2006 Argo Avenger with T20

[Mike]

I wanted to post up some of the spreadsheets I've been using while trying to determine what gear ratio I want to use. In trying to keep things simple and do as little work as possible, I am trying to only change the sprocket on the Argo's intermediate shaft to get the gear ratio that I want. I recently opened up my Argo transmission and calculated it's gear ratio by counting teeth. Here is a summary of the stock Avenger transmission gear ratios that came in my Avenger:



I took that information along with a tooth count on both my Max IV and the Avenger drivetrain to help me determine what tooth count I needed on the intermediate shaft sprocket to mimic the gearing in my Max IV. I have also included the low and high gear of the Avenger transmission with the stock Kohler motor just for comparison since I already had this information.

I am probably going to go with either a 15 tooth or 17 tooth intermediate shaft sprocket. Here are the two spreadsheets showing the difference in gearing and speed between the two. The orange highlighting represents the sprocket that I am going to be changing:

15 tooth sprocket on intermediate shaft:


17 tooth sprocket on intermediate shaft:


Any thoughts on gearing? I could have made a mistake in my calculations somewhere as well. I put these together pretty quickly to keep me from doing these calculations by hand so let me know if something doesn't look right.

[Mike]

Thanks for the input. I think I can get it to work with the linkage under the T20. I want to get a mount mocked up and tacked into place and then start moving forward with some of those decisions.

Here's where I currently stand with the engine mount. I began by taking some measurements and sketching what I wanted. I used the stock motor mount as an initial starting point. Then I drew that in CAD. From there I printed it out on paper and used that as a template by cutting it out and actually putting it in the machine. I have done several iterations of this process making slight adjustments as I go. There are so many pieces to this motor mount that I wanted to get it as close as possible on paper first to save me from having to cut metal more than once. I'm sure there are things that I will still have to modify but I have already found many things that needed to be adjusted so I think it has saved me some work already.

Here is the mount I have currently in CAD:


Here is the original Argo mount next to the paper template that I am working with:


Testing the template hole locations in the Argo frame and on the T20 itself:


Finally, here is the T20 just sitting in the Argo in the approximate location it needs to be:

[thebuggyman1]

I'm with Mark....split the shifter. You really won't use it much, at least on dry land, but in the water it is fantastic. As far as the added stress of the 8 wheels, the Avenger only has 6 touching, the bands will just slip if it does take too much, and there are tricks to making counter rotation easier. Mark had his fancy sophisticated terms like "static and sliding".....What I know from playing with it, scratching my head, and playing some more is: It IS tough to counter rotate from a standing stop...I'm guessing it is from trying to slide 2 tires each side sideways (4 tires) at the same instant. But if you start moving (just creeping) counter rotation is much easier. Where you really notice the difference is on hard gravel or concrete. Loose/soft dirt or mud counter rotation is easy. And that is with a 16 hp briggs in the tan MaxII I have. With the bigfoot (40 hp) it doesn't matter.
Going over the top of the t-20 with the linkage would work, but would make the sticks backwards....unless you built a simple bracket with a pivot. You could even bolt that to the top of the t-20.

Mike: Dibs on the Kohler if you decide to sell it
I wish I was closer...I'd come over and volunteer some labor.

[MAX IV Mark]

Just to share my thoughts (right or wrong as they may be)

I have the opposite opinion on the split shift, I think it would be benificial. On my bobcat skid loader you can hear the motor load on turning, being constant throttle hydrostatic machine. If you try to keep one side of wheels stopped and try to turn with only the other side moving, it takes a lot of power as it tries to drag those two stationary tires sideways(yes, only 4 wheels on it). But, If you turn one side forward and the otherside backward, the motor does not have to work as hard to turn the machine. This is somewhat similar (but not exact) to the concept of sliding friction versus static friction.

And since you want to keep the T-20 as low as possible, what is keeping you from flipping the U channels over and running the steering linkage over the top of the transmission?

MAX IV Mark

[mightymaxIV]

Wow, man you have a lot of work in front of you. I would leave the split shifter option alone. It takes to much power on a 6x6 and I believe it would over load the T-20 on an 8x8 with ASX tires.

I would consider a built 23 horse briggs, but as you stated cooling will be an issue, if you can get it to fit the fuel injected Kohler is a very nice engine. If you decide to go for a for a briggs it be intersting to see a hot rod 8x8 Argo with a 5 or six thousand RPM red line. I would like to see the look of the 4x4's when they see and hear that Argo coming a half a mile away.

It will be worth a trip to Busco just to see that machine eat mud!

[Mike]

I thought I would revive this thread and document the next stage of the build. It's been over a year since I initially purchased the Avenger. It took me several months to get it ready for a ride at Busco Beach last April and in doing so, I choose to keep the stock engine and transmission to save time on the build. On its shakedown run in March or April before the Busco ride that I was rushing to get ready, several things went wrong. While on the trails, the spring clip that holds the high gear on the transmission input shaft slid out of its groove and allowed some teeth to get eaten up. Then while limping back to the trailer, one of the brakes quit working and without steering, I was unable to stop from plowing into a tree. I didn't have enough time to get it fixed before the Busco Beach ride so I just parked it and didn't touch it for another several months as my work schedule got busy again.

Now I finally have some free time to start working on it again and I decided to upgrade the motor and hopefully put a T20 in it. I'm in no hurry this time and plan to take the build slow but I would like to finish it in time for next April's Busco Beach ride. If not, it's no big deal but that's the goal for now. So here are the things on the to-do list:

- Build a motor and transmission mount. I am going to copy the stock Avenger powerpack mount as closely as I can so that I can use the existing bolts and frame holes to hopefully save some work. This will also save me from having to build any chain tensioners for the T20 as the chains will be tightened by raising the entire T20 just like you do on the stock Avenger transmission. I have the mount design close to completion. I have designed it in CAD and printed off paper templates. Then I revise and repeat. I wanted to have the T20 output shafts directly over the intermediate shafts in the Avenger but in order to get the T20 all the way behind the stock firewall I will have to have it about 3/4" in front of the intermediate shafts. That should still allow proper chain adjustment.

- Decide on a motor. I'm leaning towards another Bandolero motor but have concerns since it's air cooled and I will have to build some ducting on the intake and exhaust. If I go with a motor other than that, I will need something with similar or greater torque and high RPM to make up for the single speed transmission. I'm not against building up the water cooled Kohler that came with the Avenger but I think having to relocate it will require me to relocate the radiator as well and then I would have to add an electric fan, better charging system, etc. I'm going to wait until I get the T20 located to see how much room I have and decide from there.

- Decide on the gearing. I have loved the gearing on my mid-engine Max IV so I am going to target that same gear ratio for the Avenger. It matches very well with the Bandolero motor torque curve and should have plenty of low end torque.

- Extend the splines on the intermediate shafts. The T20 is wider than the Avenger transmission so I will be extending the splines on the intermediate shafts to allow me to move those gears further outboard.

- Remove the Avenger steering. I initially wanted to keep the handlebar steering and make it work with the T20 but I have concerns of not having the T20 fully engaged while in forward.

- Build laterals and linkage. I have worked on the motor mount enough that I think I have the room I need under it to run the shifting rods. I have kept the T20 as low as I possibly can and plan on either extending the c-channels on the T20 down to meet up with the shift linkage or building some bends into the shift linkage itself. I haven't gotten that far yet and want to get the motor mount built first.

- Build the F-N-R shifter and linkage. I'm undecided on how I want to approach this. The T20 is right in front of the firewall so I could do something as simple as two handles sticking out of the firewall that you push forward or pull backwards. But I will probably end up with something a little more rigid. I am leaning towards a split shifter but have concerns about the torque on the T20 with a counter-rotating 8 wheeler.

- Modify the firewall and floorboard or build new ones. The plastic firewall will not work with the T20 as the recessed foot rests stick into the engine compartment too far. They will hit the secondary CVT. So I will either have to remold it with the heat gun or just build on out of aluminum. The floorboard will not work either as it sits all the way on the bottom of the frame plate where the laterals will have to be mounted. I'm not even worried about these until I get it running.

That's enough of a memory dump for now. I will try to keep this thread updated from here on out as I go so it's not so much information at once. I have some photos I can share later as well.

[Rock Doctor]

Speechless

Love it

RD

[MikeyM]

WOW! That thing looks tough!!!! Good job! One of these years I need to take on the drive and get out to busco, from the videos ive seen, it looks like an awesome time!

[Mike]

Taking it to Busco?

Yeah, my wife will be driving it there.

[rickga]

Nice machine mike! Like the tires too. Taking it to Busco?

[foxvalley]

Congrats Mike! Looks like one sweet ride.

[Mike]

It only took me 5 1/2 months but it is finally ready to be tested out. Mud flaps were the final task on my to-do list and I finished those up earlier this week. A lack of free time really drug this build out but at least it will be ready for Busco in a few weeks.

Here it is from two weeks ago when Jennifer first got to drive it:


Here it is with the mud flaps on it:


While I had it apart, I was debating on whether or not to throw a T20 in it but I knew if I did that, that it wouldn't be ready in time for Busco. racerone3 let me borrow his spare though so I could test whether or not it was even feasible while I had everything torn apart. You can read my thoughts in the gallery under these photos:

[lewis]

Yes, that is quiet an attractive machine you have there!

[glen1971]

Nice looking machine!!

[Mike]

nice!....is it going to busco?

No, it needs some chain before I take it out for some serious riding.

From where I sit I would say it is time to break out the drill and make this into a key fob.

That's a good idea.


Thanks for the comments everyone.