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Discussion Starter #1
I'm doing my CJ-7 Build/mod and I am going to build a trailer for it as well. Here is my plan/goal with this trailer and I am trying to source some parts and ideas on this so I want what other people think of this.

I'm running 8 lug on my Jeep, Truck as well as my best friend(wheeling partner) and my uncles rig(Check out my posts in other forums about Wagonstein). I want to have the trailer running 8 lug as well so that if worst comes to worst I can steal the spare and then even a tire from the trailer to get a rig out. The trailer will run the same size tires as our vehicles. We are running 35"-37". It will always match the size for whatever my CJ is running because this build is to be my trailer for the jeep. I have MIG/TIG/ARCH welders as well as torch and plasma cutter. I'm not wanting to be ultra radical but I have things I want.

Frame wise I am leaning toowards just building basically a tube frame for it instead of using a truck frame. I do have a truck frame but my Buddy might need it. It is a 1979 J20(Donor truck on builds).

Axle and suspension wise I want to run an 8 lug but I want to have as much clearance as possible as well as not breaking the bank. Can i just go get a 12-bolt off a 3/4 ton chevy and shave the diff and well it up even or near the axle tubes? Now I know that doing that means I would have to mount the tongue with an inertia brake on the tongue. I would much much MUCH rather have electric brakes so i can manipulate them from the tow vehicle but unless I go with a trailer axle I don't know how to do that.
Suspension I am thinking of using the rear springs off of the J20 so that I can really load the trailer and not have is sagging. I know that reduces the flex the trailer has but i will not be loading it top heavy but it will be loaded heavy especially during hunting season and camping trips.

Body of trailer I would like to use the J20 bed because you don't see them around. It has JEEP in giant bold letter across the back and I like it. I will have either an above rail tool box or a between the rails tool box with locks mounted, spare tire rack on one side rail and probably a side box on the other side. It will primarily be used for packing extra water, fuel and gear that will not fit in the CJ on trips. For hunting it will be behind my 1-ton truck and hauling all the water, fuel and any extra gear for hunt camp and we don't have a light camp, takes 4 trucks and trailers to get it all up in one trip. I will get some posts of it up this coming season.

I would like to get a between frame mounted fuel tank/cell with an electric pump for emergency fuel if needed. Main things are that I don't know how to get electric brakes without going with a trailer axle but that sets me back a ways and I am trying to build this out of parts and peices I have.
 

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A few thoughts on trailer design.
  1. Gross trailer weight + cargo + fuel + fat chicks should be no more than 80% the weight rating of the axle - personal rule of thumb. Forces me to build stronger trailers than what I'm hauling.
  2. 10-15% of your total trailer weight should be on the tow rig's hitch (3000lb trailer * 10% = 300lbs tongue weight)
  3. Strength of a trailer frame initially comes from how tall your I-beam or C-channel is, with consideration to the material thickness. Better to have a 2" C-channel or I-beam than a 2x2" .120 wall square tube. The trailer's rigidity will come from how you make your crossmembers and what portions you box in/use tube.
  4. A-frame designs are usually stronger designs than monobeams
  5. Most states require trailer brakes on at least 1 axle for trailers rated for over 3000lbs...yours might be over that, especially when full of fuel, camping gear, fire wood, ect.
  6. Rule of thumb axle placement should be at a 60/40 split plus or minus a few inches. If you have a 10ft long trailer overall, put the axle 6ft back. This helps to ensure you have enough tongue weight.

With that said, I just got done building what you're basically aiming for.. a trailer you can tow behind your Jeep with ground clearance to handle the same trails. Your 12 bolt has a GAWR of 3750lbs give or take, so add up the weight of your trailer frame, fuel & tank, supplies, leaf springs, battery?, and everything else and you might be able to have a 2000lb haul trailer. I used two sets of leaf springs from a late 90's Tahoe. 54" long, centered pin and they're relatively cheap. I used two main leafs, two #2's, two #3's and did not use the overload. So far I've hauled a 3/4 cord of wood four times with it, two heavy motorcycles once, a set of 1-ton axles once and $1500 dollars worth of roll cage tubing twice. So far I can't complain. If you're going to use the J20 springs, plan on slipping another leaf in to support the main leaf. You'll lose inches of tire clearance within the first 200lbs. Stiffen up the main leaf somehow.

For materials I used 2x3" .250 wall for my draw bar, braced with 3" C-channel to the leaf spring mounts in an A-frame fashion. The rest of the trailer is 2.5" angle iron .188 wall with 1.5" .125 wall angle iron railings. If you use 3" or 4" C-channel for the frame rails you could probably mount the J20 box easily in a factory fashion.

Shocks I used S10 4wd front shocks. They're short, but have plenty of dampening pressure for when I'm loaded down. Cheap too.

If you don't want trailer brakes, keep the weight down. Keep in mind a typical cord of wood weighs 2500-3500lbs depending on species and how dry it is. Weight adds up fast.

Put more tie down points than you think you'll need. You'll end up using every one of them. I have them spaced every 2ft, with additional tie down points up front and in the corners.

I don't want to clog up your thread with unwanted pictures, so PM me if you want to see what I built.
 

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Built the trailer with as many parts that fit your jeep as you can.
You never know when you need to steal an axle from a trailer.
 

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A 6k or 7k torsion style trailer axle would give you plenty of capacity, electric brakes and 8 lugs along with great clearance if ordered with the torsion arms rotated down.
 

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Discussion Starter #5
A 6k or 7k torsion style trailer axle would give you plenty of capacity, electric brakes and 8 lugs along with great clearance if ordered with the torsion arms rotated down.
What would something like that run and can I just order that from any trailer supply place?
 

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Discussion Starter #7
Rear sprigs I also have the 1-ton chevy rear springs with helper springs. It was used as a farm haul/tow truck by my grandpa so I know it doesn't squat much at all when you load it. They are brutally stuff though so I was worrying about using them that it would not have any flex and possibly cause it to tip.
 

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With a torsion axle recommended you don't use springs. That's the "torsion" part of it.
 
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