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Equipment trailer flexing

Discussion in 'Trailers' started by HogValleyFarm, Mar 27, 2020.

  1. HogValleyFarm

    HogValleyFarm Member

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    I recently bought a 5 ton equipment trailer that has a slight twist it in. I have not yet had it in the shop on the concrete yet, but you can still see on the back left side there is a slide downward slant towards the back. My plan was to weld to 1x1 square tubing onto the bottom on the rails that the deck boards are sitting on in an X format to try and give the trailer some more support and strength. Does anyone think I should use something different on the bottom maybe some C channel, or would you support it a different way? Also the boards are a little beat up on the top but they are not rotten at all. My plan was to just flip the boards over and get a few more years out of them? Anyone done this with their deck boards before? I have crawled all underneath the trailer and I do not see any cracks or bends in any of the trailer cross members. T1_IMG-1228.JPG T2_IMG-1229.JPG T3_IMG-1230.JPG T4_IMG-1231.JPG
     
  2. Delmer

    Delmer Senior Member

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    Why? does it bother you that much?

    If you don't see anything in the tires, springs, or frame that's causing it, then it's probably tweaked a little bit. pretty good for what it is.
     
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  3. HogValleyFarm

    HogValleyFarm Member

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    i guess I am just looking to fix the problem right and just be done with it, I just don't want it to get worse over time.

    That was the same thing I was thinking, maybe someone overloaded it at one time and slightly tweaked it...
     
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  4. DMiller

    DMiller Senior Member

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    Every Trailer flexes, HAS to or they crack and bust to hell. Stiff is not necessarily all that great where we in the 1970s trucking industry saw 'Technologic Marvel' stiffened frames do just that, now Dodge trucks have a severely stiff frame and I suspect the cracking will start up within three years of the first productions.
     
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  5. Truck Shop

    Truck Shop Senior Member

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    Load it heavier on the other side, after time it will match.
     
  6. Ct Farmer

    Ct Farmer Well-Known Member

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    The tail is bent down because it was loaded heavy with no support under it. Could also have been run heavily tail loaded and beat it down while moving. Many trailers look this way. Crib the tail when loading.

    Rather then adding any steel, clean and paint the bottom to keep it from rotting out. If in the cleaning process you find cracks then make proper repairs and add support to the cracked area. I would avoid box steel, water gets inside and stays there and rusts it from the inside out. Add drains or leave open ends. Better yet use channel or I beam.
     
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  7. Nige

    Nige Senior Member

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    Maybe it was a 5-ton trailer that at some point in time had significantly more than 5 tons loaded over the back end without adequate support as was mentioned before..?

    Trying to make something more rigid is not necessrily the best long-term solution IMHO. It might be better to just make sure both rear corners are adequately blocked when you load/unload it in the future.
     
  8. Ronsii

    Ronsii Senior Member

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    Once you start 're-engineering' the design you will most likely have issues down the road with things cracking... like others have said: they are designed to flex... once you change where that happens all bets on the design are off.
     
  9. HogValleyFarm

    HogValleyFarm Member

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    I appreciate what the input from everyone. Instead of trying to weld any support on it what does everyone thin about trying to bend it back straight? I agree I think at one point in time the trailer was probably most likely over loaded and abused more than once sadly...
     
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  10. DMiller

    DMiller Senior Member

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    I would leave it be
    Adding stress into already stressed metal actually increases chance failure.
     
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  11. Nige

    Nige Senior Member

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    Ah, the good old engineer's term "bend it straight" - a great oxymoron if I ever heard one. The problem is that every time the structure is bent it takes some of the strength out of the material. Bend it back and forth enough times and it will eventually fracture. I'd just leave it as it is and try to ignore it.
     
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  12. Welder Dave

    Welder Dave Senior Member

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    Put supports on the loading ramps or block the back of the trailer when loading it. If it really concerns you a place with a frame machine may be able to straighten it. It looks like a channel frame. When you replace the deck you could take flat bar and box in the channel on the back of the trailer. If the channel is say 6", get some 3/16 or 1/4" steel sheared 5 1/2" wide and you can do a nice fillet weld top and bottom on the channel. You could use a zip disc to cut down 6" flat bar but a cutting torch might warp it badly if not done right. It will add a lot of strength even if you had to use a little heat to get it straight. That's what they do to strengthen the frames when they make hot rods out of old cars. Drill a few small holes to drain any water that gets inside the boxed in channel.
     
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  13. repowerguy

    repowerguy Senior Member

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    Block the side that’s bent down and not the high side, load it a time or two, it’ll straighten out...
     
  14. HogValleyFarm

    HogValleyFarm Member

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    An update as to where I am at...With everything going on work has been crazy so I have not had time to work on my new trailer as much as I would like to. I finally got all the deck boards off and decided I am going to replace them all with pressure treated southern yellow pine. I am also going to cutoff the old fenders and replace them, here some more pictures that will hopefully show the twisting a little better. T1 IMG-1280.JPG T2 IMG-1281.JPG T3 IMG-1293.JPG T5 IMG-1295.JPG
     
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  15. Welder Dave

    Welder Dave Senior Member

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    Looks like the whole trailer has a little twist in it but a channel frame will do that. You could try blocking the low side and driving something heavy on it or put something heavy on and jack up on the low side a little higher than it needs to be and leave it overnight. It might straighten a little. That's a job where having an anchor in the floor would help.
     
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  16. Canadian_digger

    Canadian_digger Senior Member

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    I think I have heard you should not use pressure treated lumber on a trailer. I forget the exact reason. Could be that is corrosive and will rust the frame faster. Maybe someone can confirm this?
     
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  17. Tenwheeler

    Tenwheeler Senior Member

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    If you use it need tar paper or something between the steel and wood.
    The chemicals in the word eat up the steel.
    Never saw that on a trailer but metal building siding. Just sharing the idea.
     
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  18. Ronsii

    Ronsii Senior Member

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    The regular pressure treated lumber like they sell in lumber yards and home depots will eat and regular steel it comes in contact with!!! this includes screws/bolts going through the wood to fasten it to the trailer... you will need stainless or heavy galv fasteners. I have seen fences with 16d nails into 4x4 press treadted posts only a year old and there is nothing left of the nail:eek:

    Normally they don't put treated wood on a trailer because it splinters /falls apart...etc... and just doesn't hold up to loading/unloading cycles... however I don't know about treated southern yellow pine??? if they use a different (green) preservative on it or not...
     
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  19. Delmer

    Delmer Senior Member

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    The "interim" green treat chemical was extremely corrosive, the current one is not quite so bad, maybe not any worse than the salt in NY. Still, I'd prefer untreated hardwood over treated SYP. SYP will crack and splinter, hardwoods are mostly tougher, even if they're not stronger than SYP.
     
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  20. HogValleyFarm

    HogValleyFarm Member

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    The pressure treated boards that I took off did pretty much eat the carriage bolts... That being said the portions of the frame where the deck boards were resting on do not look any more rusted than the rest of the trailer. The salt up here in NY is pretty harsh stuff! I was thinking the pressure treated SYP after looking at the PJ trailers site. All of there trailers come standard with the treated SYP. What would be my next best option for decking boards? I have also thought about just doing the whole deck in diamond plate but I wasn't looking to spend all that much on the decking.

    From PJ website:
    Our pressure treated No 2. Southern Yellow Pine is our standard lumber. This wood is native to the Southern United States and has great loading bearing capacity. It is one of the hardest pines and provides very good durability for trailer decking.
     
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