Thinking about building a 6x6

[Positrac]

I’ve been tossing around the idea of building a custom 6x6 with a high-clearance aluminum tub. I have a line on a mid-90’s MaxII that I was thinking of using for the guts, or at least the T-20 and something to follow for a frame and running gear.

I also have a line on some 2-ply low-impact tires out of Russia that I was thinking of using. They work out to about 35” in diameter and about 20” wide on 16” Rims. They make the same tires in 4-ply but that may have a bit too tuff a sidewall for a 6x6 with no suspension. I know a guy that runs tires from the same manufacturer in 51”x27”x21” wheels. Those are also in 2-ply rating and he has had no issues under a modified Jeep TJ. The 4 tires will float the TJ without the pan hitting the water.

I have means to make the tub and body out of aluminum. I was thinking a UHMW skid plate on the bottom. Space the tires on 36” centres with enough clearance on the tub to fit an Escargot style track under it down the road if needed. Those would also need to be custom built to match the profile of the tires.

I know a lot about Argos but very little about Max’s or the T-20 transmission. My biggest concern is if the T-20 could handle the torque of braking the 35” tires. I know it can handle a bit of horsepower but would it be a good option on something with big tires like this? Can parts in it be upgraded to handle the big tires or would it be the weak link?

Open to all trains of thought or suggestions as I’ve got time and want to spend as much of it as I need on the design stage. I’m a Machinist by trade so making the parts should not be an issue.

Thanks in advance for all your suggestions.

Posi

[Canadian_Zuk]

Very cool, I hope you build this as I would love to follow along. If your designing it from the ground up you could always incorporate a hydraulic disk brake setup on the driven axles for stopping and hill holding (good for shifting from FWD to REV or vise versa). The T-20 could be modified very easily with a dry sump lubrication system to keep the bands cooler and provide a larger lubricant capacity.

[allwheeldrive]

If you gear low enough the T-20 can handle anything at a low enough speed. That said 21" max II tires only weigh 7-12 pounds. What is the projected weight of these 35x20" 2 ply tires? Do you have any links to said tires. These are the kind of things that would be very nice in America and yet unavailable. I wouldn't worry about going low on the plys, 2 will be fine. People often go excess with heavy duty tires in a attempt to protect from puncture while compromising a huge amount of flotation performance.

I spend a lot of time in CAD doing volume metric analysis and I did raise an eye brow at the "TJ. The 4 tires will float the TJ without the pan hitting the water."

A single 35x20 tire on a 16" rim with zero mass of its own will only displace 536.3 pounds of water fully submerged. I do not know how much lift your friend jeep has but even if the belly pan was located 1" above the entire tire the truck would have to weigh less than 2146 pounds. 1,350 pounds less than stock, not including passengers.

[Positrac]

I spend a lot of time in CAD doing volume metric analysis and I did raise an eye brow at the "TJ. The 4 tires will float the TJ without the pan hitting the water."

Same manufacturer of the tires but the ones on the Jeep are 51”x27”x21” Rims. The pan on the Jeep actually does touch the water, just barely. He has a second vehicle, a tube-framed rock buggy that floats high enough that the pan doesn’t touch. There is about 800-1000 lbs difference between the two. Those tires with custom double bead lock wheels are about $9,500 landed in Northern Alberta. I’ve thought of going this route too but it requires a big rig and after pricing things out I would end up in the $30,000 mark all done and the size may limit it a bit on some of our over-grown Muskeg cutlines.

https://youtu.be/HYXwTnC2mmk

https://youtu.be/VBwTaiv4m48

[Positrac]

http://www.arctic-trans.ru/catalog/s...aya-900x500-16

The 35”x20”x16”rim tires are about 54 lbs each.

I’m looking at the 900x500x16” tires on the link above. The guy I know that imports from this manufacturer is in the process of getting a price for a set air freighted to Alberta.

Like I said, I’m in the designing stage and open to suggestions for design, especially where the T-20 is concerned.

[allwheeldrive]

My bad! I should have read more carefully you did say he had the 51s which would be a total of 6453 pounds of flotation fully submerged, or 3226 half submerged and what do you know, that works perfect for a TJ!

That buggy is b@d@ss! Those tires are awesome! They literally look like HUGE scaled up Deestone D930 tires. Which is funny since a lot of 6x6 drivers have those on their machines!

Have you seen my 4x4 amphibious design? It is engineered to run 35" tires exactly like you are looking at: http://www.6x6world.com/forums/other...ini-sherp.html

[Positrac]

Your Terra-Tank looks great! Those 35” tires would be awesome on there. A fully amphibious 4-wheel skid-steer the size of a Polaris Ace... Great idea. Those drawings were second to none. Great job.

I need something slightly bigger that can carry two people. I spend a fair bit of time traveling old oil and gas cut-lines and can end up dozens of miles from the closest road. These cut-lines were built during the winter when the ground was frozen. From spring to fall you can’t even get a quad or sxs down them. It’s Argos only. I’m just looking for something different than an Argo. Even an Argo up here doesn’t get you far without tracks. My worst day winching my Bigfoot was a couple dozen times. I’m looking for something with more ground clearance and full 4x4 or 6x6 drive. Hence the T-20 over a Gen 1 or 2 Argo or Admiral trans. I’ve ran the Admiral in quite a few machines and while it is better than a Gen 1 or 2 Argo trans, it still has its limitations. Plus, the motor bogging down with each turn gets tiring.

[Positrac]

https://youtu.be/7zWrQekgmdU

https://youtu.be/UR01m0uNHJI

A couple more links to videos of the rock buggy and 51’s.

[Positrac]

I could use some assistance from someone smarter than me here. I can build it, but the figuring out part is beyond me with out just doing it with trial and error.

Another possibility would be to build a machine similar to Allwheeldrive's Terra Tank, but on the 51"x27" tires. How would I go about figuring out how to gear it so that the T-20 and 30hp would be sufficient? What would the sprockets look like? I don't have a Max in front of me to gauge size of the sprockets to figure out what the equivalent would be with the 51" tires.

Any advice or assistance would be appreciated.

[thebuggyman1]

How would I go about figuring out how to gear it so that the T-20 and 30hp would be sufficient? What would the sprockets look like? I don't have a Max in front of me to gauge size of the sprockets to figure out what the equivalent would be with the 51" tires.

Any advice or assistance would be appreciated.

You have to start with tire circumference (PI x dia : 3.1416x51= 160 1/4) a stock max!! is 66 to 69 " Now figure out your target top end travel speed. A maxII can be in the area of 30mph (normal engine governed at 3600 rpm) How heavy will the body be? Gear down for power, fast is fun, but without the horsepower to push it you will be disappointed.
Too fast and things break easier and travel speed can be dangerous.

Browse through http://www.6x6world.com/forums/max-a...-tall-tub.html and
http://www.6x6world.com/forums/attex...ter-truck.html
These should give you some ideas. Shoot me a PM if you want more info.