Air Bag measurement at ride height

Topic: Air Bag measurement at ride height (Read 1311 times) previous topic - next topic

Air Bag measurement at ride height

December 05, 2017, 07:59:08 pm

Hi Everyone
I know I saw it somewhere. I think it is 9"-9 1/4" or 9 1/2". I checked search. Didn't seem to find it.
Does anyone have the correct measurement for the air bags at ride height? From bottom plate to top plate. We had a metal gauge we made when I was at tech. I am going to make one
Thanks
Chris

Re: Air Bag measurement at ride height

Reply #1 – December 05, 2017, 08:09:47 pm

Chris, it's 8 1/4 + - from the top of the bottom plate to the bottom of the top plate.

Re: Air Bag measurement at ride height

Reply #2 – December 05, 2017, 08:17:15 pm

Chris I made a jig out of round stock to include top plate bag bottom plate 9-9 1/2. I run mine a bit taller than stock helps with bottoming out on some of our fine roads. I'll measure it in the morning.

Re: Air Bag measurement at ride height

Reply #3 – December 05, 2017, 08:50:59 pm

Quote from: rbark – December 05, 2017, 08:09:47 pm

Chris, it's 8 1/4 + - from the top of the bottom plate to the bottom of the top plate.

Thanks
Just to clarify. The bag plate, or the plate it bolts to over all?
Thanks

Re: Air Bag measurement at ride height

Reply #4 – December 05, 2017, 08:53:40 pm

I set at 8-1/2 overall, top of top plate to bottom of bottom plate.

Re: Air Bag measurement at ride height

Reply #5 – December 05, 2017, 08:55:00 pm

Quote from: bbeane – December 05, 2017, 08:17:15 pm

Chris I made a jig out of round stock to include top plate bag bottom plate 9-9 1/2. I run mine a bit taller than stock helps with bottoming out on some of our fine roads. I'll measure it in the morning.

That is what I have. 9 1/4" over all top of the plate it bolts to, to the bottom of the lower plate it bolts to.Seems easier to measure then the bags plates.
If you have the time, that would be cool.
Thanks a bunch
Chris

Re: Air Bag measurement at ride height

Reply #6 – December 05, 2017, 08:58:19 pm

Here is the whole enchilada.

ride-height-adjustment-in-motorhome-or-rv

Re: Air Bag measurement at ride height

Reply #7 – December 05, 2017, 08:59:42 pm

Quote from: craneman – December 05, 2017, 08:58:19 pm

Here is the whole enchilada. Rubber only to keep trailing arms correct.

ride-height-adjustment-in-motorhome-or-rv

Re: Air Bag measurement at ride height

Reply #8 – December 05, 2017, 09:11:45 pm

Here is a handy thread on the summary from Beamalarm.com on the subject of ride height adjustment;
ride-height-adjustment-in-motorhome-or-rv
I think the simplest place to measure it is between the frame members next to the air bags. The distance there is ideally 8 ½", or 8" between the air bag mounting plates since the mounting plates are ¼" thick. A template made in the shape of a "C" makes it easy to hold against the air bag and measure the span from the top of the top plate to the bottom of the bottom plate. Or, simply cut a stick or piece of pipe to 8 ½" and fit it next to the air bag. Since there are only three height control valves, two in the back and one in the front, there will likely be some averaging involved in the front measurements. I found this quote attributed to James Trianna, "According to James Trianna 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."
I just went through this when I changed out all three ride height valves at Bill C's warehouse and I did go through several evolutions with the adjustment. Essentially, setting the height of the front as close as I could come to having both side in the ball park, and then doing the back one side at a time, then redoing the front. rinse and repeat a couple of times. Then dumping the air completely and raising it completely and then letting it settle to ride height each time. I was able to get the backs almost dead on consistently, and after several tries the fronts were within a quarter inch of the desired measurement or within a half inch of each other. Since this was my first time doing this, it took a couple of tries to get the feel of it. I am sure next time will go a bit quicker.
Don

Re: Air Bag measurement at ride height

Reply #9 – December 06, 2017, 07:00:13 am

We had a problem with our ride height adjustment. Coming out of Three Flags in FL about 5 years ago I noticed that we just weren't sitting level. Stopped and looked under the left rear and sure enough, the rod showed some clean shaft while the rest had the usual road dirt. I loosened and adjusted and retightened and all was well. Checked when we got into the nest stop and all four corners were satisfactory.

Re: Air Bag measurement at ride height

Reply #10 – December 06, 2017, 08:39:08 am

Chris here is the "special tool" for the ride height. Also on my previous post I said 9 1/2" Sb 8 1/2" my bad. Currently that are set at 9" or so seams to help the bottoming out.

Re: Air Bag measurement at ride height

Reply #11 – December 06, 2017, 09:14:57 am

Please be aware that Bruce's ride height is not to Foretravel spec.

Not suggesting it will not work for him, but the Beamalarm link is the Foretravel recommended dimension/method and the one I use.

Re: Air Bag measurement at ride height

Reply #12 – December 06, 2017, 11:26:09 am

Quote from: bbeane – December 06, 2017, 08:39:08 am

Chris here is the "special tool" for the ride height. Also on my previous post I said 9 1/2" Sb 8 1/2" my bad. Currently that are set at 9" or so seams to help the bottoming out.

Thanks Bruce for taking the time to take pictures of the tool. I plan to make one too.
Chris

Re: Air Bag measurement at ride height

Reply #13 – December 06, 2017, 11:30:51 am

Quote from: wolfe10 – December 06, 2017, 09:14:57 am

Please be aware that Bruce's ride height is not to Foretravel spec.

Not suggesting it will not work for him, but the Beamalarm link is the Foretravel recommended dimension/method and the one I use.

Brett
We had a customer with a new 98 U270 ( Gene Reed) He owned the Subaru store here. He actually was a drag racer friend of mine. He had foam dice hanging in the windshield. Gene had us lower his coach an inch or two (can't remember). Looked pretty cool.
Chris

Re: Air Bag measurement at ride height

Reply #14 – December 06, 2017, 11:41:09 am

May look cool to take a coach out of ride height spec. But, be sure you are aware of its affect on shock travel (sure don't want to either hang an axle by the shocks or crush one on compression.

Also, consider drive line angles on that very short driveshaft.

Re: Air Bag measurement at ride height

Reply #15 – December 06, 2017, 11:57:56 am

Quote from: wolfe10 – December 06, 2017, 11:41:09 am

May look cool to take a coach out of ride height spec. But, be sure you are aware of its affect on shock travel (sure don't want to either hang an axle by the shocks or crush one on compression.

Also, consider drive line angles on that very short driveshaft.

Correct Brett, I wouldn't tell someone to do it. I believe he did have drive line issues, and we ended up raising it back up. He was one of the candidate's we had to add the counter weight to. I was the one to install it.
That is at a time when coaches were having rear bearing issues in the tranny's. I am pretty sure his went in to have that done. Been a few years.
His partner from the Subaru store, still owns the coach locally. I tried to buy it when I was looking last year. Jordan wouldn't part with it.
Merry Christmas
Chris

Re: Air Bag measurement at ride height

Reply #16 – December 06, 2017, 12:07:34 pm

Chris,

Counterweight to what?

Re: Air Bag measurement at ride height

Reply #17 – December 06, 2017, 12:38:54 pm

Quote from: wolfe10 – December 06, 2017, 12:07:34 pm

Chris,

Counterweight to what?

Counter weight, vibration dampener. Not all coaches had them. I installed a few. Ours has one.
Chris

Re: Air Bag measurement at ride height

Reply #18 – December 06, 2017, 05:55:16 pm

Thanks to everyone for all your help
Coach was 3/4" high in rear, 1 1/4" high in front. Previous owner carried a heavy motor bike on the front. He probably adjusted the front up.
At ride height, the coach checks level with a manual level (my shop is dead nuts level) I tweaked the level sensor slightly, because the rear low light still came on. It Previously did this, but when I hit auto level, the coach would drop 2-2 1/2"'s in the front.
As a bonus, I found another leak at the step valve.
Cheers
Chris

Re: Air Bag measurement at ride height

Reply #19 – December 06, 2017, 06:01:03 pm

What measurement did you end up using?

Re: Air Bag measurement at ride height

Reply #20 – December 06, 2017, 06:15:11 pm

Quote from: bbeane – December 06, 2017, 06:01:03 pm

What measurement did you end up using?

Bruce
I went with 8 1/2" overall on the mounting plates (8" between plates). Our coach is a 36'. It has the common slight (very slight) drive line harmonic vibration, between 68-74 MPH. I drive 62-65 MPH anyway that is the sweet spot for mileage (8 mpg).
I figure the lower the coach in the rear, the straighter the drive is. If it's the same (or worse bottoming out), I may do what you suggested, and raise it 1/2"
Chris

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