Short trailer tongue>

[tanglediver]

I wonder if those with design experience in building trailers can comment on a situation that an aquaintance of mine has been experiencing. The trailer in question was built from a short, utility bed that had been a minisized truck. It has still got a light truck axle under it, as well as underinflated non-trailer tires, plus there is a small overhead rack above the bed. First, I commented that he needs to fill his tires.
The real question is concerning a handling issue that he has with it doing anything above 40mph. I was about to guess it was fishtailing, when he said, "No, it rocks left and right very much." It compresses the left and right side suspension in an alternating manner. The most notible abberation from the norm to my eye was the very short tongue configuration. So much so, that I doubt he could turn full lock with out binding the tongue (which had a bracket built to hold a square gear box) and tow vehicle bumber.
Would a short tongue cause a trailer to rock left and right?

[bensweld]

Sounds like trailer tongue is deffinately too short.If trailer axle is too far forward on trailer it will also do the swayying.(not enough weight on tongue).Tires also need proper air pressure.

[tanglediver]

I found the post I was looking for in a search...
http://weldingweb.com/showthread.php?t=19510&highlight=trailer+tongue+design

[Sandy]

I doubt that it's lined up right. That is the coupler isn't centered. It's cutting so hard the spring on one side only compresses, which changes the axle orientation and causes it to rock harshly and cut back the other direction.

[tanglediver]

I only glanced at the rig briefly over the weekend and did not try to measure anything as with a tram. If I can get a picture next time I will try to share that. I know the tongue is going to be rebuilt. I was only asked for an opinion and am not doing any work...that I know of! :blush2:
Thanks!

[triptester]

The main causes of fishtailing are axel alignment, a weak spring, and tires. Tires can be under inflated, weak sidewalls, or mismatched sizes. A short tounge does not cause fishtailing but it makes other problems more apparent.

[Dualie]

I would start by airing the tires up to max inflation pressure. then take it for test drive.


IF problem persists then I would check the axle alignment from the ball hitch centerline to the center of the spring perches. Road test again.


If the problem still persists then I would look at installing shock absorbers, the springs might be oscillating back and forth and just intensifying as your going down highway.

[MoonRise]

Soft under-inflated tires, misalignment of tongue to axle, improper tongue weight, bad/soft shocks, out of balance wheel/tire on the trailer, etc.

A short tongue wouldn't -cause- the trailer wheels/suspension to hop left-right.

[tanglediver]

I was not very clear, it actually rolls left and right, not fishtailing. I may see the guy at next saturdays welding class again and I'll ask him. Probably just tires! :laugh:
Thanks all! :)

[txtowman]

it's top heavy. I have seen a hunnerd of them like that it needs a really serious sway bar. the pickup bed trailers are notorius for that.

[DesertRider33]

My old '69 Chevy 1/2-ton longbed pickup bed trailer rocked side to side alot too. It had leaf springs with no shocks and a rather heavy camper shell that was taller than a pickup cab roof. Bumps in the road and side winds would get it rocking pretty good. I took the camper shell off and replaced the tires and kept them aired up to max pressure and the rocking wasn't too bad. The tongue was rather short, but I don't think that had anything to do with it rocking. I had to use an extra long hitch on the truck to keep the little trailer from contacting the rear jacks of my slide-on truck camper, since the trailer tongue was short and the camper was wide and I couldn't see the trailer in the truck mirrors untill it was already turning. That was a very hard combination to back up without jack knifing. My 20' flatbed is much easier to back up.

[flatbustedbroke]

A set of heavy duty shocks and possibly overload springs depending on how heavy he loads this trailer.

[triptester]

The problem that comes from using a pickup body with original suspension is that the springs are long to provide a smoother ride. They are not intended to be used on a trailer. A sway bar may help.

Normal trailer springs are always short and stiffer than car or pickup springs.