Hi, I have had 2 identical 25 ft tri axle trailers (as sceen in pic). When being towed, at certain speeds they shake the towing vehicle, in a up and down motion. Looking for a cure, i have put 6 new tires on, and re bushed the suspension (it has leafs with slippers) and nothing changed. I have a 2 5/16 ball in the pintle to try to take up as much slack in the hole as possible. I sold one, and the fellow that bought it crushed the fenders, so he had new ones made out of 1/4 steel and apparently it has helped the shake. My good friend, who is a welder by trade and i have spent many hours looking at this problem. Were sorta thinking the problem is that where the axels are there is only the angle of the frame and no vertical piece between them like there is in front and behind the axles (causing it to wobble and shake over the 6 or so feet of where the axles sit) . SO.....Did the new fenders on the trailer i sold, made up of a thicker steel, strenghthen the frame between the wheels? (hope this makes sense) ...Has anybody had this problem or know of a cure? Many people have told me this is normal with a tri axle, but i dont believe a trailer was sold new that shakes like this. The yellow piece under the gray part in pic #2 is the vertical 3" piece welded to the 4x4 angle which is the frame. As you can see the 3" piece comes from almost the very front of the frame, stops right before the wheels begin, and continues on from the back of the rear tire to the back of the trailer. Thanks.
Homebuilt? Looks like the axles are not positioned correct. Not enough tongue weight. That one with that pallets, ouch! Did it stay bent like that after?
I would try changing your hitch hight. I've had the same experance towing with a trailer that was too low.
no they are not home made, I can't recall the manufacturers name. Both trailers look somewhat bent when they are loaded (they were probably over loaded at some point in there life) . My hitch height and trailer height are level when empty. I will try it at a higher setting.
Yair . . . cantfixathing . From what you describe the most flexible (weakest) point on what appears to be a pretty light built trailer is the section to which the axles mount. I would jig it up and square it and beef it up considerably in that area. Cheers.
Shakes when empty or loaded? Empty its just the stiff spring suspension and bias tires. Loaded you have frame flex issues. You are pushing that whole setup.
I don't know if this has anything to do with it, but I have found a world of difference in a proper pintle hitch on the truck vs. one of those combo ball things that allow the trailer to slam around, even though it is only an inch or so.
I'm certainly not a trailer expert but to me it seems like the trailer would be light on the tongue. Almost looks like it would be setup for a double axle and a third axle was added to the front. The middle axle should be about a 60/40 split on the trailer. On a 25ft trailer, about 15ft from the front.