Building my own trailer - need some advice

[verbotenwhisky]

I’ve tried hard not to say anything. I’m all about people building what they need or want BUT if you’re not 100 percent sure your welding skills can take the stress of road conditions I wouldn’t build something being towed on public roads that if it fails it could hurt or kill others. I overbuild trailers. Gussets. Brackets. Overlaps til I’m positive in worse cases it won’t fail. And I’m perfectly happy with my welding skills.

You will not require a lawyer, more than not the trailer, due to the law, is not only attached with the ball but also chains and, when the stool sample plows through the air mover, the trailer will snag flip and roll the tow vehicle killing you and those with you first then others not agile enough to avoid your aftermath; your estate however, may not be distributed as you had planned....

 

[RJSakowski]

Trailer waggle or fish tail is generally a load issue but a strong gust of wind or a semi will get your attention. surge breaks are okay but I always put a break controller on my tow vehicles the newer pendulum types work as good as the old hydraulic over electric controllers and do not require a tap into your break system. if you get waggle for any reason you reach down and manually pull the breaks to tension the trailer without breaking the tow vehicle and the weight of the trailer will straighten you out. If it is a load distribution issue (usually is) you'll need to stop, clean out your shorts and redistribute some weight forward of the axle.

That is one advantage of electric brakes.

I opted for the Surge brakes because they were independent of the tow vehicle. I use disk brakes in the trailer above but had a hydraulic bypass solenoid valve that was activated by the backup lights. The valve was actually a high pressure fuel valve from a jet plane. It worked out very well in that application. With the dropped axle and the Surge brakes, I hardy knew the trailer was there. Wind resistance was virtually eliminated as the boat was only slightly above the top of the truck.

 

[Firstram]

Yeah water... If something does happen I can dump it out to reduce weight.

9000lb axle, 8000lbs of payload on the rare occasion I'm actually maxed...

half ton truck with 9500lbs towing capacity, actually towing 8000lbs...

I'm sorry but I just don't see the problem here, if someone would like to explain it that'd be great. A whole lotta people saying it's a bad idea, but not specifically why. All the numbers seem to add up to me...

There is a reason you don't see single axle trailers above a certain weight, stability!
What you are describing and planning to do will not end well. You should go rent a U-Haul trailer, load it up with stacked totes of water and take it for a spin. If you can't visualize what will happen during an emergency situation, you shouldn't be doing this.

 

[Ultradog MN]

I did a quick look around for the CVWR or GVWR for a 1500 and didn't readily find it.
There should be a sticker in your door or maybe someone here has it at their fingertips.
Your 9500 sounds about right but I'm thinking that is your GVWR not the weight you can pull.
As for the one axle vs two...
I learned the reason you want two axles when I was still playing on these things.
Seriously, you want a tandem to haul that much weight.

Rereading this thread makes me think of a couple of things.
First
You probably ARE in the zone for what weight you can pull with a 1500.
Second
The wider track width on a heavier axle may be some concern but whether it has duals or not wouldn't make a difference.
The maximum width of any vehicle on the road is 102".
That includes even big semis (except by permit)
My trailer tires measure right at 102" outside to outside of the tires. If I were to put duals on the trailer it still couldn't be wider.
I just measured outside to outside of the tires on my 2500 Chevy - in the dark on wet pavement so maybe not exact. They are 79 or 80".
That means the trailer tires are about 13" closer to the curb than my PU tires.
I have never found that to be an issue as you grow accustomed to swinging wider in a turn and not nudging the curb with the pickup tires when you park.
I suspect a 1500 is about the same width at the tires so not a big issue IMO.
Third
My concern with his trailer goes back to the single axle. And I did not post the photo of the teeter totter to insult anyone BTW but to make a visual point about a fulcrum.
Lets take a trailer and place 9000 lbs Exactly in the center of the axle/ fulcrum.

When perfectly balanced there would be zero weight on the tongue.
But let's say we're going down a road with humps and dips. As that fulcrum teeter totters back and forth there could be anything from overload on the ball hitch to the tongue tending to lift the pickup's rear tires off the ground.
Yes, the length of the tongue reduces the amount of weighting/lifting on the ball but it would require a much heavier tongue.
And imagine if you were backing the trailer up and hit a rock or stump with the trailer tires. That fulcrum could actually lift the PU's rear tires off the ground. Wouldn't that be cute
A tandem trailer still is/has a fulcrum but the fulcrum is vastly less "teeter tottery".

 

[verbotenwhisky]

Last year I bought a 5x8 utility trailer and upgraded the heck out of it while teaching myself how to weld. Well now I enjoyed that so much I want to try something bigger.
I plan on building a pressure washing, hydroseeding, and fire fighting trailer unit, gonna have a skid mount hydroseeder, a big pressure washer, a water pump, and 2 ibc totes full of water.

The majority of the weight on the trailer will be about 5500lbs of water when its full (assuming 2 full 330 gallon ibc totes), and that plus all the equipment I figure to be safe that's about 7000lbs total, so I'm thinking an 8000 or 9000lb axle.

With leaf springs do I get them by the weight rating on the spring or on the axle? Would I get 2 8000lb springs for a trailer with a 8000lb axle, or would I get 2 4000lb springs for it? What do y'all suggest for the main frame / body of the trailer? Is C channel enough or should I go for square tubing? What thickness? I'm really new to metalworking in general and want to make sure to overbuild everything for safety since I'll be driving it on the road. If I need 3 1/4" angle iron braces I'll put 4 3/8" braces...

Is there some guide or source material I can read that will teach me how to calculate the weight a given profile needs to permanently deform? I want to learn how to pick/calculate what thickness material I need for a given project.

Please note that when the good folk here discuss dual(s) they are not referring to dual wheels as in the back of a 1 ton duly or a semi, the proper terminology is tandem axles. You can put a single axle under this easy enough but you should not! your dealing with a heavy dynamic load a single blow out will likely ruin more than your day on the single axle version; but, on the tandem axle version it'll be an irritation that will force you to pull over and change a tire which you will be able to do.

 

[tq60]

2 axles are more stable, load supported by 4 places and not 2.

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[7milesup]

IDGAF about a break away system either but that's cheap and easy to add later... All I need to get it road legal is the trailer itself, a weight slip, and a superficial "inspection", and I may not even mess with that since the trailer is gonna spend its whole life in a small rural area with a ton of private roads, but for safety I would like to build it good enough to be road legal.

How about you don't plan on taking it on ANY public road. Maybe from the back of your property to the mailbox. This is a disaster waiting to happen.

 

[Larry$]

It's obvious that experience of others is not wanted. I resisted commenting but finally think I need to ad my bit to the pile in the corner. Just to provide some background, I do have enough experience to comment. My own pickup (F250) was equipped with load equalizing bars & anti sway (fishtail) and extra heavy tires. I pulled a Bobcat & dump trailers w/breakaway. I also used a similarly equipped F250 to pull 38' mobil homes from a manufacturer to dealers for several years. 400 miles! Pushing the limits for an F250. It wasn't the weight, it was the wind. Single and tandem dump trucks with pintle hooks & assorted trailers. And my favorite a tri-axle Mack pulling a 3 axle lowboy loaded high & over width. I had close calls with almost every one. It happens in 1000s of miles & years of doing it, or on your first trip! Usually at the worst possible time. Plan for it. About hauling water, keep the containers full! Free surface quickly adds to instability. Do not stack water, the free surface in the top container will really cause instability even at very slow speeds. We had a 6,000 gallon trailer used to haul water on heavy construction sites. That thing would wag the Mack's tail if not filled to the top. The weight of the water always shifts to the least desirable side and there isn't anything you can do, in time, once it starts. Buy a trailer! A GM 1500 pickup is a lot less than an ideal tow truck in spite of what they say it can pull (in a straight line.)

 

[tq60]

Something we saw at the farm show years ago was plastic stuff that went inside tanks for hauling liquid, looked like large swirls of plastic, designed to just be pushed through access hole, it made for less sloshing on roadway, hitting bakes or a curve in the road will bring Newton up to ruin your day.

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[deakin]

IMHO Building a trailer of that weight class is not trivial, welds will be subject to high dynamic stress and the size and shape of materials should be carefully considered. Perhaps there are some plans available for proven frame design that you can use as a foundation for your project?
Here in New York, any home built trailer must receive a special inspection and you must present receipts for all materials used in its construction. I surmise the latter requirement is to prevent people trying to pass off a stolen trailer as home built.

i believe you will find that receipts are required to prove you paid tax to the state

if you were to build a custom car or bike you are required to present receipts to show tax was paid