Off Road Trailer Build (1 Viewer)

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UZJ40

OEM(ish)
SILVER Star
Joined
Aug 8, 2011
Threads
235
Messages
2,493
Location
LV, NV
After 5 years of building my 76 FJ40, I am ready to start another project. I have come to the realization that the dog and wife (neither of which I had when I purchased the FJ40), plus all the camping gear, would not fit. It was either take the 4Runner or Tundra to camp, or build a trailer for the 40. Well, I decided to build a trailer!

Tow vehicle-

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Cutting and measuring-

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Undercarriage parts from Croft trailer supply, including 6x5.5 hubs!

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Trying to get an idea of height-

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Planning/layout-

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Water tank placement-

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Tacking everything together-

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Rolling trailer! (kind of)-

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I found a tongue box I thought I'd use, but after looking at it, I'll just make my own. There are a few things I don't like about it that I can fix with my own design.

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Making fenders from scratch. They are the same angle/width/height of my 40's rear fender openings-

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I made the trailer tongue removable so I could fit he trailer and 40 in one my garage parking spots! It fits with about 2" to spare!
 
what spring ratings are you using?
 
Am I understanding this correctly, your are using 1300lb springs (3600 lbs total) for a 1100lb trailer? What do you think your total weight will be when loaded? I think you trailer will bounce all over the place from too much spring. My trail weight is around 1250lbs full loaded, I had 700lbs springs (1400lbs total), about 26" long and and it bounced around and damaged items inside. After around 26k miles both springs broke. For what I have been told, you should be around 80-90% total weight of your springs and longer springs will make a big difference also.

So I would say to revisit the springs while your in the build process. Think about what rate springs you have on your FJ and how much weight they carry.

My build Off road trailer

Look close at the first picture, you can see the break. Both side broke a day apart. Also at the end, shows the new airbag system.
Trailer spring failure



P.S. I do like your work, I think you will have a great trailer when done.
 
@coops2k Did you have shocks on your original setup?
 
I did not.
 
I'll second changing the springs. I'd look at using the longest spring that will fit the frame, whatever that might be. Can always remove shorter leaves from the stack to reduce the rate, but when the main leaf is that short it won't matter as it won't do enough.

Consider buying brakes that have a parking brake function. There have been several times that I really wished for that!

What is the plan for a coupler?
 
Am I understanding this correctly, your are using 1300lb springs (3600 lbs total) for a 1100lb trailer? What do you think your total weight will be when loaded? I think you trailer will bounce all over the place from too much spring. My trail weight is around 1250lbs full loaded, I had 700lbs springs (1400lbs total), about 26" long and and it bounced around and damaged items inside. After around 26k miles both springs broke. For what I have been told, you should be around 80-90% total weight of your springs and longer springs will make a big difference also.

So I would say to revisit the springs while your in the build process. Think about what rate springs you have on your FJ and how much weight they carry.

My build Off road trailer

Look close at the first picture, you can see the break. Both side broke a day apart. Also at the end, shows the new airbag system.
Trailer spring failure



P.S. I do like your work, I think you will have a great trailer when done.

Thanks for your input on the springs!

Yes, you are reading that correct. The 3600lb springs were the lowest capacity I could find from the source I got everything from in a non-slipper-spring setup, which I did not want to use. I can always take a leaf out of the pack, but it's difficult to add them.

These are the same springs I had on a small 5x8 utility trailer that bounced around when empty, but was great with a small load on it.

I also think that shocks are necessary for an off road trailer setup. Many car and flatbed trailers use the vehicle's they're loaded with's suspension to dampen the load, and 99% of trailers will never be taken off road. I am not surprised at all that your springs broke on an off road trailer setup with no shocks, and it bounced all over. Difference springs rates may improve that condition, but shocks will definitely control the bounce.

My plan was to get everything installed and loaded up, take it for a drive, and adjust accordingly. More than likely, I'll remove the middle leaf.
 
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Typical trailer springs are short and stiff so that they A) don't change ride height much between loaded and unloaded & B) so that they don't need dampers. I suspect that even with the middle leaf removed it will still be too stiff unladen, that main leaf is too short for it to be much else. If the suspension doesn't move there's nothing for a damper to do.
 
Getting ready to skin the trailer!

Got the 3 jack mounts welded on and all other welds burned in. Took the fenders off as they will be attached to the 14g skin once it's on.

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Will be skinning the trailer this afternoon. More pictures to come soon!
 
Beautiful 40, beautiful garage and a great looking trailer coming together. I am envious of all of that! Strong work
 
are you putting in a slide? whats the plan to get stuff in the front? very nice work.
 
There are 2 doors in the front for access to the bed storage, one on each side. My original plan was to have a hinged lid, but with the tent on top, the tall sides, and the wide fenders, it would be too difficult for me (or my wife) to access things in the bed area. It seems most off road trailers have a hinged top, so I was going that direction because it seemed popular, but the more I thought about it, the more I didn't like it (for the same reasons I hate tonneau covers on truck beds).

The back swing out will have a fold down table on it, and when opened, it will gain access to a slide out fridge, drawers, and a slide out stove.

The 2 front doors on the 45 degree angles will be used to access everything in the bed since the 'kitchen' will block access from the back. Both doors are 24x24". The only thing I haven't decided yet is if I will have 2 compartments in the bed area (one for each door, a small one behind the fridge, and a larger behind the stove), or one big open space. As much as I like open space, the thought of firewood mixing with the rest of our camping gear doesn't sit well.
 
Very well thought out...i think I'd match the tailers on the truck with the reverse lights.

Very handy backing up at night.

Beautiful workmanship.
 
Would you say it would save a lot of money to build my own trailer vs buying one with some acc already installed? I would also need to purchase all the welding equipment as well...
 
Thanks for your input on the springs!

Yes, you are reading that correct. The 3600lb springs were the lowest capacity I could find from the source I got everything from in a non-slipper-spring setup, which I did not want to use. I can always take a leaf out of the pack, but it's difficult to add them.

These are the same springs I had on a small 5x8 utility trailer that bounced around when empty, but was great with a small load on it.

I also think that shocks are necessary for an off road trailer setup. Many car and flatbed trailers use the vehicle's they're loaded with's suspension to dampen the load, and 99% of trailers will never be taken off road. I am not surprised at all that your springs broke on an off road trailer setup with no shocks, and it bounced all over. Difference springs rates may improve that condition, but shocks will definitely control the bounce.

My plan was to get everything installed and loaded up, take it for a drive, and adjust accordingly. More than likely, I'll remove the middle leaf.


I missed your trailer build, Riley... Just realized you had a new thread for this... Great work as always!!

I'll second the need for shocks... We have a Casita 17' Spirit Deluxe travel trailer that was manufactured WITHOUT shocks... Casita assumes that the torsion axle will be sufficient.

After a couple of years of dragging it up Roxky Mountain forest service roads, we got tired of everything bouncing, all over the trailer, and rivets breaking (it's a full fiberglass trailer).

After mounting shocked on this single axle trailer, we never have to pick up anything after 40 miles on washboard roads... And I haven't had to replace any rivets.
 
Very well thought out...i think I'd match the tailers on the truck with the reverse lights.

Very handy backing up at night.

Beautiful workmanship.

Thanks for the comment! I will definitely have reverse lights... I have 2 Rigid LED's that are the same type as the reverse lights on my 40. I am using them to light up the area while camping. The one facing backwards (toward the kitchen) will also be triggered by reverse.

Would you say it would save a lot of money to build my own trailer vs buying one with some acc already installed? I would also need to purchase all the welding equipment as well...

Really good question!

If you look here-

Expedition Campers and Trailers - Expedition Portal

You'll see all different types and prices of trailers. I think it is better to build your own if you have the time and space. It will be exactly what you want, all the way down to the color. I contemplated buying one at first, but it just didn't make sense. Nobody made one the exact size, configuration, and price I wanted. The fully upgraded Adventure Trailers are near $20k!

Some things I considered when deciding to build my own:

Wanted matching tires/wheels without running an adapter
Wanted electric brakes
Wanted it as light as possible
Wanted it no wider than my FJ40
Wanted it to be low enough to lift our black lab in without climbing the ladder
Did not want a hinged top
Wanted the tongue removable so I could park it in the garage in the same spot as my FJ40
Did not want on board battery (have front and rear power hookups on the 40 that will supply trailer power)

Those are just some of the many reasons. If I purchased any other trailer, I'd have to make those changes, so there was really no point.

As far as cost, I'm into the trailer alone about $2k, including tires, wheels, undercarriage parts, metal, latches, and lights. Of course, everything else adds up quickly, but that's just the base price.

I missed your trailer build, Riley... Just realized you had a new thread for this... Great work as always!!

I'll second the need for shocks... We have a Casita 17' Spirit Deluxe travel trailer that was manufactured WITHOUT shocks... Casita assumes that the torsion axle will be sufficient.

After a couple of years of dragging it up Roxky Mountain forest service roads, we got tired of everything bouncing, all over the trailer, and rivets breaking (it's a full fiberglass trailer).

After mounting shocked on this single axle trailer, we never have to pick up anything after 40 miles on washboard roads... And I haven't had to replace any rivets.

Thanks Danny! Will be adding shocks shortly! Trying to get it ready for Overland Expo West this weekend in Flagstaff. Probably won't have time to add them before that, but they will definitely be on before the first off road trip!
 

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