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Old 01-07-2013, 06:51 PM   #309
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MOR/Ryde old style suspension.

http://tincantourists.com/wiki/lib/e...suspension.pdf
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Old 01-08-2013, 09:35 AM   #310
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Also, how did Avion attach their body to the strong frame without tearing it apart? It seems that everytime I bring up putting a stronger frame under an Airstream, the issue brought up by experts is that the shell will be destroyed. How did Avion do it? The shell seems to be very similar.
A rigid frame will help preserve the shell. A house is no better than its foundation.
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Old 01-08-2013, 11:59 AM   #311
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A rigid frame will help preserve the shell. A house is no better than its foundation.
A house does not move,or hit bumps, except from an earthquake.

An Airstream is exposed to every type of bump, pounding, and highway punishment you can think of.

Contrary to a "rigid" frame, a light frame is all that Airstream needs, because the strength is in the shell.

To add a "beefed up" frame to an Airstream shell, is going backwards.

That extra weight from that beefed up frame, must be supported by the shell. Therefore many more points of attachemnt must be used and with greater strength fasteners.

Regardless of the rigid frame, it will still flex when it hits bumps, regardless of the type axle suspension.

Andy
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Old 01-08-2013, 02:51 PM   #312
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Andy is right, all frames will flex. A heavier frame will not flex as easily. I'm certainly no expert on Airstream trailers, but I am a reasonably knowledgable person when it comes to trailer frames. It appears to me that the Airstream design starting in the 1930s was developed to build a high quality trailer with minimal weight to work with the vehicles of the day. There is no doubt that the Airstream is the lightest. It also appears that they didn't modify their design to keep up with the modern vehicles. Two or three hundred pounds would have made a world of difference to the tow vehicles in the 1930s and 40s. But it todays world, that weight difference wouldn't make any difference to a modern 3/4 or 1 ton truck, especially when you consider all the weight added with options that are available today. An increase in 300-400# for a frame and axle upgrade could probably get you 1000-1500# of extra gross vehicle weight with no reasonable chance of your frame ever breaking. It appears that Silver Streak and Avion went to the heavy frame concept and Airstream didn't. My estimate of the cost difference on a very expensive trailer is about $300-$400 per unit. To me, a heavier frame and axles should at least be an option for Airstream buyers. The other option should be the Avion style insulated floor. If the plywood on those floors were epoxy coated before they were laminated, that would be an awesome floor, which in turn would make an awesome trailer. It doesn't cost much to do it when you are building the trailer, but it sure is expensive later.
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Old 01-08-2013, 03:13 PM   #313
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Airplane structures have to have a frame and it needs to be strong enough to withstand the loads being put on it by the shell. Airplanes have frames and stucture inside that pretty shell. Airstreams have gotten heavier and the frame and the attachment points to the frame are not strong enough. Also tow speeds are higher and tow vehicles have gotten more rigid as Andy has said. The shell can only do so much. It works together with the frame. I have studied aircraft structures and what I am seeing are frame issues not fatique issues. The shell would crack and rivets would fail if that were the case.

Perry
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Old 01-08-2013, 04:08 PM   #314
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Airplane structures have to have a frame and it needs to be strong enough to withstand the loads being put on it by the shell. Airplanes have frames and stucture inside that pretty shell. Airstreams have gotten heavier and the frame and the attachment points to the frame are not strong enough. Also tow speeds are higher and tow vehicles have gotten more rigid as Andy has said. The shell can only do so much. It works together with the frame. I have studied aircraft structures and what I am seeing are frame issues not fatique issues. The shell would crack and rivets would fail if that were the case.

Perry
I believe that you are correct. Avion figured it out in the 1950s. With more and more options being added, the problem only gets worse. The curious thing is why the 22' models are worse than the others. It has to be the load and stress causing the frame to fatigue faster. When a frame is designed to be that light, and where a couple of minor factors cause significant frame damage, the frame is obviously too weak. If Airstream would just use the appropriate size structural channel instead of "C" channel for the main members, and heavier guage cross members and outriggers, they would be fine. A higher rated set of axles would round it out real nice.
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Old 01-08-2013, 06:24 PM   #315
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Part of it is the way the frame is designed. With the current design, there is no direct structural support of the shell accept at the front and back. The sides are supported by cantilevered outriggers and not directly by the frame. The frame flexes especially when the two main attach points, two 5/16" inch screws, either rot or pull through unsupported sheet metal (C-channel) at the bottom of the skin. Now the outriggers are supporting all the load and they bend which makes the frame sag even more. Yes Andy, an already borderline design is pushed over the edge by stiff load bars and out of balance running gear but I don't think you can blame failures on that alone. To fix the problem, you will need a very strong frame like the truss structure fix a few posts ago or very good attachment of the shell to the frame by making outriggers go from one side of the trailer to the other including between the frame members so the frame won't twist. Also adding twice the number of outriggers would be a good idea. This would allow that super strong shell to actually support the frame.

The 22 footer main frame problem is they used channel that is not tall enough which greatly reduces the stiffness on an already weak design. Now those screws and weak sheet metal attach points are stressed to the MAX. The outriggers are even less effective for the same reasons. They are now much less strong because of the height problem. The technical term is moment of inertia. The same amount of metal gets much stronger the larger the distance between it and the centroid of the material. A pipe is an easy example. The bigger around it gets the stronger it is.

Perry
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Old 01-08-2013, 07:12 PM   #316
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Another issue that I see with the frames, is the amount of rust on them in just a few years. A structural channel may withstand some rusting, but the thin "C" channels aren't very strong to start with and by the time they get significant rust, there can't be much strength left.
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Old 01-08-2013, 08:14 PM   #317
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To get back onto the topic of 22 ft trailers failing the frame and the often heard argument on Airstreams that have a stiffer frame WILL cause problems, I gotta say....hummm. No way.

I'm very familiar with the concept of allowing a structure, in its totality, to flex as a design. The well proven concept in general does not have a side bar that supports the notion of reducing the flex of element 'A' will cause parallel element 'B' to fail.

Its well known that tall buildings and bridges flex so they will not snap. If designed to not flex, they would contain so much structure that they would no longer be functional. Stiffening the frame of a bridge does not cause the road bed to fail, the frame fails from cyclic loads. Likewise with our beloved trailers, reducing the flex of the frame will only cause the shell to be less of a structural component. Imagine a solid granite slab with an airstream shell mounted to the top of it. Place the entire mess on the back of an 18 wheeler and insert it into a Hollywood get-away scene. Until the Action Hero manages to break the slab, the shell is quite safe and secure. If fact, it's very well supported and will not see much flex!

IMHO, the frame failure indicates a system that is allowed to flex too much.

Your mileage may vary, limited time offer, if you order in the next :10 you can also receive a free second sham wow...
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Old 01-08-2013, 09:04 PM   #318
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Based on over 46 years experience repairing Airstreams and writing the crash book some 43 years ago, I hate to tell you, but facts are facts.

Your frame broke where it did because of vibration, simply caused by lack of proper running gear balance. A secondary effect could be a bad axle, excessive hitch bar rating and/or excessive rated tow vehicle, or a combination of these things.

That has happened hundreds of times, and will continue unless balancing is properly used.

A broken frame, is not the result of design, but is the result of improper use.

That has also proven itself over the course of many years and many failures.

Andy
So Andy are you saying that If I had a trailer that had a 310lb toung weight,(total weight of trailer 3600 lbs) using 600lb WD hitch and being pulled by a 1 ton dually that the frame could become damaged?
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Old 01-09-2013, 08:45 AM   #319
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Sad , but true , Had the Avion, Silver Streak and Spartan brands survived till now , they too would have probably gone down the toilet the way Airstream has .
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Old 01-09-2013, 11:55 AM   #320
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Sad , but true , Had the Avion, Silver Streak and Spartan brands survived till now , they too would have probably gone down the toilet the way Airstream has .

?????what is sad but true????

Bean counters insisting engineers use less material....build in obsolescence

I had a 60's something Silver Streak over 30'(I forget now)....over packed it to the gills and moved my family 600 miles......pulled it with an old 1976 Dodge crew cab 3x4 1 ton....if I knew then what I know now....she survived some how.....today I'm worried about packing a dutch oven
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Old 01-09-2013, 03:00 PM   #321
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Sad , but true , Had the Avion, Silver Streak and Spartan brands survived till now , they too would have probably gone down the toilet the way Airstream has .
Airstream never had the frames those other trailers had. Airstream had a great reputation that they have been living on for years. Their frames never were strong. I think that AS had a different engineering goal, which was to be as light as possible. That became somewhat irrelevant when the options added to trailers made them fairly heavy. The frames never evolved with the times.
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Old 01-09-2013, 03:57 PM   #322
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Airstream never had the frames those other trailers had. Airstream had a great reputation that they have been living on for years. Their frames never were strong. I think that AS had a different engineering goal, which was to be as light as possible. That became somewhat irrelevant when the options added to trailers made them fairly heavy. The frames never evolved with the times.
When I compare the frame on my 05 to the frame on my 66 , it doesn't
take a rocket scientist to see that the older frame is vastly superior to the
modern one.
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