"Eric Greenwell" wrote
It seems remarkable and counter-intuitive that even 1/8" (a lot more
than my hitches) of total slop at one end of a 30 foot long trailer could
have any influence at all. Since the tires are approximately in the
middle, that'd be only an 1/8" at the tail. My trailer is stable, yet I
can still see the tail wagging 1 to 3 inches at times as I'm driving, far
more than a loose hitch would cause.

Probably true. I stated that a bit strongly, perhaps. The loose hitch
probably does not do much to cause a sway.

If a trailer was verging on unstable, it could be conceiveable that it would
only take a small factor to start exciting the system, and then the trailer
allows the oscillations to amplify and build on their own.

Sway is like a harmonic vibration. If it starts to vibrate, or sway, it can
self excite and built on the small wiggle that got it started.

Still, I guess what I was meaning to ask was if people had a sloppy fit that
rattled back and forth that they had to deal with. I can not stand to hear
something like a loose hitch rattle as I head on down the road. Something
had to be done, and the welds are what I came up with. I tried the metal
shims (like the nails that someone mentioned) and they eventually fell out.
I put my gray matter to the problem and the welds building the fit tighter
is what I ended up going with.
--
Jim in NC

Perhaps there were some other changes made at the same time, like changing
tire pressures, moving stuff around in the trailer?

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz