semi OT: wagging trailer

 As I was following my buddy to a catering gig Saturday I watched in
horror as his trailer wagged back and forth jerking the tow vehicle
with each change of direction.

I wondered about alignment, load placement, axle placement (it's
welded, so not easily adjustable), tongue length, and any other
geometry or physics theory I could apply to suss out the problem.

I am certain there's some knowledge here on this subject. Anybody care
to offer tips?

TIA,
Dean
using the service entrance

 easy. tires with too low pressure. makes trailer bounce on them from
side to side, the bounce translate to entire trailer and that makes it
swift from side to side like you describe and let me guess: your
friend was driving at least at 80kmh or more?

-- t

 Tiago Rocha wrote:

I would suspect overloading, or at least improper loading. A tandem axle
trailer will carry more weight but is more sensitive to improper
loading. The fore and aft axles need to be balanced to carry similar
loads. The tow vehicle should hold the trailer tongue at the proper
height to distribute the loads on the axles.

Is popular among some to use car tires on trailers. I'd check the
friend's trailer for car tires.

Check the tow vehicle, is it rated to pull the trailer's load? Are the
tow vehicle tires inflated properly? The tail can wag the dog and if the
dog doesn't dampen the wag then it just bounces back and forth getting
worse and worse. Oscillation.

 
That is not my experience at all. I've got a 7x14 enclosed trailer and
you can load it just about any way you want from full to empty and it
tracks straigt as an arrow. I've had other 2 and 3 axle trailers...
same thing. A single axle is very sensitive to tongue weight and can
go absolutely nuts if the tougue is too light. Other things like bent
axles, bent wheels, aire pressures, etc can cause problems as well...

 In article
 dfhyman@optonline.net wrote:


All of those have some component in the fishtailing experience, but
the most common problem is simply load placement--if the trailer is
loaded more heavily in the back it will often cause fishtailing.
General rule of thumb is 60% of weight should be forward of the axles,
40% rearward. some trailer/hitch combos may not be designed that way
though...

here's a primer:
http://www.sherline.com/lmbook.htm

--
Charles
'99 YZ250