly includes the top and bottom plate and a 2 3/4" concave section (see photo) that is metal between the bag and bottom plate.  If I measure between the  top of the top plate and bottom of the bottom plate (8 1/2"), will that include the 2 3/4" beneath the bag?  If I don't include the 1/4" plates will the 8" be for the rubber part of the bag or the bag plus the concave section?
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8

Re: Ride height failure

Reply #11 –
Sven,

Rudy isn't here today (except in spirit) - I'm just quoting him.

The concave metal section that you are talking about is part of every bag, and is hidden from view when the coach is down at normal ride height.  What is important is the measurement described above.  The hidden part of the metal bag "base" doesn't enter into the equation.

EDIT:  OK, I just went out and looked at our air bags, which I just happen to have at full extension because I'm working on the coach.  Now I see what you are talking about!  Your bags ARE different from the ones on our coach, with a somewhat "taller" metal base where the bottom of the bag is attached.

BUT, I still think your "ride height" measurement will have to be the same as any other coach, or else your suspension and drive shaft alignment will be incorrect.  However, I could be wrong...

Where did you get those air bags?  Do they have a part number on them anywhere?
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Ride height failure

Reply #12 –
Sven,
Think about it like you are putting 8.5" safety stands right next to the air bags. That rectangular tubing the the round plates are welded to should be 8.5" apart when at ride height on level ground. When I put in new ride height valves, I made an 8.5" spacer out of a piece of pipe and a flange to put right next to the air bag. With the linkage loose, I rotated the valve until the weight was just starting to come off of the spacer, then tightened up the linkage. I had to tweak it a couple of times to get it just right because there are variables in how the sections of the linkage meet up. The rule of thumb, as I recall, is to have the long vertical section nearly straight up and down at ride height. Changing the relationship between the rods affects how the valve responds to suspension movement. The 8.5" spacer also acted as a safety measure in case of a miscalculation. The rears may be able to be adjusted from outside the coach, but the front requires you to be underneath unless you want to put it up in the air with stands, tweak the adjustment slightly, take the stands out, start it up and put it in travel mode, measure each of the fronts. If the measurement is off, rinse and repeat. That was just the method I used, you can decide if that can work for you. Ride height adjustment is one case (of many!) where a pit would be sooo nice to have. One additional note... at ride height, the valve should be in the neutral position so that a slight movement of the suspension doesn't dump or add air. This procedure is in the instructions that come with the new valve.
Below is the part number I used and a quote attributed to James Trianna of FOT:
Quote
Ride Height Valves and Adjustment info
HALDEX Midland p/n: KN27000 - Type EGP - An Immediate Response Height Control Valve w/Linkage Kit, Valve only, KN2700
Notes: According to James Trianna (from post on the forum) the anchored rod should be vertical when the coach is in travel mode and the air spring measures 8.5" from the top of the top plate to the bottom of the bottom plate. The anchored rod vertical adjustment is achieved by repositioning the control lever in or out. Additionally,  measurements should be taken at the bags behind the front wheel and in front of the rear wheels. He recommended starting at the front air bags.
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Ride height failure

Reply #13 –
Another way of looking at the dimension of "top of top plate to bottom of bottom plate" (8.5") it that this is exactly the same as measuring between the horizontal beams to which the plates are attached.
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: Ride height failure

Reply #14 –
Quote from: Sven and Kristi –
Rudy,  there is a good write up about it in the Beamalarm tech section that describes this.  My air bag assembly includes the top and bottom plate and a 2 3/4" concave section (see photo) that is metal between the bag and bottom plate.  If I measure between the  top of the top plate and bottom of the bottom plate (8 1/2"), will that include the 2 3/4" beneath the bag?  If I don't include the 1/4" plates will the 8" be for the rubber part of the bag or the bag plus the concave section?

Your 8-1/2" nail scale should cover plate to plate......... top nail on top of the top plate and bottom nail to the bottom of the bottom plate. Yes it appears that you have the bags full extended which exposes the concave surface the bags rest in when in travel mode.

Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Ride height failure

Reply #15 –
Maintaining the 8.5" distance between the beams makes sense, regardless of the actual size of the bag, so the bag should not be measured for my purposes.  I like your idea of having the spacers, Don, and I will have some 2"x8.5" square tubing cut for that purpose.  I installed a compartment behind the LR dualies, so can't access the adjuster without getting under the rig.  Since I can't use my normal 11.5" blocks for safety, these will serve that purpose and act as a gauge when making the adjustment.  Thanks for taking the time to make the response (I did read your earlier post, describing the procedure). 
I will have to delay this project until after we get back from Mammoth where we have another that has to be done before the cold weather and then when we get back, it will be the RV barn.  It looks like our extended trip to the east coast will be impacted by the recent announcement that we will be having our first grandchild in early April - For some reason, Kristi just has to be here for that  :D
Craneman, take notice - even in retirement......
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8
 

Re: Ride height failure

Reply #16 –
I also put a compartment made out of welded ⅛" aluminum sheet in that location. I used a six inch hole saw in the rear of the compartment and bought a stainless steel door kick plate bought at the local big box store to make a cover. I located the hole adjacent the ride height valve to facilitate removal and replacement of the leaking left rear ride height valve, but plan on adding another access hatch adjacent to the top of that air bag to facilitate ride height adjustment. The kick plate is probably 22 gage and I cut it in half so that it would make two covers. It was sort of an ad hoc operation because I did it at a campground in Colorado. The left rear was riding way too low for comfort and I found a Napa that that stocked the valves. I bought three, but just replaced the left rear one at the campground and did a very rough adjustment of the new valve. It was a big improvement! Later in that trip, I did a more precise adjustment at Bill C's warehouse where I replace the other valves and had really nice, very flat and level concrete pad.
Don
Quote from: Sven and Kristi –
I installed a compartment behind the LR dualies, so can't access the adjuster without getting under the rig.  Since I can't use my normal 11.5" blocks for safety, these will serve that purpose and act as a gauge when making the adjustment.  Thanks for taking the time to make the response (I did read your earlier post, describing the procedure). 
Craneman, take notice - even in retirement......
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson