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Max Bag Height Full Extension

When fully raised my rear air bags measure 13" plate to plate. My front bags measure 10 1/4" fully extended. Is that normal or a problem
2001 4010 U320
Build 5875

Re: Max Bag Height Full Extension

Reply #1 –
That seems low. Most of us are using 11" or 12" safety blocks between the frames. I had a similar problem in the back until I replaced the four leaky bags back there. Have you sprayed them with bubble solution yet to check for leaks?
1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Max Bag Height Full Extension

Reply #2 –
New bags. Chased and repaired major leaks. New D2, safety valves, etc.. Just won't lift front past that height. Not leak at this point.. Wondering if there is some type of high limit setting on each axle and if should be concerned. Had hard time getting my blocks out from front. Been on blocks for 5 weeks
2001 4010 U320
Build 5875

Re: Max Bag Height Full Extension

Reply #3 –
I believe it's the shocks that limit the height extension.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Max Bag Height Full Extension

Reply #4 –
You say "new bags".  Did you replace all bags, or just the front bags?  If you replaced all bags, are they all the same make/model/part number?

What is your max system air pressure when the compressor cuts out?

What pressure is set on the pressure regulator mounted up front in the vicinity of your two front air tanks?
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: Max Bag Height Full Extension

Reply #5 –
What's the air pressure on the regulator for the front air bags?
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: Max Bag Height Full Extension

Reply #6 –
Quote from: Spiderhitch –
When fully raised my rear air bags measure 13" plate to plate. My front bags measure 10 1/4" fully extended. Is that normal or a problem
Air bag "length" when fully extended should be the same front and rear.

What do you mean by "plate to plate"?  What plates?  Where exactly are you making those measurements?

With air bags fully extended, you should have around 12.5" to 13" between the upper and lower frame members immediately inboard from the top and bottom air bag mounts.  This will allow, on most coaches, the easy insertion of 12" long safety stands with a little extra room to spare.

How long are your safety stands?

What procedure do you use to raise your coach?  It is possible you are not allowing enough time for the coach to raise fully.

Link below to a thread where we discussed this subject:

Safety Stand Placement
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: Max Bag Height Full Extension

Reply #7 –
All bags replaced with new Contitech bags November. Just replaced leaking pressure gauge at front tank and safety gauges at both front tanks. All new fittings on manifolds at tanks and new drain valves at front tank and wet tank. New safety gauge at wet tank 150#. New D2 set to 125# hi limit. Measuring bags from top of plastic (?) Mounting plate of bag to bottom plate of bag. Front pressure gauge was set to 120# i believe. I left it fully pumped for weekend with no stands. Will see how much lost Monday. I don't have metal spacers yet. I was using 6x6 blocking. When raising i use the raise switch just above dump. Tried several times and held long enough for lift.
2001 4010 U320
Build 5875

Re: Max Bag Height Full Extension

Reply #8 –
The attached chart for Firestone bags show Pressure vs. load vs. height.
I would try to find the same info for the Conti bags.
I'm not completely sure why the regulator is there but if set at 120 PSI that's too high IMO; I think I read something about the risk of ripping the top bead seal on the bag if overextended/over inflated. (Found it: it's on page 214 of 218 on the 2000 edition of the Firestone Catalog)

Another tidbit of information: or my older coach with manual air leveling the instructions do have a warning (skip to the end) about not exceeding 12.5 inches. But that is for Firestone bags.  Note the chart in the Firestone Design document on where height is measured.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: Max Bag Height Full Extension

Reply #9 –
My bags are probably about 12.5" on rear my measurements are from top to bottom of mounting plates. Each are approx. 1/4" thick
2001 4010 U320
Build 5875

Re: Max Bag Height Full Extension

Reply #10 –
The front 6-pack pressure regulator should be set to 60-70 psi.
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: Max Bag Height Full Extension

Reply #11 –
I suspect you have a air leak.
Sometimes you have to raise them up individually instead of using the raise all button. I always have trouble getting my rear stands out until twig showed me another way of raising coach for that purpose. Start the engine and run the pressure up to 120 then shut off the engine. Take the key out. Raise your rear until it smacks and then shut it off and go out and put your stands in then raise the front shut it off and I'll put your stands in and then lower it so they're all supported. You can use the dump button to lower it. That work better for me the last time.
'99 U320 40 WTFE
Build #5462,
1500 Watts Solar 600 amp Victron lithium
2012 Jeep Grand Cherokee Overland Hemi
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Retired