Front axle of tandem trailer shifting

myredracer wrote:

BubbaChris wrote:
I vote for normal. I did a lot of internet searches after it happened to me the first time earlier this year (also new to TT).

What set my mind at ease were the comments that you can see the same effect on commercial trucks and trailers if you watch for it.

Luckily it sounds like what happened to myredracer is not a common problem.

I guess unless you have had one of these frames as well as had it inspected by a gov't certified frame shop, you just won't know. It's more common than you think with these particular frames and a lot of owners don't know until something happens.

You make some good points. I don't know what kind of axles (leaf spring or rubber torsion) the OP has or what type of frame he has. I have built equipment trailers on and off for almost 40 years, and the leaf springs will flex in a turn, but not as much as your pictures show. I don't know what kind of a frame the OP has, but excessive flexing of the frame is not good. If the frame is flexing too much it will eventually fatigue. Many TT manufacturers are too cheap when it comes to the frames and axles, and they have been getting by with it for years. Your idea of a video camera under the trailer is a great idea to see if the frame is flexing too much, especially if the TT has the manufactured sheet metal frame.
When building equipment trailers I have used structural channels, rectangular tubing or "I" beams. I prefer the structural channel the most because of it's properties of strength with the thick flanges. They are basically half on an "I" beam with a thick web. They are also nice because they don't warp as much as the tubing when you weld them and you don't have to worry about rust on the inside.
The rectangular tubing frames will resist twisting more, and some folks think that is what you need for strength. The fact is that the frames are supposed to twist. You will notice that semi truck frames use a "C" channel of high tensile steel, but they aren't structural channels.
I have never used the "manufactured" sheet metal frames for the trailers that I have built. I imagine the TT manufacturers use them because they are lighter and cheaper. The problem is that if you are going to have some extra weight, it is best to have it in the frame. My estimate is that a TT with a quality frame and axles will probably only weigh about 200# more than a weak one, depending on the size of the trailer of course.