Harbor Freight 4x8 Trailer Rebuild

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I bought this little trailer all of the way back in 2015 to pull behind the Subaru Forester I had at that time. It was $250 from Harbor Freight and I spent around $250 more to put 3/4" plywood beds and sides on it. Since then we've made hundreds of trips to the city yard waste disposal area (leaves and limbs), trips home with appliances, trips hauling tools for other projects, and many other little trips with this trailer. However, using it for yard waste meant that sometimes it would sit outside for a month plus with leaves/yard debris in it. Needless to say, over the past 8+ years it slowly rotted out (and treated lumber kind of sucks these days).
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The current state is below. I ordered just shy of $400 in steel today to re-do the deck with diamond plate and re-make the sides using an angle iron frame and plywood. I could have bought a new trailer ($2K), but I really like the size of this one as it's super easy to move around by hand. Also, with the solid sides and bottom, I've successfully hauled thousands of dollars of tools inside the trailer in the rain and kept them dry by putting a tarp over the top of the trailer and holding it down with roofing nails.
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Cool. I’m currently welding my frame and extended it to 6’ with the original tongue and bed frame rails! Got an 11’ 2x2 tongue to weld on then building a wood box and rack around the whole thing! 3500lb axle and 33” tires.

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Cool. I’m currently welding my frame and extended it to 6’ with the original tongue and bed frame rails! Got an 11’ 2x2 tongue to weld on then building a wood box and rack around the whole thing! 3500lb axle and 33” tires.

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How did these projects turn out? I’m about ready to start my own Harbor Freight trailer project and I’ll be starting off similar to yours, Farnsrocket.

Where’d you position the 2x2 main tube? Did you pierce the cross members, or weld it on underneath?
 
Here is the end product. It was OK. I rebuilt the whole tongue and added diamond plate in the floor.

A few weeks ago I used it to haul about 600 pounds of steel stock home, cut in 10-12 ft lengths, and stored diagonally. This seemed to warp the bed a little bit. I probably should have reinforced the frame a bit more underneath. Or built a new frame from scrap. The frame in these - 1/8" C channel - is just too weak and flexy. I'll bend mine back down with the bucket on the tractor.

It has been a very handy trailer for lumber yard and dump runs.
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How did these projects turn out? I’m about ready to start my own Harbor Freight trailer project and I’ll be starting off similar to yours, Farnsrocket.

Where’d you position the 2x2 main tube? Did you pierce the cross members, or weld it on underneath?
It came really nice and worked great for my family trip to Maine this summer!!
I put the frame right on top of the 2x2 and just welded it at the seams, where it touched from front to back. I had to notch out the frame in a couple of places where the 2x2 didn't quite touch and I added a couple of crossmembers for my shocks.
I reinforced the whole frame with old steel bed frame rails, they worked out great and made it super rigid.
I cut the tongue and added a hitch receiver so I could remove it when I store it in my garage. I also added a rear hitch receiver the back in case I wanted to add a bike carrier for trips (we didn[t use it this time).
I built my box out of regular plywood, 3/4" floor and I think 3/8" on the sides and roof. I tried that poor mans fiberglass to cover it but it was messy and didn't work out so I just primed the box and covered it in good exterior paint. I coated the whole underside in truck bed coating.
I marked my doors and mounted the hinges then cut my doors out with an oscillating multitool and used marine latches. These took a bit of time to frame behind the doors so I could add weather stripping to seal the doors.
I added a couple of tongue boxes to the front and back.
I added a 100ah LiFePO battery with a solar controller and panel. I also added a fuse box and various cut off switches and breakers to make it safe. It powered my 12v cooler throughout the whole 2 week trip!
I was meaning to add some fog lights around the trailer along with an outlet for my propane shower but didn't get around to it before our trip.
I got a Max Coupler articulated hitch. It is a great piece and worked perfectly, very easy to hook up and take off and is dead silent on the road.
I figured out my whole weight distribution thing on our first day out!!! I had originally mounted a Thule cargo box to the top of the rack and had my canoe on my truck. I also had my spare tire mounted off the side of the rack in a mount that I had welded up. That along with the other crap I put in the trailer really made the trailer heavy. Oh, and I also put a 4 bike carrier on the back of the trailer. So when we started driving out of our neighborhood, we hit a speed bump and the whole trailer bottomed out! My wife even noticed it and was like WTH was that? I immediately knew I had to much weigh on it so we turned around and took the bikes off and put them in the garage. Got back out on the road and I could just tell the trailer was too loaded down. It was it swaying in turns and just super heavy on slight dips in the road. I could see the tires almost rubbing the fenders. So we stopped and I got out and could see my leaf springs were almost flat! Dammit, I called a buddy and talked to him about it. He was like you probably have to much weight in it. So, I am pissed that I hadn't taken a test run with it before.............I literally finished up the solar wiring the night before. The wife is just as pissed but we finally rationalized that we would go back, I would fix things and we would just have to skip our camping spot in New York on our way to Maine.
So I moved the Thule box to my truck, put the canoe on the trailer and moved the spare tire up to the tongue where I welded up a new mount.
I also removed some of the heavier items in the trailer to the truck and put more clothing and bedding in the trailer. It worked out perfectly and the trip was amazing.









































 
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Yours looks great with the added reinforcement! Should have done that to mine and I think it would have been quite a bit more robust. I'll probably just start from scratch in the future - the next time this trailer needs something - and only keep the VIN tag and permanent license plate I paid for.
 
Yours looks great with the added reinforcement! Should have done that to mine and I think it would have been quite a bit more robust. I'll probably just start from scratch in the future - the next time this trailer needs something - and only keep the VIN tag and permanent license plate I paid for.
Thanks! Yes it is super strong and sturdy. I would have loved to have started from scratch, but like you said, I had the trailer registered with a VIN/title and a lot of material to build it so it all worked out.
 
Looks good! I’m aiming for something similar, so seeing your pictures is making me want to get started.

I’m surprised that the 3500 lb axle and suspension you upgraded to isn’t enough for how you first loaded it up. I went with a 3500 lb torsion axle, but was toying with the idea of having the axle derated to 3000 lbs when I was putting the axle order together to improve the ride with light loads. I did rough calcs on my anticipated loaded weight, which came out to around 3200. So I decided to go with the full 3500 to give a little cushion. I’m planning to set the fenders 5” off the tires with the trailer empty to make sure there’s always enough clearance to keep them from rubbing. The axle builder provided a suspension travel chart, which helped figure out the fender spacing.

I’m also planning to use angle iron to reinforce the existing frame. But I’m going to run the angle on the bottom to give the axle something more stable to mount to.

When I get moving on my trailer I’ll post pics, but it probably won’t be until spring.., unfortunately there are too many other projects lined up ahead of the trailer.
 

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