Introduction: Off-road Adventure Expedition Trailer for Overlanding
I love the outdoors. I go camping and exploring every chance I get. I also work as an archaeologist, which means I get to spend more nights in a tent than most people. I always wished I could just have everything packed and ready to go at a moment's notice. When I saw my first "expedition trailer" in a magazine, I was blown away. This was EXACTLY what I needed. Then I saw the price. Some of these things go for as much as $15,000! Who has two thumbs and can't afford that? THIS GUY! So I decided to build one myself. And by "I" and "myself," I mean my dad and I. He's a welder, which comes in handy, as you'll see.
A few caveats: This is my first instructable. I didn't even know about this awesome site until after the trailer was done. I don't have any in-progress photos, so I tried to recreate the process with Sketchup. I'm doing this instructable because so many people ask me how we built the trailer. So that's what I'm documenting here: how we did it. That's not to say we did everything perfectly. In retrospect, we could have saved ourselves blood, sweat, tears, time, and money by doing things differently. Overall, it worked out beautifully and it's never failed me and I'm thrilled with it. There are many options, depending on your budget and tastes. I prefer the repurpose/upscale approach, as you'll see. If you decide to build your own expedition trailer, you should make it the way you want it. Hopefully this will give you a few ideas, but its only real purpose is to document how WE MADE THIS ONE.
Step 1: Trailer Body
We started with the primary platform. Most guys who make their own trailer use military surplus trailers. These are tough as hell, but also heavy and expensive. If I had the money, I would go in that direction. I didn't have the money, so I got the bed off a 1947 International Harvester stepside pickup. It had been converted into a trash trailer and was missing its fenders. The tires were bald but there was no rust and it was titled. I got it off Craigslist for $250.
Step 2: Trailer Frame
When I got the trailer, I had no reason to believe its frame wouldn't suffice. It was raining when I bought it and the rain was, I'm sure, percolating garbage juice down through the still-filled-with-trash bed, so I didn't crawl underneath. Well, the frame was not in good shape. At least half of it was made of 2x4s, in fact. So the frame came off and we fabricated a new one out of box steel. This was a financial setback because we went with mostly new steel for the frame. I think it cost around $200.
Something to keep in mind is that backing this thing up is, well, challenging. The slightest turn of your steering wheel has immediate and dramatic effects. This can be mitigated by extending the frame's tongue, but that's a trade-off. Just something to consider.
Step 3: Trailer Hitch
We next mounted a trailer hitch in order to be able to tow this thing. You can use a simple ball hitch, but in rough terrain these can bind up and pop off. For this reason, I went with a pintle hitch. I found a hitch (not shown) and ring (shown) combo on Craigslist for $45. It's marked as U.S. Air Force property, with a 10,000 lb rating. When hooked up, this setup basically consists of two interlocking rings. This gives you nearly unlimited range of motion, with no risk of decoupling.
We could have welded the ring straight to the tongue, but wanted a little more design flexibility than that. You can see in one picture where we built a channel receiver for the ring to "plug in to." We used two pieces of angle iron and had to grind some off the joining edges so that when welded together, the channel would be just wide enough to accept the ring. We cut three sets of holes at different elevations, allowing for the ring to be moved up or down, depending on the height of the tow vehicle.
Step 4: Suspension
As it turns out, 1947 IH suspensions are not off-road worthy. In fact, they are not even on-road worthy. The axle kept vomiting bearings out one end and one of the single-leaf leaf springs snapped. We went to a junk yard and paid $50 for a rear axle, with springs attached. The differential gears were missing, but that's fine; we don't need them. A trailer axle (i.e., no pumpkin) would have given us more clearance in the center, but would not have been as strong (or cheap).
The spring perches on the new axle did not line up with the new frame, so we torched them off and put new ones directly under the outermost frame tubes. We took a long time to ensure everything was perfectly straight. If the axle was off even just a little bit it would put undo wear on the tires.
Speaking of tires, I used the bald ones for awhile but when my student loans came in I bought a set of off-road tires from Big-O with a lifetime road hazard warranty.
Step 5: Sleeping Bag Storage
I found a surplus missile crate on Craigslist for $35 and welded it to the front of the frame, just forward of the bulkhead. The box is entirely waterproof, so I stash sleeping bags in here year round. Make sure you leave enough room between the box and the bulkhead so that you can open the box without dislocating a wrist.
Step 6: Spare Tire Carrier
I ran across a spare tire carrier at a thrift store and picked it up for $15. It doesn't look like the one I've drawn here, but I couldn't find a more realistic one on Sketchup. The one I got is made of bent metal tubing and was designed to fit on the back of an SUV and swing off to one side. We cut off the swinging hinges and welded the ends to a piece of angle iron, which was then welded to the frame. The three lugs on the carrier did not match the bolt pattern of my wheels so we cut two of them off and re-welded them so that they did line up.
Step 7: Internal Support Frame
We knew we were going to be adding some weight above the bed and suspected that the bed itself wouldn't be able to support it all. Thus, we built a frame within the bed. The ladder-like sides have "rungs" made of pipe sections. These are welded between lengths of angle iron. In one photo, I've made the tops of these sections red to draw your attention to them. It's important that these surfaces are exactly the same elevation as the highest point of the bed railing. Once the "ladders" were welded in place, pieces of angle iron were welded across the bed, between the two "ladders." You'll notice that these cross-members are not evenly spaced. Their spacing will make sense in the next step.
Step 8: Slide-Out Drawer System
I bought a slide-out tool drawer system off Craigslist for $75. These are made to fit in pickup truck beds, where they mount to the floor. When you open the tailgate, you can unlock the drawer and pull it out, accessing tools and parts. They're super heavy-duty and damn near impregnable. I figured this would be the perfect place to store smaller camping supplies like hatchets, dishes, first aid kit, etc. The one I got was a "Pack Rat" by WeatherGuard, but several tool box companies make them. New, they run about $1,000, so you'll want to find a good used one. Mine didn't come with a key, but I took it to a locksmith and got it re-keyed for $10.
Anyway, we welded this box directly onto the internal frame. Now you see why the cross-members were spaced like they were. We decided to have the drawers facing to the passenger side so that if we stopped on the highway shoulder to get something we wouldn't be standing out in traffic when we opened it up. We mounted the box far enough to the right that it overhangs the bed rail a bit, to keep rain from being funneled in.
Step 9: Sealing Off the Bed Box
We next used scrap plate steel to seal off the parts of the bed that weren't covered by the Pack Rat and tail gate. This created a couple small platforms on two sides of the Pack Rat. These can be used as kitchen spaces, bike mounts, or lashing extra cargo. Once everything was welded in place, we sealed off cracks with silicone. The bed box is now accessible only through the tail gate. I keep larger items in here, like ice chests, folding chairs, and lanterns. The tail gate is secured with a padlock.
Step 10: Rooftop Tent
I already had a rooftop tent that was mounted on my truck. I wanted to move it to the trailer. These tents are pretty pricey, but they are way more durable than the average tent and should last for years and years. I got mine from Camping Lab but there are several companies that make them now. I also see them for sale used on Craigslist and Ebay.
I found a set of Yakima cross bars and mounting towers at Goodwill for $20! I dismantled the towers and retained the parts that could be mounted directly to the Pack Rat. I did this with heavy duty bolts. They were short enough that they don't interfere with the opening and closing of the Pack Rat drawer. The tent then mounted directly to the cross bars. I mounted the tent so that it unfolds toward the driver's side. This way, at camp, you don't have to duck down under the unfolded tent in order to access the Pack Rat drawers.
Step 11: Tongue Jack
I found a 4,000 lb tongue jack on Craigslist for $8 and we welded that to the tongue. It seemed like a brilliant idea at the time. However, my son and I were up on the Navajo reservation a few weeks later and a washboard road apparently dismantled the jack's guts, causing it to drop down while we were driving. It struck the hardpacked dirt road and bent backwards before I could stop. Luckily, the only thing broken or bent was the jack's leg. It wouldn't go back into the sleeve because it was bent. There wasn't enough room to pull it out the bottom of the sleeve. Finally, we unhitched the trailer and jacked up the tongue with a Hi-Lift until we could yank the leg completely out of the sleeve. At this point, we still have the sleeve welded awkwardly in place but doing nothing other than looking pathetic and reducing clearance. In retrospect, I should have found one of those fold-up tongue jacks that would be out of the way during transport. As it is, we now use a little jack stand. It doesn't do my back any favors, but I can lift the tongue up off the hitch, over a couple inches to the side, and down onto the jack stand. I got wheel chocks at Harbor Freight and use these to keep the trailer from moving any time it's not hitched to the truck.
Step 12: Rear Platform Rack
I happened to run across a great deal on half of a Yakima Load Warrior roof basket. I don't know where the other half went, but it drove the price point down and I couldn't pass it up. Again using parts from Yakima mounting towers, I bolted this thing directly onto the rear platform. I can throw gas cans, water jugs, duffel bags, or coolers up here and cinch them down.
Step 13: Fenders
Per state law or something, I guess you're supposed to have fenders. I had an old surplus ammo box that opened into two equal halves. I bolted these halves above the tires to serve as fenders. So far, so good. Personally, I like the "make do with what you've got" look.
Step 14: Lights and Wiring
Last but not least, we hooked up some tail lights. I got a temporary wiring harness (for towing cars) from Harbor Freight, along with some generic tail lights. We ran the wires down the central frame channel (i.e., tongue). They come out the back and attach to the lights. In front, we drilled a hole in the tongue for the wires to exit and attach to the socket in my truck's bumper.
And there you have it. Now, whenever I get the urge to go camping or I head into the field, all I have to do is hook up the trailer and drive off. No packing to do because everything is already packed! I have a Coleman stove in one of the Pack Rat drawers, so setting up camp, from tent to kitchen, takes about five minutes.
I'd love to see other home-grown expedition trailer projects. Take care and have fun!
Below are credits for Sketchup components:
Truck bed from “International Harvester R110” by Coyote56
Tailgate from “GMC – Old Truck – Deluxe Edition – V8” by arthurnpb
Tailgate chains from “chain sex1” by b.w.schumacher
Pintle hitch includes geometry from “Mr. Donut” by SuperNikki346
Hitch pin from “Trailer Hitch” by josh
Leaf spring hangers from “Spring Hanger for Leaf Spring” by jrcowell
Suspension, wheels and tires from “Browning Camo Stepside Silverado 4x4 chassis” by Chevymanmotors
Tongue box and fenders from “7.62x39 Ammunition Crate” by Brad M.
Spare tire mount from “Rear Bumper and Tire Carrier CJ7” by Gemiel
Tent mounts from “Roof Racks” by Joey B., crediting Reddi
Tongue jack from “Trailer Jack” by jrcowell
Rack from “Roof Rack for my fortuner” by Kenny Pham
Tail lights from “led tail light for trailer” by TRUCK-KID
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