This is a build I've been planning and scheming for years, beginning sometime when I was in high school building a full-suspension off road go kart, or when I was in college working on the CSM Formula SAE car. After off roading a couple Subarus, and a big dumb diesel F-350, what I really wanted was a side-by-side UTV. But I can't afford and/or can't stomach a pricetag between $15k and $25k for an offroad-only toy that also somehow breaks fragile expensive special atv parts all the time.
I've been through hundreds of hypothetical builds, with lots of sketches, Solidworks models, lots of mental gymnastics, and even an aborted year long detour with half an upside-down Subaru Legacy occupying my garage for a suspension jig for an AWD Subaru based buggy that never happened. I've been hoarding parts for so long and over so many idea iterations that I've lost or thrown out parts that I actually need now :(
I decided now was the time to start building _something_, using as many parts as I already have lying around, and get the project rolling. We have a trip to Moab planned for my wife's birthday in 2021, and a 10 month old baby who I want to eventually show all the great outdoor destinations we have in Colorado. So this as good a time as any to get started.
The outline of this build:
- ~1000cc engine, manual transmission, transfer case with 4x2/4x4 high/4x4 low capabilites
- Independent suspension at all four corners, 30 to 32 inch tires, medium wheel travel
- Use as many automotive parts as possible, for maximum strength, junkyard scavenging potential, and cheap replacement parts
- About 84" wheelbase (dictated by driveshafts I already have), and 65" width (max that fits on my trailer)
- Relatively lightweight, stiff tube chassis using a lot of Locost frame concepts; curb weight of less than 1500 pounds for easy towing with my Grand Caravan.
Progress started with a build platform, sort of a legless table, constructed from 2x6s and a 3/4" MDF skin. I'm currently working out of a two car garage at a rental house while we build our new home, and this garage already has two cars in it, so I had to figure out how to work around or even under the other cars.
Then I started laying out parts from my shed full of garbage. Subaru R160 rear differentials, Subaru axles and spindles, a Suzuki Samurai transfer case, and driveshafts left over from a scrapped lifted Legacy project.
Tiny baby and I took a morning trip to Tube Services today to pick up 80 feet of 1"x1"x.065" and 60 feet of 1.25"x1.25"x.065 square. Some layout with pencil and straightedge on the table, and some band saw work, and we go from 2d to 3d in the space of a couple hours.
The chassis will consist of a central tunnel that carries the differentials, engine/trans, transfer case, and suspension pick-up points, side pods for passenger seating and storage/accessory mounting, and a roll cage built to fit after the rolling chassis is complete with seats mounted. Lots of triangulation and trussing will happen in the chassis before it's finished.
I decided to screw the lower tubes directly to the table to hold everything tight. These holes will later become vent holes for welding the chassis, or get plugged with a dab of TIG.
Beginning the first of many hundred tabs and brackets with differential end mounting plates.
And the tight working quarters in this garage mean the chassis-under-construction and build table have to sleep spooning with the Starlet, or the garage door won't close.
I like this very very much so far.
The engine of choice will be a Suzuki G10 three cylinder, from a Geo Metro. I bought this at a junkyard 4th of July 50% off sale for a different project, but this is now first in line. I can always grab another or two for $100 later.
This engine should be somewhere around 100 lbs fully dressed; in it's partially assembled state I can tote it around the garage by myself.
Once I got the beginnings of the frame tacked together, I had to throw the engine in to see how it's going to fit:
The oil pan may need slight remodeling for diff clearance, depending on adjustments up and down or fore-aft to tune the intermediate driveshaft length between the trans and transfer case. But the position looks quite good already.
This is going to be another one of those threads that makes me feel lame for stressing about swapping an engine that requires some minor fabrication to fit in my own 4x4 project. Then I see people with real fabbing skills :)
I wouldn't say real fabrication skills, so much as lots of tough lessons from aborted hack-job previous projects and hooptie-ass builds. A good example is the Legacy that donated parts to the hoard that is now supplying this project. Looked impressive from afar, but the fabrication and assembly was a level of hack-jobbery that I'm ashamed of today. Luckily I'm not a broke student working in the street anymore haha
I get the feeling that your hack-job would surpass my best work.
As a many-times Samurai builder, I'm wondering if you're planning to do the ~4.16:1 transfer case gears at some point?
This is awesome, I've been day-dreaming about a sort of off-road go cart with real suspension a lot lately. Looking forward to following along with this!
I will be following this with interest. Keep up the good work.
I worked for an elderly man about 15 years ago and he showed me his project which was an amphibious 4x4. He lived above the Fraser River and built it to take a little goat track down to the river and float it across. I declined to cross the river in full flood with it but he has no concerns and did it all the time. I always wonder what happened to it.
Anyway good luck with the project.
Very cool. I'm in to follow.
Yep, looking forward to seeing this progress!
I had a similiar idea with cutting up an SAE Baja car and putting a snowmobile powerplant in the rear but the effort seemed too great. this looks exciting!
I need to do something like this with a completely flipped Subaru drivetrain.
I like this. This will be neat.
You have read my mind. Please tell me it'll be long travel for high speed and sweet jumps in the woods. .....
I have a question you can help me with on my project. Your using Subaru rear axles are all 4 corners it looks like. Are you using Subaru Front uprights in the front or 4 rears? I'm trying to figure out if the hub end of the halfshaft is the same front to rear on Subarus. I want to use front halfshats in rear uprights but if your using rears halfshats in front uprights it's the same theory.
This is awesome. I've always thought an off-road locost would be a cool project.
Thanks everyone. Hopefully this won't be a long drawn out build, I have to slowly gather major parts as budget allows but I'm trying to get little jobs done here and there every day.
JesseWolfe said:
I need to do something like this with a completely flipped Subaru drivetrain.
This was one of my other plans; a Subaru 5 speed with Subarugears reversed R&P mounted in the rear like a VW sandrail, with the R160 in the front. My only reservations were the price of the ring and pinion, the lack of a locking 4wd transfer case, and the lack of 4x4 low range. The trails I like to explore range from dirt fire roads to fairly rocky mining trails and forest service roads, so I need a selectable low range more than I need high speed performance.
Dusterbd13-michael said:
You have read my mind. Please tell me it'll be long travel for high speed and sweet jumps in the woods. .....
Travel is going to be limited by the stock Subaru plunging inner CV joints, and by the shocks I'll be using. I scored four Fox 2.0 air shocks on ebay a while back for $200, they're some sort of military surplus and have 6.5" of shaft travel. I think by playing with motion ratio between the control arm geometry and shock mount position, I should get somewhere between 10 and 12 inches of wheel travel while also keeping the CVs happy.
I think a better comparison for this machine would be a sport/utility crossover SxS like the Yamaha Wolverine, Honda Pioneer, or Polaris General; a little more geared towards cruising and going camping rather than a superfast pure sport machine like a Maverick or RZR XP Turbo.
nocones said:
I have a question you can help me with on my project. Your using Subaru rear axles are all 4 corners it looks like. Are you using Subaru Front uprights in the front or 4 rears? I'm trying to figure out if the hub end of the halfshaft is the same front to rear on Subarus. I want to use front halfshats in rear uprights but if your using rears halfshats in front uprights it's the same theory.
I'm using front and rear uprights for a first gen Legacy in their original positions. The hub end of the axles is different; fronts are larger diameter and higher spline count than rears. The R160 differentials I'm using are from first gen Legacy or Loyale, so they have male 23 spline stubs. This fits the stock Legacy rear axles for the rear, and in the front I'm using axles specific to '92-'96 FWD 5 speed Impreza, as these have the same outers as an AWD axle but have 23 spline inners that fit the R160 diff. Not sure if any of this applies to your needs. Later model Legacy, Outback, and Forester started to use bolt-on unit wheel bearing hub assemblies, these might be more useful for a custom application.
1. Awesome build.
2. G-10!
3. Starlet!
4. This is meant as a constructive question, not nit-picking: Is the transfer case going to oil OK turned on its side like that? Is it from a Samurai? I like the two R-160s bit. Clean and available. I have seen buggies done like this with FWD drivetrains turned to be longitudinal and what was the driver axle driving one axle, and the passenger the other. I like your solution much better.
Carry on.
I think the transfer case should be OK; it was clocked nearly vertical in the last project I used it in also. Since it's all gear driven I think the gears should get oil where it needs to be in this application. A guy on a UK buggy forum used a Samurai transfer case like this, clocked vertically in a bike engined 4x4 buggy; I didn't see any issues reported there.
The fwd transaxle instead of a standard trans and transfer case was yet another option I pursued, but ultimately the lack of high range for travel speed and no way to unlock the front axle for traveling on hard surfaces was the downer.
Previously I had reservations about using the Subaru R160 diffs at both ends, even though I had all the parts available - mainly because there was no locking differential option available, just factory options for worn-out clutch type LSDs and hard to find torsen/suretrac diffs. But while I wasn't paying attention to the off road Subaru scene for a while, the market finally supplied a mechanical lunchbox locker. Not as cheap as for a Jeep or Suzuki, but still very affordable.
https://www.torqmasters.com/torq_locker_tl_r1605b_subaru_r160_five_bolt
I may go with one at each end, or one in the front with a welded rear.
on an off road only vehicle I would just use welded front and rears.
Awesome! This use of Subaru rear diffs and a Suzuki transfer case gives me bad ideas for an AWD autocross Locost!
