I don't disagree that too heavy of a WDH bar may contribute to some Airstream failures. My point, it that too heavy of a WDH bar "SHOULDN'T" harm a trailer frame. Most of the failures that I have seen pictures of, have nothing to do with the WDH bars. Many of the failures are in the back.
Buyers are not told that "Early frame failures are usually due to grossly out of balance running gear, or, towing with a super heavy duty tow vehicle and an excessively rated hitch bars, or a combination of those".
If you have a failure, how do you prove a negative? How do you prove that your running gear was balanced, that you didn't use a heavy duty truck and you didn't have excessively rated hitch bars? Besides, the frame will probably last past the warranty and the buyer is stuck with the problem, in most cases.
As far as rubber torsion axles go, you can't replace the rubber, you replace the entire axle. I plan on my trailers lasting a lot longer than 20-25 years. So far my 69 Avion camper is like new and my 1988 trailer is like new. I expect them to last the rest of my life. Maybe my expectations are too high. It is much cheaper, after 20 years or so, to just buy new hubs, and backing plate assemblies with the brakes and install them with new bearings and have a like new axle.
Now, as far as trailers go, if I needed a travel trailer, I would really like to find a fairly new Airstream with a cracked or damaged frame. I would remove the shell, make a new frame and have a great trailer. The frame would take me about a week to make, but I wouldn't call it a semi-monocoque system. I would guarantee that it would last the life of the trailer and beyond. It would weigh about 300# more than the factory trailer and have a higher GVW. The hardest part is removing the shell, and reinstalling it.
