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Old 07-14-2019, 10:25 AM   #1
4 Rivet Member
 
1986 34.5' Airstream 345
Londonderry , New Hampshire
Join Date: Mar 2017
Posts: 252
Changing my air bags.

I wanted to change my 33 year old air bags. I finally attacked the
job. Here is the first one:
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The top:
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The bottom:
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I have a new set of air bags on order. The job was not too bad.
The bottom bolt was not seized, it seemed to have anti-seize compound
on the threads.


The bolts on the top were difficult to get to but there is enough room
to get a socket and a breaker bar in there. With lots of pulling and
tugging I got them out. They are 9/16 inch bolts which is good to
know since you can't see them.


Mine were rusty and a 9/16 12 point socket slipped on them. They
were rusted a little smaller. I could get a 14MM 6 point socket on
them and then I could break them loose.


I think that while the air bags are out I will replace the air lines.
I have heard that some of the modern industrial push on plastic
lines work well. Anyone have any suggestions?


While I am at it I may install a pressure gauge to measure the
air bag pressure. I always like to know what is going on with
the systems.


While I was in there I pulled my tag axle brake drum:
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Clearly the electric brakes have problems.
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Old 07-14-2019, 01:23 PM   #2
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1982 28' Airstream 280
Port Angeles , Washington
Join Date: Aug 2008
Posts: 1,916
Let me start by saying...I love Never Seez. The stuff is great.

I used DOT approved brake tubing with push on fittings on my air ride tag axle installation. They work great and are easy to work with. Just make sure your tubing cuts are clean and square.

I run a bag pressure gauge on the dash. It is a double gauge, one needle shows drive axle bag pressure and the other shows tag axle bag pressure. It's interesting to watch them bounce as you go over imperfections on the road surface.

The drive axle bags run around 75 psi. Having air pressure available up front, I added a small pressure regulator and plumbed it to the front air bags in the coil springs. It is set at 55 psi so the front bags are properly inflated anytime the coach is running.

I feel many tag axle brakes are in a similar condition. The magnet wires were broken on both sides on my coach and looked like they had been that way for some time.
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Old 07-16-2019, 07:13 PM   #3
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1987 34.5' Airstream 345
Menomonee Falls , Wisconsin
Join Date: Jul 2010
Posts: 418
Hey,
I did a post I think may 15 2017 on doing my airbags on our 325. I changed over to all push on air fittings. I posted all the part numbers. These push on types are pretty much industry standards now in the big truck industry,
While your under there, do your dog one bushings.
I replaced my brakes on the tag axle too. Bought the whole thing. Back plate, brakes installed,with magnets. About 50 bucks per side.totally worth it. Why screw around with the rust etc etc. how you got to those top bolts on the bags I'll never know. I couldn't even get my hand in there. My bolts came out super easy, so I can't imagine the fun you had. They look pretty old. What I like,is everything you do to upgrade these old queens,makes it better and better...er.
I'm curious, you got air bags on your tag? Mine are torsion axles. The leveling valve is on my tag, but only bags on my drive axle. I have removed the leveling valves. With 80 pounds of air in the bags, she rides level, and less stuff to go wrong. It was a good idea, but I think overkill. As long as the tag is planted, and has the correct amount of weight on it, the use of an air adjustment valve is in my opinion, more of a gimmick, than a nessessity. With an air gage up by the dash, you can monitor your bag height. The only reason the compressed is cycling, is because the bags are constantly trying to hold the coaches ride height within an inch or two of it setting. On big trucks its critical because most of the time you got 2 axles back there, and ride height,pinion angle, driveshaft angle is critical for function. We don't have that issues. And if you really get it up in the air,the tag axle simply comes off the ground. No big deal.
I'm just going to have a switch to turn on my compressed. My bags take about a month to sag down a little maybe an inch. Well good luck with it. One more thing done for the next 30 years. DJ
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Old 07-16-2019, 08:19 PM   #4
4 Rivet Member
 
1986 34.5' Airstream 345
Londonderry , New Hampshire
Join Date: Mar 2017
Posts: 252
I got my second air bag out. The bottom was easy because of the
anti-seize compound. The top bolts were worse that on the first
air bag. One bolt snapped, no problem I am replacing them anyway.

My air bags are on the drive axle. I think that is the normal way
for the 345. My tag axle is the normal one for the 345.

There are two air control valves on the tag axle, one on
each side. However, the two air bags are connected together
so they always have the same pressure. I am not sure that I
understand the logic of the system.

I am considering replacing the whole tag axle with a new one.
They are $2,900 plus shipping. No drums; those are unobtanium.
My drums look OK but rusty. Clearly the electric brakes were
not working.

How do you know if you need to replace the tag axle? Mine
looks OK but how can I test it?
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Old 07-16-2019, 09:30 PM   #5
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1982 28' Airstream 280
Port Angeles , Washington
Join Date: Aug 2008
Posts: 1,916
The pinion angle and driveshaft angle do matter on our coaches, you have to keep u-joints and bearings happy.

I have never understood the 2 valve, interconnected set up. If the valves are not adjusted properly one could be letting air out while the other is putting air in.

The reason for leveling valves is to adjust for load changes. Eighty gallons of fuel and 50 gallons of water will make a difference. The valves have a delay of about 10 seconds built in so they are not reacting to every bump or pothole.

The way to check the tag axle is to weigh it. Airstream calls for a 3500 lb. tag. When I weighed mine it had 600 lbs. on the tag. This puts the drive axle in a near overload condition. When the rubber gets hard in the torsion axle the arms don't move and cannot carry the load as designed. If your drive axle bags ride high, you overload the duals and if the drive axle rides low you overload the tag. Remember if you loose a tag bearing and damage a hub, that is the one that is unobtainium.

I recently custom built an air ride tag axle for my 345, you can read about it here http://www.airforums.com/forums/f311...-183003-5.html starting at post #66. Probably more than you wanted to know but I did it and it seems to work well, I have about 2000 miles on it so far. Best of all the total cost other than my labor, came in less than the $2900 Airstream wants. All wear parts, bushings and air bags, are easily replaceable and I can fine tune the actual load on each axle.
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________________________________________


"Socialist governments traditionally do make a financial mess. They always run out of other people's money. It's quite a characteristic of them."
~ Margaret Thatcher ~
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Old 09-03-2019, 01:14 PM   #6
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1986 34.5' Airstream 345
Londonderry , New Hampshire
Join Date: Mar 2017
Posts: 252
I got my air bag system all back together. I replaced both air
leveler valves but I have a problem. The valves lift the AS
up so that the bags are at full pressure. The tag axle is lifted
off the ground. Both valves are exhausting air in an attempt
to lower the chassis. I don't know what is happening.

To diagnose the problem I have disconnected the linkage on
both valves. I set both valve levers in the middle position,
just at the point of releasing air but not releasing air.

In this position the bags still inflate to max pressure. I can
move the lever on one or the other valve or both so that they
release air but the bags remain inflated to the max.

It seems that the valves are adding air to the bags at the
same time that they are releasing it.

The new valves are Automann 171.H00450CA. They look
identical to the original valves. There are no air leaks
in the system.

What is going on?
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Old 09-03-2019, 06:34 PM   #7
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1982 28' Airstream 280
Port Angeles , Washington
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It sounds like you might have tank pressure going to the bags rather than through the valves. I would start by shutting off the air source. Drain the air tank so that no new pressurized air can enter the system. Now move the arm on one of your leveling valves to release air. The released air should be coming out of the small open tube. The bags should come down. Now disconnect the air lines from the valve and temporarily apply air to the lines, one should inflate the bags and the other should fill the tank. Do the same on the other side. You just have to retrace the lines to make sure the air is going where it is supposed to be going.
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"Socialist governments traditionally do make a financial mess. They always run out of other people's money. It's quite a characteristic of them."
~ Margaret Thatcher ~
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Old 09-03-2019, 07:03 PM   #8
4 Rivet Member
 
1986 34.5' Airstream 345
Londonderry , New Hampshire
Join Date: Mar 2017
Posts: 252
I will try what you have suggested. I have been banging my
head over this so long I might have missed the obvious.

The two lines to the valves were tie wrapped together making
it unlikely that they got reversed but perhaps they did.
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Old 09-06-2019, 05:09 AM   #9
4 Rivet Member
 
1986 34.5' Airstream 345
Londonderry , New Hampshire
Join Date: Mar 2017
Posts: 252
I went through my air suspension system again. I disconnected the
air lines from both valves that goes to the air bags. I pressurized
the air tank and manually operated both valves. I caused them to blow
air out the connection to the that goes to the air bag. In the
middle position the air stopped. If I put my finger over the the
connector that would go to the air bag I could build a little pressure
that I could then release moving the leaver to the release position.

There did not seem to be any leaks. The pressure in the tank was
110 PSI and I am running it from my shop compressor.

I connected everything back up to it's normal state. It seemed to
work OK. I adjusted the inflation level to where the air bags were
at 10 1/2 inches as specified in the owners manual.

The system started to lift slowly. I adjusted the level back to
10 1/2 inches. It held but one valve is slowly releasing air so
there is still something wrong. It seems that one valve must be
leaking air into the air bag.

This is much better than before where the system fully inflated
the air bags to full pressure and at the same time both valves
were blowing off the excess pressure at a high rate.

I think that one valve is bad. But which one?

My next test is to install a cutoff valve the can block the connection
between the right and left air bags. This should show me which of
the two (new) valves is bad.
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Old 09-06-2019, 11:53 AM   #10
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1982 28' Airstream 280
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Why don't you just block off the air lines to one of the valves? It will either operate normally or identify the bad valve. They are kind of redundant in the system and the possibility of them working against each other is high.

When I built the air ride tag in my coach I eliminated one of the valves. It seems to be quite happy running on a single valve.
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