DIY Trailer - Build/Fabrication Questions

[Uglyduck]

ExPo has some awesome fabricators and I was hoping to glean some input from them. I'm working up plans for a trailer build that some friends and I will fab but I don't know how to weld and they've never built a trailer before...it should be interesting.

It'll have a 4'W x 6'L x 2'H box but I'm unsure of what size square tubing would be ideal for strength and weight savings for the main box.

Would 1" with 1/8 wall thickness be sufficient? What about using angle iron?

Also, would a C channel frame be strong enough or should I go with a boxed in design?

Below is a Sketchup rendering to help you visualize it


Thanks for your advice!

 

[tclaremont]

For the most part, the answer will depend on your plans for the trailer. How much weight will you be carrying? Across nothing but asphalt, or up the side of a rocky cliff? Your plans will dictate your build.

 

[goodtimes]

Angle and c-channel are pretty common in commercial trailers. Relative to square (or rectangular) tube - it's cheap & light. It also isn't as durable. Depending on what you do with the trailer - that may or may not be a problem. Stop by a trailer sales place and look around. Look under the commercial trailers and see how they're put together. If nothing else, it will give you an idea for a starting point.

When I built my motorcycle/utility trailer, I used 2 x 4 x .120" HREW tube. 2 x 4 is a pretty convenient size to work with. Spring hangers, lights, etc all fit without building extra tabs and mounts, saving that headache and keeping the lines clean. .120 (1/8") is thick enough that when mounting tie-down loops (etc), thread cutting screws have enough material to work with, eliminating the need to weld them on.

Up-size the axle, downsize the springs. Use shocks & as big of a tire as practical.

For a total load of about 1200 pounds (2 motorcycles, gear, + the trailer itself), I used 1250# springs & a 3500# axle, 205/75 tires (IIRC).

Be careful with weight - if you make it too light relative to the spring rate, the suspension won't work. 1250 pound spring were the lightest I could find locally. With the trailer unloaded (about 500 pounds), it bounces all over the place, despite running near 20psi in the tires. It needs a little weight on it to make the springs work. If the suspension doesn't work - it transfers all that energy into the frame & box, which isn't a good thing.

 

[Uglyduck]

For the most part, the answer will depend on your plans for the trailer. How much weight will you be carrying? Across nothing but asphalt, or up the side of a rocky cliff? Your plans will dictate your build.

I guestimate equipment load to be between 500-750 lbs at most, but probably closer to the lower end of that range. Sorry, I know thats a broad range. I plan on mounting our Eezi Awn 1600 to the top, a Yeti 75qt cooler on the tongue, Awning on the drivers side, and the chuck box and other equipment loaded inside. The idea is to make it easier to depart on short trips with the family by having the trailer loaded and ready to go but also capable enough to go where others can't.

Most of the local backroads are somewhat maintained fire roads that are in decent shape. However, it needs to be cable of handling slow going rocky terrain as well but not rock crawling. Its certainly not intended to be a pavement queen although it will travel highways enroute to a destination. My truck is still stock which limits our capabilities but I plan on changing that in the future and I'd like to plan the trailer build to compliment the truck, even if its eventual.

Up-size the axle, downsize the springs. Use shocks & as big of a tire as practical.

For a total load of about 1200 pounds (2 motorcycles, gear, + the trailer itself), I used 1250# springs & a 3500# axle, 205/75 tires (IIRC).

All great info GT! Those are the tidbits I was looking for. I think I understand the logic but can you explain the reason for using the 3500lb axle vs. one matched to the load like the springs?

P.S. I'm always happy to "meet" another Az ExPo'er!

 

[goodtimes]

I think I understand the logic but can you explain the reason for using the 3500lb axle vs. one matched to the load like the springs?

A 3500# axle has a much bigger hub/bearing set than a 1500# axle.

 

[skersfan]

For that size frame the most you would ever need its 2x2 box tubing 120 wall. I would stay away from angle iron, except for places like lid rails and all.

Your main runner/tongue should be 2.5x2.5 240 wall, that will allow you to put a articulating coupler on the trailer. Look at all axle combinations, not only leaf spring. Your over all weight is going to be about 1000 pounds less axle and wheels. Dexter Torflex offers and axle with six bolt heavier hubs and bearings on their 2000 pound axle. I would look at electric brakes for the trailer, not because you need them on road, but off road the trailer can start to slide and push the vehicle on off camber type stuff, or loose gravel/sand, having the ability to control the trailer by hand levers is a god send, seldom needed, but when it is, you will thank God you have them.

You live in the home of the Overland Expo which is next month. There will be several trailer builders there, I would stop by and look at all of them, pick their brains and see what works best with your ideas. We will be in booth/site 53, do not hesitate to stop by.

 

[Uglyduck]

For that size frame the most you would ever need its 2x2 box tubing 120 wall. I would stay away from angle iron, except for places like lid rails and all.

Why stay from angle iron? I'm not arguing it, just curious because my buddy doing the welding is convinced it'll be fine and I'm no engineer (well....not that kind at least, I'm a fire engine kind of engineer) so I don't know enough about the topic to argue otherwise. He's also not an overland sort of guy, more of an RV type, so he isn't familiar with these trailers or their design. He suggested using angle iron for the frame on the box with square tube for the center supports.

Your main runner/tongue should be 2.5x2.5 240 wall, that will allow you to put a articulating coupler on the trailer. Look at all axle combinations, not only leaf spring. Your over all weight is going to be about 1000 pounds less axle and wheels. Dexter Torflex offers and axle with six bolt heavier hubs and bearings on their 2000 pound axle. I would look at electric brakes for the trailer, not because you need them on road, but off road the trailer can start to slide and push the vehicle on off camber type stuff, or loose gravel/sand, having the ability to control the trailer by hand levers is a god send, seldom needed, but when it is, you will thank God you have them.

Its ironic that you brought up trailer brakes because we were just discussing them! Is it possible to upgrade to brakes later or does it require a special axle setup that I should get from the beginning? Also, should I investigate a hand brake setup as well or do the electrics essentially take care of that?

You live in the home of the Overland Expo which is next month. There will be several trailer builders there, I would stop by and look at all of them, pick their brains and see what works best with your ideas. We will be in booth/site 53, do not hesitate to stop by.

Again...ironic that you mention the O.Expo. I took some time off to attend and am planning on staying at the Mo Lake Ranger station which is a little walk across the "lake" from the Expo. I set an unofficial deadline in my head to get a trailer done (or mostly done) by then so the Expo can be its maiden voyage. That might be a little ambitious but I have 4 guys willing to help so I'm hopeful.

I'd love to see a few first hand at the Expo but my mental deadline doesn't jive. I'm optimistic about completing it by then but in reality it may not be done. Either way, I'll be lurking around and we'll be certain to meet!

 

[skersfan]

Angle iron on the uppper holding the sides is okay. I just never use if for anything where structure and strength are important. It bends easily and does not spring back like box tubing. And in honesty does not save much money on a trailer this size. The upper box does make the trailer stronger if it is built to do that. I would never use it for the main frame, channel is accepted and used on many trailers, but I have learned over the years the box tubing is the best for my uses and is easier to work with. Some people over build with box tubing. It is very strong and if welded and braced right it is almost impossible to bend it.

You will need to order the axle for brakes, the axle lengthe will be longer with brakes as the face plate moves outward some. But being close is all that really matters, be sure that you have adequate movement fot the tire and wheel to move up at an inward angle with springs. You do not want it hitting the side of the trailer on severe bumps if possible.

 

[UK4X4]

Box section for the frame if you want a strong ridgid one- angle iron flex's and twists unless braced

you may plan to only pack lightly......but down the road you'll be adding

For example 4 gerry cans of fluid - is 160lbs roughly-oh I want a dirt bike add 300lbs

before you know where you are, your carrying a 500lbs .

My build is here, and should give you an idea on the structure that most of us have built, my steel sizes came from Resarfs build.

All the steel from mine was cut offs from the local steel yard bought by the LB rather than new 5 meter lengths

http://www.expeditionportal.com/forum/threads/12092-Trailer-build-thread-consolidated

 

[Uglyduck]

Ha! Pack lightly! Not with wife, daughter and two dogs! might as well have a dirt bike on it

From the little research I've done the Torflex doesn't appear much more expensive than a leaf suspension and axle. Has that been your experience?

How much drop from the start angle is best for our application? 45 degrees?

 

[skersfan]

45 degree is what you want, it is considered a 6 inch drop. The Torflex makes the frame much strongers as it is a massive crossmember with solid brackets on each main rail. You can order with electric brakes and parking brake mechanics, but they do not provide ahandle for the parking/emergency brake

They are considerably more than a standard axle though. I think the ones I use with electric brakes (normally 2700 pound axle with 3500 gear) runs close to 550.00 the parking brake runs a little more.'

You just do not want to get to much axle with a torsion axle. They are set a certain weight and there is not much you can do to change them. They will be very bouncy if you over go the expected trailer weight, too correct you can lower the air preasure, but try to get close to your maximum weight of the trailer with the axle. They make them under 2000 pounds with 6 lug hubs I think, but have never ordered one.

 

[Uglyduck]

I called Dexter today to get some help spec'ing an axle with leaf springs and the torflex. According to the service center I can only get a 6 lug to match my Tacoma in a 2000lb configuration which may be overkill for this trailer. I can get a lower load capacity but it will be a 5 lug.

How do I figure out the proper hub face distance?

 

[skersfan]

hub face

Dexter has a formula for figuring it.

You will need to know the outside of the main frame rails, distance between both. How much clearance you want between the torsion arm and the side of the trailer, the depth of offset of the wheel you plan to use.

Your sales guy will be able to figure it for you. The great part about the TorFlex is that the wheel only travels up and down, there are no sideways twists, just be sure you have enough room for a good sized rock to pass between the tire and the side of the trailer as it happens quite often. I allow about 3.5 inches for sidewall of tire to side of trailer.

 

[goodtimes]

How do I figure out the proper hub face distance?

Best advice for that is to build the trailer (well, the frame & fenders anyway), set the tires where you want them, then measure the face to face distance. That way you're covered if something changes during construction.

 

[Uglyduck]

Thanks GT!

Another question, I noticed that Sierra 4x4 sells a suspension kit designed for 43" springs and most off the shelf trailer springs are smaller than that. Whats the advantage to the longer springs?

http://www.sierra4x4trailers.com/category/products/trailer-parts/