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Material for new car hauler?

TRINDU

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I'm going to build my next bumper pull and I'm torn between 5" 9lb channel or 5x3 x .1875 tube for frame and tongue. Thought about i-beam, but already have a heavy hauler and want to stay reasonably light.

Current idea is 20ft x 83", wrapped tongue, 4ft steel dove, 6k axles. I've quoted multiple brands and their all over $4k+, fuck that.

People keep trying to persuade me to channel because "the tube will rot inside out". Yet I have 70s scout frame and 80s Toyotas that dont have a spec of rust. I figured square tube would be easiest to work with and stay rigid. Instead of having to notch ever mount or crossmember with channel

Engineer friend told me to look at point burden stress tables, but that's little bit above my redneck paygrade.
 

BJS

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tube can be managed it really depends on where you live and what the climate is there. If you're out west where things will dry out you won't have a problem with tube. Maybe drill a few drain holes strategically like are in the frames of the trucks you mention. If you're in wet country or salty lands then tube is going to suck. That being said there are tons of tube trailers sold around here for boats.
 

Tiha

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I built a 16ft on 2x6 tube. Waayyyy overbuilt. Wish I had used 2x4 but I also agree tube is better than channel.
 

TRINDU

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I'm not concerned about rust, at all, for any reason. But some reason other people think it will? I do s lot of painted tube boat trailers.

I dont mind overbuilt, by current light duty 18ft is 5x3 angle. Its served its purpose, but i want a solid BP. Something I could do 7-8k and not worry.

Concerning weight, theres not too big of a difference:

5x3x5/16 angle: 8.2lb/ft

5x3x3/16 tube: 9.4lb/ft

5x1.885 channel : 9.0 lb/ft

5" I beam: 10 lb/ft
 

YotaAtieToo

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Have you checked prices? I think the channel would be cheaper but I could be wrong.

Tubing is fine outside the rust belt. My old work had a 40 year old tune frame trailer that was still going.

5x3 is an odd size, why not just 2x5 or 2x6?

You won't have to notch the crossmembers if using a wood deck since they be ~1 1/2" down from the top.

Also why a dove? I have dove tails, unless they're pretty slight, then what's the point. The only reason I see for a dove tail is if you're using it for cars, but it doesn't sound like a car trailer.
 

ANGELO

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I have no idea about structure differences. But I would never buy a tube boat trailer ever.
all my company 10+ year old c channel equipment tailers are doing alright while the 2-4 year old box frame enclosed trailers are completely rusted out. C channel would definitely be my choice
 

Benny

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I'm going to build my next bumper pull and I'm torn between 5" 9lb channel or 5x3 x .1875 tube for frame and tongue. Thought about i-beam, but already have a heavy hauler and want to stay reasonably light.

Current idea is 20ft x 83", wrapped tongue, 4ft steel dove, 6k axles. I've quoted multiple brands and their all over $4k+, fuck that.

People keep trying to persuade me to channel because "the tube will rot inside out". Yet I have 70s scout frame and 80s Toyotas that dont have a spec of rust. I figured square tube would be easiest to work with and stay rigid. Instead of having to notch ever mount or crossmember with channel

Engineer friend told me to look at point burden stress tables, but that's little bit above my redneck paygrade.

Not that it really matters, but what do you plan on using for the deck?
 

TRINDU

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unnamed (5).jpg
Not that it really matters, but what do you plan on using for the deck?

I like wood, its forgiving and dorsnt scald your skin in the summers.

I have thought about doing the outside 2ft in perforated steel deck, like so:
 

arse_sidewards

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I'd go with the 5x3 tube. Weld caps on the ends and make sure there is no path for any moisture/air into the interior of the tubes and it will last well enough.
 

KungFooMASTA

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I'd go with the 5x3 tube. Weld caps on the ends and make sure there is no path for any moisture/air into the interior of the tubes and it will last well enough.

Moisture will always find its way in, but sometimes it does not find a way out until it freezes and blows the tubing out. You would be better off to leave the ends open so you could wash it out and it could dry.
 

arse_sidewards

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Moisture will always find its way in, but sometimes it does not find a way out until it freezes and blows the tubing out. You would be better off to leave the ends open so you could wash it out and it could dry.

Bullshit.

I've cut up plenty of old boat trailers made of tube. The cross-members that were welded all the way around and didn't have any holes in them were almost always clean on the inside. The frame rails that were open were always rusted to fuck. This is with powder coated trailers in salt water.
 

Ghetto Fab.

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Hmmmm.... I wonder what the strength and weight difference is between 3x5 0.188 wall and 2x6 0.120wall?

I can tell you that 2x4 0.120 wall is not strong enough for a 7k car trailer.

Kevin
 

87manche

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Bullshit.

I've cut up plenty of old boat trailers made of tube. The cross-members that were welded all the way around and didn't have any holes in them were almost always clean on the inside. The frame rails that were open were always rusted to fuck. This is with powder coated trailers in salt water.

this.
sealed tubes are no issue.

tubes with holes and shit in them will die in the rust belt though. Of course everything dies in the rust belt.

if rust isn't a concern because your state doesn't use 100lbs/mile of salt in a winter everytime it snows, tube.
 

CarterKraft

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Armchair enginerd here going to try and share some BeamBoy load calcs
Don't worry too much about the actual load numbers or support numbers, this is a material strength comparison not trailer design.
I'll add 2x6 tube too I think it will be stronger/lighter than all.

5x3 angle.JPG


5x3 tube.JPG


5 beam.JPG


5x9 channel.JPG
 

TRINDU

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Armchair enginerd here going to try and share some BeamBoy load calcs
Don't worry too much about the actual load numbers or support numbers, this is a material strength comparison not trailer design.
I'll add 2x6 tube too I think it will be stronger/lighter than all.

All of those charts look identical to me. What I'm I looking for? :homer:
 

CarterKraft

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All of those charts look identical to me. What I'm I looking for? :homer:

I probably should have tried to explain :homer:
The picture of the beam just shows the loading, its not representative of the OP's trailer specs but is a comparison of all the beams in the same load.
Don't worry too much about the picture of the stress and deflection worry about the numbers in red for those too parameters. The deflection is probably obvious but the stress is the amount of actual material stress the beam is subjected to. With regular hot rolled steel the suggestion I found was to use 30ksi (30000000psi) and if you exceed that amount the steel will be permanently deformed and not "spring back".
The deflection measurement is just the amount of "bend" when the load is applied. The ideal deflection might be .000" but you have to determine how much is acceptable for your situation. A real engineer would have the loads needed and not use point loads in their calculations.
I usually have a feel for what size steel is needed but I can compare like you are doing here for other materials or cross sections to see if I can save weight, cost or add strength.

beam.JPG


stressdeflection.JPG
 

TRINDU

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I probably should have tried to explain :homer:
The picture of the beam just shows the loading, its not representative of the OP's trailer specs but is a comparison of all the beams in the same load.
Don't worry too much about the picture of the stress and deflection worry about the numbers in red for those too parameters. The deflection is probably obvious but the stress is the amount of actual material stress the beam is subjected to. With regular hot rolled steel the suggestion I found was to use 30ksi (30000000psi) and if you exceed that amount the steel will be permanently deformed and not "spring back".
The deflection measurement is just the amount of "bend" when the load is applied. The ideal deflection might be .000" but you have to determine how much is acceptable for your situation. A real engineer would have the loads needed and not use point loads in their calculations.
I usually have a feel for what size steel is needed but I can compare like you are doing here for other materials or cross sections to see if I can save weight, cost or add strength.

Got it! Much appreciated!

I just used the angle as the base material as that's what my current hauler is now, and clearly unacceptable for my current use.

The material I picked was due to comparable weight. From there I pick what compromise is best. From a weight vs strength and also how easy the material is to manage and build in my own shop. The slight difference in price is negligible. A few hundred overall wont sway me.

5x3 seems to be the best compromise, I was pleasantly surprised to see it was "stronger" than 5x9 channel. Unless my simpleton redneck mind is misunderstanding again :laughing:

edit: need to pull the tables back up and see was 2x6x.188 weighs
 
Last edited:

CarterKraft

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Got it! Much appreciated!

I just used the angle as the base material as that's what my current hauler is now, and clearly unacceptable for my current use.

The material I picked was due to comparable weight. From there I pick what compromise is best. From a weight vs strength and also how easy the material is to manage and build in my own shop. The slight difference in price is negligible. A few hundred overall wont sway me.

5x3 seems to be the best compromise, I was pleasantly surprised to see it was "stronger" than 5x9 channel. Unless my simpleton redneck mind is misunderstanding again :laughing:

edit: need to pull the tables back up and see was 2x6x.188 weighs

I wish I could do real load calc type simulations but I am knowledge limited....

The 2x6 weighs the same as the 5x3 @9.42lb/ft but the 2x6 is stronger. In my experience using this tool (BeamBoy.exe) and steel load tables the taller section is stronger and it takes A LOT of thickness (weigth) to equal that increase in section height.

Case in point, 2x8x.120 is the strongest of ALL the materials listed even the i-beam and it's also the lightest @ 7.83 lb/ft

2x8x10 tube.JPG
 

billybob_81067

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Moisture will always find its way in, but sometimes it does not find a way out until it freezes and blows the tubing out. You would be better off to leave the ends open so you could wash it out and it could dry.

This has been my experience as well, but I also don't live in the rust belt. If I use tubing I make sure to drill drain holes because moisture will find a way in and then freeze and swell the tubing.
 
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