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Air bag replacement questions
I am in the process of changing front air bags and waiting for fittings to arrive. I have a few questions.
1) obviously i have the wheels off and the front of the bus supported at the rear of axle support points. I guess this means the axle is hanging from whatever establishes its travel limits. ( i dont even know what those components are but would like to) When i air up to test for leaks i assume no supports should be added near the end of the axles as this will raise the bus off of the support points. I just want to make sure it is ok to air up the bags with the axle hanging.
2) I will be changing the tag bags to the same Mae West bags next. But, it seems there could be a significant lead time for those right now. Could there be any issues with control or safety with the shorter bags on the rear and the taller on the front? My gut says no since the leveling valves will still maintain proper ride height but would like any thoughts.
3) Are DOT compression fittings required or recommended for our suspension or brakes only? I didnt see any DOT stamps on the fittings that came off and they do not look any different than what is used for water lines. They did have a thick interior brass thimble to support the interior of the tubing wall which i know must be used. Any info on requirements here would be appreciated.
Thanks in advance,
Jeff and Lindsay
91 Marathon XL -
16 Replies
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The shock absorbers limit travel, not sure what else does. We did not install the #630059 air bags on the tag axle and have not seen any issues.
1999 XLV X-6872, liberty #440 -
Thank you John. That helps a bunch.
1999 XLV X-6872, liberty #440 -
1. You want the axle hanging from the shocks to give you the most clearance to remove and install bags although I had to raise my drive axle for installation of the new bags because they weren’t stretched. I would be cautious about putting max air pressure in with axle hanging. Can you put jackstands under axle when you inflate?
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2. Can’t imagine this would be a problem.
3. I ALWAYS replace with dot compression fittings.
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I have done about every combination of things possible regarding raising and lowering the chassis with air bags, raising it with the wheels on the ground, having it raised with wheels off, driving it with the air bags all the way up or down, and any combination of the above.
I have ALWAYS supported it on stands with the chassis raised often when it is only in storage waiting for the next trip. I have had it raised and supported and removed all the wheels so the suspension was letting the axles hang.
I have raised it, and then jacked up an axle to remove wheels.
Nothing I have done has ever done any damage. The only caveat is I never allow the coach air system to exceed 120 PSI. That pressure is the only limit to what I do.
I have replaced air bags on three of my coaches at least once each coach. I have replaced shocks, not of which were damaged by putting as much as 120 PSI in the air bags and then driving up or down my driveway. My point being I may be wrong, and may be exceeding all kinds of limits, but over a 30 year period I am not aware of any damage I caused to any of my coaches.
Have at it. Do whatever you want and do not worry about it, but never ever put any part of your body under a coach or between parts of the coach unless it is supported at the chassis support points.
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Thanks you guys for the information.
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Just finished both drive axle bags replace today. First one took @ 3 1/2 hrs , second took about 2 hrs. Replaced push fittings with compression..
Pics below depict my process. Safety first !
Drive tires not removed. Pipe thread not teflon tape used. Fender cover removed for clearance.
Bags were compressed using ratchet straps for easy installaton .
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try compressing bag by hand then put pipe plug in top of bag before releasing pressure= partially collapsed bag. remove plug when in position bag grows in place.
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Will try that on other four next week. Thanks Robert.
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
Looks good. Are you concerned about not having a mounting nut on the combo air tap/ stud? Thanks.
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DP
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Never have the hydraulic jack used for support have the piston extended. It could fail. Just leave it all the way down and extend the center screw post.
As to collapsing air bags, those cheap ratchet straps work great to hold the air bag collapsed and if you don’t let the bottom threaded bolts drop into the holes you can release the ratchet, pull out the hook and then give the air bag a little twist to drop it into the holes.
Be careful not to tighten the bottom air bag nuts too tight. The bottom can is pretty thin and too much torque can crack the bottom can near the threaded bolt. I use nylok type nuts, tightened a little. They will not unscrew themselves.
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On the brass and compression fitting do you use just teflon tape or?
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Yes on the tape.
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white tape has leaked on mine..Peter said use Gray some years back ..he was correct. Never use tape on sensor thread=doesn’t let sensor ground and read correctly–been there on this one also. Bob
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