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Old 01-30-2020, 07:29 PM   #1 (permalink)
fzl
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Trailer Tail end bobing up and down

Hi guys, I am needing some help on my trailer as far as what I need to do structure wise to fix the tail end from bobbing up and down while driving down the road. I built this out of a old 5th wheel camper from frame up. im wondering if there is any type of bracing to stiffen this thing up. maybe doing some bridging behind the axles underneath and ontop on deck?


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Old 01-30-2020, 07:34 PM   #2 (permalink)
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Old 01-30-2020, 07:40 PM   #3 (permalink)
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Thank you Black!
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Old 01-30-2020, 07:45 PM   #4 (permalink)
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You need some vertical shear strength or preload some tension on the rear 2/3 of the trailer length.
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Old 01-30-2020, 07:47 PM   #5 (permalink)
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You need some vertical shear strength or preload some tension on the rear 2/3 of the trailer length.
can you explain a little more this is my first build
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Old 01-30-2020, 07:50 PM   #6 (permalink)
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[IMG][/IMG]

this wouldn't help at the rear?

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Old 01-30-2020, 08:00 PM   #7 (permalink)
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the frame rails are too damned small.

you need to truss the whole thing.
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Old 01-30-2020, 08:06 PM   #8 (permalink)
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it is 2x6 rectangle tubing from front to rear, I have extended trailer behind axles using 2x6 rectangle tubing also. with fish plating and welding 1x2 3/16 angle iron underneath 1 ft back.

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Old 01-30-2020, 08:21 PM   #9 (permalink)
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it is 2x6 rectangle tubing from front to rear, I have extended trailer behind axles using 2x6 rectangle tubing also. with fish plating and welding 1x2 3/16 angle iron underneath 1 ft back.
There ya go, you have too much rear overhang. Doesnt look like you utilize the extra space with the SxS
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Old 01-30-2020, 08:27 PM   #10 (permalink)
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[IMG][/IMG]

this wouldn't help at the rear?
Sure would.


What thickness 2x6 tube?



Theres a few ways to handle it.
Your pic sould work just fine

You can add some 1/8" ribs bent into u shape and added to the bottom of your 2x6. The deeper the better.

Similar to your ladder truss design. Use a tension rodwithe the forward end attatched under the shed, over keel point and back to the tail of the trailer. This willl pulle down on the tail of the trailer so i would start by placing it on jack stands right behind the rear axle and backing the sammy to the tail to get the extra flex drwn out first then tension the rods. Probably far and away from the BEST solution but it will probably be the cheapest.
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Old 01-30-2020, 08:40 PM   #11 (permalink)
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There ya go, you have too much rear overhang. Doesnt look like you utilize the extra space with the SxS
me and my wife plan on buying our son a fourwheeler this Christmas, that is the reasoning behind the extra space. he is getting to big to be riding with us.
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Old 01-30-2020, 08:55 PM   #12 (permalink)
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Sure would.


What thickness 2x6 tube?



Theres a few ways to handle it.
Your pic sould work just fine

You can add some 1/8" ribs bent into u shape and added to the bottom of your 2x6. The deeper the better.

Similar to your ladder truss design. Use a tension rodwithe the forward end attatched under the shed, over keel point and back to the tail of the trailer. This willl pulle down on the tail of the trailer so i would start by placing it on jack stands right behind the rear axle and backing the sammy to the tail to get the extra flex drwn out first then tension the rods. Probably far and away from the BEST solution but it will probably be the cheapest.

i am planning on going to pick up some material tomorrow for it. im looking at getting some 1/4 x 1/2 flat steel & some 1 1/2 x 11gauge square tubing. is that overkill?

so your saying load SidexSide all the way to the rear and run my ladder bracing on bottom side of frame with tension on it from the SidexSide? i can only go up to the rear axles because of the hangers on the frame. how much depth should my ladder have off of of frame?
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Old 01-30-2020, 09:15 PM   #13 (permalink)
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3 or 4" is prob fine.

But if you dont reach past the rear hangers you just going to snap the ass half off at the hangers. It need to lap to front half of the trailer.

The rig on the rear would be for a tension rod setup.

Since your set on the ladder id put the jack stands at the rear and let it dip a few inches in the middle.
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Old 01-30-2020, 09:42 PM   #14 (permalink)
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3 or 4" is prob fine.

But if you dont reach past the rear hangers you just going to snap the ass half off at the hangers. It need to lap to front half of the trailer.

The rig on the rear would be for a tension rod setup.

Since your set on the ladder id put the jack stands at the rear and let it dip a few inches in the middle.

I guess im not understanding the tension rod your talking about. Im sorry not really set on anything just trying to understand about the tension rod.
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Old 01-30-2020, 10:59 PM   #15 (permalink)
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Just think of it as a giant all thread running the length of the trailer.

Much like your angular ladder bar concept but opposite psi use.

Your ladder structures are designed to support and strengthen under compression.
Tensioning the trailer pulls it togther harder stiffens the frame. The trailer will be trying to pull the rod apart.

If you ever see a large swinging gate they run criss cross. They help support the free edge of the panel and square the gate . Its impressive how much they will stiffen/rigidify a gate
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Old 01-31-2020, 04:09 AM   #16 (permalink)
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How much work was cutting down the 5th? I'm planning on eventually picking one up to make a cheap trailer.
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Old 01-31-2020, 05:03 AM   #17 (permalink)
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Just think of it as a giant all thread running the length of the trailer.

Much like your angular ladder bar concept but opposite psi use.

Your ladder structures are designed to support and strengthen under compression.
Tensioning the trailer pulls it togther harder stiffens the frame. The trailer will be trying to pull the rod apart.

If you ever see a large swinging gate they run criss cross. They help support the free edge of the panel and square the gate . Its impressive how much they will stiffen/rigidify a gate
So run it like the angular rod bracing on picture thru the axle hangers? If so what size rod would be sufficient? Also how should I cut the stems?
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Old 01-31-2020, 05:04 AM   #18 (permalink)
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How much work was cutting down the 5th? I'm planning on eventually picking one up to make a cheap trailer.
I received it with just a frame and started my build from frame up. It’s taken 11 months to get it this far. But I only been working on it on free time and weekends.
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Old 01-31-2020, 05:06 AM   #19 (permalink)
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I guess what u didnt (or maybe did) understand is that the box on the original trailer was designed to give it the stiffness it needed.

My 28' open deck 14k goose has 10" I-beams running underneath supporting a deck thats a little lighter then your entire trailer. Maybe im being dramatic but that thing looks like a disaster waiting to happen. Everything on that trailer looks way too light to hold the weight and the wheels r too far foward.

It needs I-beams or several trusses welded in.
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Old 01-31-2020, 05:44 AM   #20 (permalink)
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I guess im not understanding the tension rod your talking about. Im sorry not really set on anything just trying to understand about the tension rod.
you're effectively increasing the height of you stressed member with a truss.

the further the top of your truss is from the frame rail the stronger it will be.
You're basically building a bridge.

it definitely needs to extend all the way to the front, or you're just going to fatigue wherever it stops and it will eventually crack.
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Old 01-31-2020, 05:47 AM   #21 (permalink)
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I guess what u didnt (or maybe did) understand is that the box on the original trailer was designed to give it the stiffness it needed.

My 28' open deck 14k goose has 10" I-beams running underneath supporting a deck thats a little lighter then your entire trailer. Maybe im being dramatic but that thing looks like a disaster waiting to happen. Everything on that trailer looks way too light to hold the weight and the wheels r too far foward.

It needs I-beams or several trusses welded in.
Yes I knew that trailer frames rely strictly on the structure above the frame. Same way a enclosed trailer works. The camper part seems fine when driving down the road, it’s just after loading the SxS going down the road I can see the rear going up and down going down the road.
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Old 01-31-2020, 06:31 AM   #22 (permalink)
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I guess im not understanding the tension rod your talking about. Im sorry not really set on anything just trying to understand about the tension rod.
you're effectively increasing the height of you stressed member with a truss.


the further the top of your truss is from the frame rail the stronger it will be.
You're basically building a bridge.

it definitely needs to extend all the way to the front, or you're just going to fatigue wherever it stops and it will eventually crack.
What material should I use to make this truss to be able to get it in between the axle hangers?
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Old 01-31-2020, 06:40 AM   #23 (permalink)
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run truss to spring hangers
transistion truss to the top
run over axles
transition truss back to the bottom.

that's what I would do.
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Old 01-31-2020, 07:00 AM   #24 (permalink)
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run truss to spring hangers
transistion truss to the top
run over axles
transition truss back to the bottom.

that's what I would do.
Pretty much make it look like this then.

https://pjtrailers.com/options/under...llery1274%5D/0
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Old 01-31-2020, 07:22 AM   #25 (permalink)
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yes.

you're increasing the vertical shear of your existing frame rail.
when the frame rail wants to flex it has to act against that piece of flat steel and either compress it or stretch it.

Personally I'd do it with round bar stock.

and don't PM me for tech help. the point of the forum is to share things openly. discussing solutions via PM helps nobody in the future when they search for the topic.

I understand that the search is now useless, so I won't go full sirch n00b, but copy and paste this directly into google and start reading.
What you're doing has been done a bunch of times.

Code:
trailer truss site:www.pirate4x4.com
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