TOTU: Thrill of the Unknown Trailer Build

[Boonie Buster]

This trailer project grew from a need and desire to level up our camping and recreation game. We were tired of the daily tear down and setup of our roof top tent when we planned to stay in a location for more than one day. Also, on a trip to Yellowstone a few years ago, we took out kayaks and having them on the roof (over the RTT) presented another problem in which we had to take the kayaks off the truck before we could set up the tent every day or secure the kayaks to a nearby tree with cable locks in camp so they didn’t grow legs and keep our fellow campers honest.

A requirement for the trailer would be the ability to hold most of our toys, whether that be motorcycles, kayaks, bicycles, or future toys like quads or a side by side. Another and more important one would be mounting the roof top tent to the trailer on a rack. I like versatility in my tools, I want them to serve more than one function, and if they don’t, then they have to do a really great job at the one thing they do. The trailer has already seen a lot of use outside of our normal adventures. From hauling the motorcycles, to the trips to the hardware store, and everything in between.

Dimensions and Weights:
12'-0" Deck Length
5'-6" Width between fenders
16'-6" Overall Length
7'-6" Overall Width
1200lb Dry Weight (it's a pig!)
3500lb Axle Rating
2300lb Carry Capacity

1"x6" Ipe Hardwood decking material (beautiful and tough stuff!)

Current Setup:









So now on to the build!

 

[Boonie Buster]

The main structure of the frame is built with 2"x3"x.125" wall rectangle tube and the spanners being 2"x2"x.125"wall sq tube. I started by laying out the rough frame on the floor.

I used a 285/75/26 tire on 17x9 wheel with 4.5" back spacing for initial setup considering this would be the max tire size i planned to use.









The 2x2 sq tube is spaced every 2'-0" which will support the wood decking I planned on using.

 

[Boonie Buster]

Once I had the initial layout figured out it was time to align and tack weld the main frame and stringers. One thing I did change before continuing, was the rear "bumper" was shortened 1'-0" overall so the outside width would be 7'-6" (90"). This would keep the fenders at 12" past the deck and also narrowed the deck width by 6" to an overall width of 5'-6". I didn't want to be so wide as to be close to the max legal trailer width (108" as i recall), but also wider than the utility trailer I have been currently using (5'-0" wood deck).

I used wood chunks of 2x4s and a pack of wood door shims to adjust and level the outer frame, then tack welded the corners in place.



The stringers are flush with the bottom of the 2x3s as I wanted to recess the wood decking (I didnt know exactly what wood or thickness I was going to use at this point)


In hind sight, two things. I wish I had pre-drilled the 2x3 in the rear bumper for wiring, as well as the front corners. Or 45* chamfered the front corners. Either way would have worked, it just proved to be a bit of a struggle down the road when it came time for wiring through the frame.

 

[Boonie Buster]

Once the frame was square, I welded all the surfaces i had access to on the top of the frame, then used the overhead hoist to rotate the frame onto one side to weld the vertical portions of the stringers. This took a little bit of finesse and time by myself to safely rotate the frame around since i needed to do it twice, then place it upside down on the floor for the tongue portion of the trailer.







The tongue portion of the trailer is 2"x3"x.125"wall and extends 4'-0" past the front of the frame and extends 4'-4" into the frame, I wanted to be able to place a nice fillet weld onto this end instead of trying to weld right on the end of the tongue beam. The tongue braces are 2"x2"x.120" and go back at approx 30* angles, these angles took a little bit of work since my chop saw only cuts to a 45* angle.

Not shown in the picture below is the hitch mount, which i test fit to make sure the braces wouldn't interfere.



Once I was happy with the placement of everything, I welded all the edges I had comfortable access to. No need to get fancy when you can flip it around!





While I had the trailer upside down, I took the opportunity to position the Timbren 3500lb HD axleless system, I originally planned to not run a 2"x3" cross beam to keep my ground clearance to a maximum, but I opted for more strength in the end, as the bracing involved to not run a cross beam would interfere with the recessed wood deck I planned. Plus, I had to be realistic with myself, the truck will be bellied out way before the trailer even thinks about it!





And just for layout purposes....

 

[jwiereng]

Nice build.

Why did you decide to make it 5+ ft inside the fenders?

 

[Boonie Buster]

Nice build.

Why did you decide to make it 5+ ft inside the fenders?

I wanted to be able to drive most UTVs or a Suzuki samurai/VW Bug in between the fenders. Or a larger UTV can be driven over the fenders if needed. Plus it makes it way easier to load and unload plywood sheets and other loads having the extra room. I haven’t posted pictures yet, but this is loosely based off the dimensions of a boat trailer my dad built almost 30 yrs ago and we put a wood utility deck on it 5 years ago to help with a move. That wood deck is 5’x10’ as I recall. I found that loading two motorcycles on it had plenty of room, but I wanted more and only made this trailer slightly bigger in overall dimensions with may more function.

There are parts of me that wish it were maybe a full 1’-0” narrower overall. But overall the trailer is 3” wider on each side than the outside of the mirrors on my Tacoma. So if you can drive the truck through something, you can drive the trailer through, hopefully! Ha ha!

Sorry for the long reply!

 

[jwiereng]

Interesting to read about all different reasons people have for building thing the way they do. That is the best part of DIY. Make what you want. Thanks.

 

[TusknRaidr]

This trailer is so rad.

 

[Boonie Buster]

Next step was to add support plates on the inside for the axle bolts so the frame didn't pinch when the bolts were tightened. The flip the trailer over and fully weld the added supports as well as any other welds that were inaccessible.








Then it was time to wrestle the axles into place and temporarily bolt them in place and put the trailer on its own weight.




This is when i realized I didn't want the tires sticking so far out and needed to find a different tire width and wheel combo.

 

[Boonie Buster]

Here's an inside look at the frame plate for the main axle bolts.


You can see where the 2x3x1/4 rect tube will go through for the major support of the axle.





Next up was the tongue jack. Due to the height of the detachable wheel, I wish I had lowered the jack mount by another 2-3". The flat base works perfect. But without a lift kit on the Tacoma, the wheel attachment is just a hair to tall to fully lower the trailer onto the hitch if parked in a weird spot. It hasn't been a major issue since most of the time I use the flat base when setting up at a campsite.

 

[Boonie Buster]

Next was to build the trailer outer platforms. These were 12" outside of the main frame and made of 2x2x.120wall sq tube.



The wheel gap should allow for a 35" tire, but for this style of trailer I don't think it's necessary. Unless someone feels they need to look cool.



Holes were drilled inside before welding so I could route wiring through the frame. If I did this again I would have mitered the corners to allow easier access. The visible welds at the corners and tops were ground flush for platform plating.

 

[girvin]

This is great stuff my trailer is very similer as yours except my cross members are flush with the top instead of the bottom for a flat floor. I have a question running the tongue under the trailer as you have wont work since I have a 1in gap in the underside bc of the 2x2 cross members. I was planing on welding it to the front 2x3 (mine is 3/16) I have seen a few members very vocal about how bad this is. I did a fair bit of heavy equipment repair as a welder and seen big trailers built this way. What are your thought or recomendations

 

[Boonie Buster]

This is great stuff my trailer is very similar as yours except my cross members are flush with the top instead of the bottom for a flat floor. I have a question running the tongue under the trailer as you have wont work since I have a 1in gap in the underside bc of the 2x2 cross members. I was planing on welding it to the front 2x3 (mine is 3/16) I have seen a few members very vocal about how bad this is. I did a fair bit of heavy equipment repair as a welder and seen big trailers built this way. What are your thought or recommendations.

Thanks @girvin

I put my crossmembers flush with the bottom so the top of the boards would be flush with the top of the 2x3s, with the exception of the board caps, which you'll see later when I get that posted.

I preface this by saying I'm a designer, not an engineer. But the reason a lot of people extend the tongue either the entire length or at least back a couple x-members is so there isn't a weak point right at the front of the trailer frame and where the tongue starts. If you're confident in your welding and fabrication skills and it were a lightweight trailer, I probably wouldn't worry too much about welding directly to the front of the trailer box. And to argue that point, myself, I tend to lean to the overbuilt side, I would most likely do what I did on this trailer and at least connect a few crossmembers to the tongue piece for strength. Imagine if you went and picked up a bunch of concrete for a project and loaded it at the front edge of your trailer, you'd have a lot of weight right at a weld seam with no support other than the weld.

If I were you, I'd maybe notch my front 2x3 and run the tongue back at least one x-member and do some side supports to the tongue at an angle, or go back two or three x-members if I didn't plan to support the tongue in any other way.

I don't agree with you that heavy equipment trailers are built with the tongue welded to the front of the trailer bed, I'm sure some are though. If you look at them closely, they have two beams that run parallel under the trailer bed for additional bed strength before heading forward and tying together at a 30* tongue attachment. This seems like a typical design for trailers that most common trucks could tow, not including Semi's since most of us on the forum probably don't have one in our driveways.

Disclaimer: These are my opinions and observations. Things that work for me, may not work for you.

 

[girvin]

Thanks alot for the advice I am leaning towards the notching as it is a nice compromise. Cheers! its usually the lowboys that had that flush tongue I am sure it goes back aways I am usually welding on the back though as thats where its usually broken

 

[Boonie Buster]

Thanks alot for the advice I am leaning towards the notching as it is a nice compromise. Cheers! its usually the lowboys that had that flush tongue I am sure it goes back aways I am usually welding on the back though as thats where its usually broken

Were you repairing the tongues of heavy equipment trailers that failed at the welds?