homebuilt Subaru IRS trailer

deepmud

Adventurer
I thought I'd post up my little utility/camp trailer. I've had it 15 years. I've hauled logs out of the woods over downed trees, carried 2 3-wheelers on it and then hauled kids on the beach with the 3-wheeler pulling the trailer :D. It evolved into an "adventure trailer" about 8 years go, when I took the family from Alaska to the Washington, D.C. and back again (about 15 thousand miles).

It was cheap to build, and has been totally reliable, in spite of the abuse I've put it thru.

The most weight I've put on it was 2,300 pounds of flooring that I decided was too much. I drove about 5 miles across town and I offloaded about 1/3 of it to the SUV before hitting the highway at 65mph, and I'd say the highway load of about 1500 pounds I had left was as much as it should be expected to hold on a long trip. Considering it weighs less than 300 pounds empty ( I can easily pick it up) that's pretty good.

When I first built it, it was just the narrow, boat-shaped C-channel you can see here from underneath. I didn't put shocks on it until much later either, I could bounce on the tail like a trampoline,lol.
trailer003.jpg


I also was lucky that it bolted on with just 4 bolts - no money, no welder meant I put it together with bolts and a drill and some scrap steel I had. The only cash I had to spend was for the Valley 1 7/8" and 2" hitch - it's the only hitch I've seen that has both sizes marked on it. that was $22 and getting it welded on and some re-enforcement done to the front was $50.

When I made a top for it, I had a welder, and added the new longer wider deck. I figured it was time for fenders, and the deck would be both a fender and more space for stuff.

I built a plywood top, with side compartments for stuff that would also serve for a cooking area too.

trailer007.jpg


The usefull bit of information in all this is the 2 wheel drive Subaru axle - cheap, solid, strong, reliable, yet easy on the load you put on it. It's very smooth riding offroad.

Here's a pic of me helping out on a trail cleanup a couple years back.
This is not the proper way to load a trailer, lol.

cate_may_21_-158web.jpg


The old Subaru carcass was full of mud and rocks, and really pretty heavy. It was putting a couple hundred pounds of negative pressure on the hitch, but the little Zuk was able to haul it down a pretty rough trail.
Here's another load it hauled out the same trail.

p1010010.jpg


So, it's a pretty cheap/simple way to make your own trailer that handles just about anything you can throw it it. The 2wd Suby axle has simple roller bearings that are repackable. The odd subaru bolt pattern can be overcome by converting to 6 hole chevy/toyota/nissan pattern. This is easy cause it's the same bolt circle - I plan to make it a bit more offroad this year by doing this. I will knock out 2 of the studs, bolt on a toyota rim with the two that are left to align things and mark/drill the remaining 4 holes using the rim as a pattern. It will take some fenderwells since the subaru tires already are a close fit and some 15" tires will be quite a bit bigger.

I never used the brakes, but you could do surge-brakes using the subaru system I would guess.

One more pic, showing the deck of the flatbed. It's just over 8 feet long by about 5 feet wide. In a pinch, you could sleep inside the box I built, but you'd be cozy :D
trailer002.jpg
 
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deepmud

Adventurer
Lol, small internet after all? But no Zuk parts, so, ya' know, it never came up! :D

yeah, it's been my offroad trailer, camper, sheetrock-getter, it rocks. I've had comments from "wow, that's a really great trailer" from guys at Home Depot to "I wouldn't take that thing on the road", but that was from the Internet, lol, and he had no comment after I mentioned it's been coast to coast and up and down the Alaska highway. It has like 10" of travel, too. I've considered adding a second suby axle but I don't see the need - I have a dual axle Suzuki hauler for bigger loads.
 

deepmud

Adventurer
2300 lbs of load
trailer-loaded.jpg


really, OVERload :D but when I took a few off the top, the suspension gained 3 or 4 inches of travel and behaved itself.

Tough crowd, lol.
I've looked at every page of the expedition trailers section, read thru most of the "build" threads - there are some great ideas here. This is a good option for some of you guys looking to do a homebuilt offroad trailer. Better than some of the older leaf spring trailers for sure. Not as good as the AT suspension maybe, but very good, and dirt simple to build. It would make a SWEET offroad Teardrop - my wife is claustrophobic, or I'd have built one already. Getting the wheels matched to Jeeps or whatever might take some machine work, but it's not crazy expensive to take the drums to a machine shop to have whatever pattern you want drilled, if you couldn't do it yourself. I don't know what a junkyard would charge for that axle, but it can't be much. If a 2wd isn't available, a 4wd unit would work - you'd have to cut the cup of the CV shaft off to remove the axle but leave the spindle, but a 4" grinder is 29.99 at Home Depot, no biggie. The torsion spring isn't rubber, so it won't wear out from dirt/grit. It's soft enough sprung for really light loads, while able to absorb extreme punishment when heavily loaded. I'd guess I've had over 1500 pounds of logs on it at a time, in the woods, and the trailing arms are great for dragging it over downed trees and such. I wouldn't hesitate to haul this trailer on any trail that wasn't 2 feet of mud. It can take any trail that a street legal 4x4 can handle with about a thousand pounds of load on it, and then hit the highway at 80mph without missing a beat, you wouldn't know it was behind you. It's only drawback might be that the Subaru track-width is a bit narrow - there are some conditions where tracking in the ruts of the tow rig can help, but it's never been a problem for me.
 

Root Moose

Expedition Leader
What is the WMS on it?

Looking at it I guess there is nothing saying you couldn't splice/sleeve the center tube to make it whatever WMS you wanted?

What is the bolt pattern? I'd need to adapt to 5 on 5.5" to match my modified XJ.

I've got a set LWB SJ410 rear leafs (with the overload) I was planning on putting on my pop-up but this looks a little more advanced. Was never happy with the idea of 2" wide leaf springs anyway.
 

deepmud

Adventurer
4 on 5.5 - which is why it's great for adapting to 6 on 5.5 - not so easy for 5 on 5.5 but still do-able with some careful measuring - the single stud will still help align and center the wheel while you mark and drill 4 other holes. There adapters from 6 to 5 hole too, I believe. That might help in case of deep offset, large tires.

I think it's a single torsion bar in this suspension. The 4wd version has an adjustment bolt in the center, you can lift the back end about 2 inches from cranking down that one bolt. So - maybe - maybe it could be cut in half, and turn it into two separate assemblies. It would depend on how it is secured in the center. I know of a 2wd unit, over at my friends house (grant, logjam on pirate) - he might be into cutting it in half, just to see :D. And I'll check on the current WMS.

A thought - the older style Subaru suspension, the 79 body style, did have 2 separate assemblies. It would take more work to bolt it on, I would think. I'll see if I can find a picture of that style, and see what it would take. I seem to recall the carry capacity of an older Subaru Brat was 800 pounds - take away the body work of the car, it might be 1000 - would that be enough?
 

deepmud

Adventurer
Found this site:
http://www.subarubrat.com/

He's as nuts about his brat as I am about the Zuk :D He's got a pic of the adaptation from 4 on 5.5 to 6 on 5.5, the easy one, but the process for 5 on 5.5 wouldn't be too bad, and you can see what the trailing arms look like with 33" Swampers.

No pics yet of the older style, individual right/left suspension that I can find.
 

Root Moose

Expedition Leader
The stock bolt circle is 5.5"? That'll be trivial...

I didn't realize it was a torsion bar suspension. The lack of coils should have been a give away, ya think? :D

Do you have a ball park WMS as it sits? If it is anywhere between 55" - 62" it would be fine as is for my purposes. I could adapt to it since the plan was to tub the box/chassis to get the tires inside the edges of the trailer box anyway.
 

deepmud

Adventurer
I did a quick measure out in the snow - about 60" tire edge to tire edge - you can see about 2" back space from there to the mounting face - so 56" or so WMS. It's set up for a 2wd offset rim, so there is a lot of room from the WMS to the swing arm for bigger tires.
 

Root Moose

Expedition Leader
deepmud said:
I did a quick measure out in the snow - about 60" tire edge to tire edge - you can see about 2" back space from there to the mounting face - so 56" or so WMS. It's set up for a 2wd offset rim, so there is a lot of room from the WMS to the swing arm for bigger tires.

Cool. I'm running 16x8 w/ 5" BS so that sounds like it may work alright. I'll have to go scrounging.
 

Erich_870

New member
Deepmud,

Didn't know about this thread until just now. I'm really interested in finding out which Subaru's to look for to build something similar. We have junk car days a couple times a year and I'd love to snatch the rear suspension off a junker this summer.

How far apart are the connection points for suspension to the trailer frame?

Thanks,

Erich
 

deepmud

Adventurer
Deepmud,

Didn't know about this thread until just now. I'm really interested in finding out which Subaru's to look for to build something similar. We have junk car days a couple times a year and I'd love to snatch the rear suspension off a junker this summer.

How far apart are the connection points for suspension to the trailer frame?

Thanks,

Erich

Early/Mid-80's - Mine is from a 2wd Wagon. I think the Wagon might have a heavier torsion spring than a Sedan or Hatchback, but I'm only guessing. The 2wd uses a spindle and cone bearing pretty much like any trailer or non-powered wheel on a car. 8 or 9 years ago, I greased the bearings, noted the damaged surface and hit the highway for the lower 48, figuring I'd be replacing them by Washington state, at least, if not sooner. They are still in there.
The 4wd rear end would require cutting the birfield cup or at least pulling the half-shaft out of it - not too difficult, I think cutting the boot and popping the balls out of it would do the job. The 4wd has a single ride-height adjuster bolt on it too.

The four bolts that hold it all together are about a foot apart - I'll get some close-up pics - I did a pretty hack-job with my hacksaw to make it fit the c-channel, but it's held up to severe over-loading and abuse for years.
 

Erich_870

New member
I've been keeping my eyes peeled for junk Subaru's around. No luck yet :coffee:

Still don't have the wife on board, so I'd have to figure something out if I found one anyway. :26_34_3:

Erich
 

alfio

Adventurer
great build

thanks for posting this! i'm thinking about a trailer project and i would like to build something on a toyota pickup bed (along the lines of this example) and your idea of using the Subie rear end would make it a) easier to deal with because once i get the frame together it would all bolt together (bed to frame, suspension to frame) and b) possibly give me better ground clearance than a solid axle + leafs.

i would have to look into dimensions because i'd want something to match the axles on my truck ('92 toyota 4x4) and into bolt pattern options because i would want to run the same rims + tires as my truck.

deepmud: i couldn't find anything online detailing dimensions, do you think (with the correct rim setup) this axle could match the 58 1/2" WMS + rims of my toyota's rear axle (if that makes any sense)?

alfio
 
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deepmud

Adventurer
thanks for posting this! i'm thinking about a trailer project and i would like to build something on a toyota pickup bed (along the lines of this example) and your idea of using the Subie rear end would make it a) easier to deal with because once i get the frame together it would all bolt together (bed to frame, suspension to frame) and b) possibly give me better ground clearance than a solid axle + leafs.

i would have to look into dimensions because i'd want something to match the axles on my truck ('92 toyota 4x4) and into bolt pattern options because i would want to run the same rims + tires as my truck.

deepmud: i couldn't find anything online detailing dimensions, do you think (with the correct rim setup) this axle could match the 58 1/2" WMS + rims of my toyota's rear axle (if that makes any sense)?

alfio
back on post 9 I got a "close guess" of about 56" for rootmoose. You could run 1" spacers. 6 hole Toy/Chevy bolt pattern is dirt-simple, since the Suby happens to share the same bolt-circle diameter.

It would give you better clearance, for sure. I guess using the bed makes sense - it's very strong for it's weight, hard to beat it with homebuilt stuff, not mention the "cool matching look" :D Just try to keep total weight less than 4 or 500 unloaded so you can have decent cargo capacity.

The other option for making it wider would be to split the torsoin and re-weld it at the WMS you choose - however this raises the complexity and removes the junkyard cheap parts options.
 

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