ST2-NG Pre-build "Think Tank"

Kartorbust

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I had been contemplating on doing this for a few days now since I purchased my plans, might as well just do it. The other day I bought the Badland Buggy ST2 Next Generation plans. I had been going back and forth for at least a year now on whether I was going to draw up my own plans, wing it, or buy plans. I took the latter route, mostly because I'm terrible at drafting, especially when I have zero idea on dimensions of parts needed (seat(s), engine size, gearbox, spacing, etc).

I chose these plans for a couple reasons over others I've been looking at for a long time;
1. Full suspension
2. Single seater
3. Can use snowmobile engines more easily
4. It's a bit more narrow than other buggy plans on the market.
5. Ujoint axles and not cv axles.

However and this is where this thread comes in at, plans call for 1" keyed shaft for the axles. After seeing some modified engines rip this size axle like crazy, mostly breaking keys and stripping out the keyway in the shaft. Though the way this buggy is designed, they call for a full length key going from one end to the other between each ujoint. Though I question if this would alleviate the problem with the power being transferred through out the whole thing.

Another thing is, ujoint selection is a bit worrisome. Ones I'm finding are either the ones from Surplus Center, which are lower power rated, like 10-28hp maybe even lower in some cases. The others being from Summit Racing and other websites, these being Spicer 1000 series ujoints. However, no specs are readily available, such as maximum working angle and power rating. I have been considering using Spicer 1310 ujoints and yokes, but those have a 1 1/4" bore with the 1/4" or even 5/16" keyway. These 1310 ujoints have a maximum angle of 27⁰ to 30⁰, continous torque rating of 130ft/lbs and max continuous torque rating of 790ft/lbs.

I'm still pretty much set to use the Arctic Cat 500cc fan cooled engine I have in the Pather 5000 snowmobile. I'll be getting the dual cylinder head temperature gauge, just so I can monitor the engine while riding, especially in the summer. I should be fine long as I keep an eye on the temp and not let it get close to 600⁰F (300⁰C), maybe a bit lower to give myself more peace of mind. May do an engine rebuild, but I'm not sure. Need to first clean/rebuild the carburetor on it and make sure it even runs.

The bolt pattern they want to use on this is a 5x4.5. However wheel selection sucks when looking for tires to use. I'm looking to go with 25" tires on it to keep the overall gear ratio at 12:1 with the gearbox. More than likely going with the Polaris Trailboss 350L gearbox. Should give me the ratios I need for the reduction. Output will be a 13 tooth with a 54 tooth sprocket on the spool. So in high gear I should be going no faster than 50mph or so and low range should top out right around 20mph with the CVT in overdrive. I'm going with the suggestion of the Polaris P90 CVT instead of the Arctic Cat hex drive.

Plans also only call for a single brake. I may go with dual inboard brakes if I have the room. I'm not wanting to use an automotive brake rotor, probably have a shop cut a 9" rotor 1/4" thick and use Wilwood SC10 twin piston caliper(s) for braking. Should be plenty. Unless a single piston would give me ample braking? I rather have too much than not enough if that's even possible.

For tires, I was hoping to go with Kenda Bear Claw K299 in a 25x10x11 for the rear and 25x8x11 in the front. But with the wheel selection being limited, since the 5x4.5 lug pattern is most commonly used for trailers, it's hard to find that size. A 4on4 or 4x110 would be more common to find, since those are used on ATVs quite a lot. I'd prefer to go with steel wheels for several reasons.
1. they allow for clip on style wheel weights, which makes my job infinitely easier when I want to balance the wheel and tire vs tape/sticky weights.
2. They are a lot cheaper than aluminum wheels.
3. If I hit a obstacle and bend it, I can bend it back with a hammer vs aluminum which cracks or needs to be professionally refurbished at a cost.

I had thought about using go kart wheel hubs that are 4on4, but I question how well they would hold up with a 40-50hp engine and the amount of abuse they would take on the trails. I've also only have found either an aluminum set for 1 1/4" axles or the standard Azusa Engineering steel ones for 1" axles. But I have no idea how well they will hold up again.

On another note, I know the stator output on the engine is going to be quite low. However, the way that I'll be running the CVT to a gearbox now and not a chain jackshaft (which the plans actually has the option to make), I cannot utilize my GM Delco alternator, which would give me more than enough power to run at least 2 65w LED flood lights, brake light, and a couple backlit gauges. Will have a battery mounted somewhere on the buggy, but it won't be getting much of a charge. Plus I think I'll need a rectifier/regulator for it, since I believe this stator is A/C only.

Sorry for the long winded first post of this thread. But these are a good portion of my thoughts and thought process that I'm going through before I buy more stuff and before I start building this. I need to have a decent game plan ahead of time so I can built it without having too many issues from the start. Also another reason why I chose to buy plans and not wing it.
 

Brianator

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I'm sure the lighting is the least of your worries but is something I can help with, I've run a LED conversion off a stator with success by using a diode rectifier and a 2200mF capacitor for each light (it helps with the inherent flickering).

Here is a website I had saved that helped steer me in the right direction and a photo of a full wave diode rectifier (on the left - including the part number), a similar 600 volt unit will work just as well. This is by far the cheapest and easiest way to go but it's dependent on your stators AC output and the demands you wish to place on it.

https://www.snowblowerforum.com/threads/upgrading-your-snowblower-lights-to-led-lights.6602/

If you want to get more advanced and use a small battery to power the lights it's not hard to build a charging system using a rectifier/regulator like this John Deere (Kawasaki engine) unit and they can be found for about $40 (pictured on the right). That would also give you the ability to turn the charging system on/off if you wanted to by using a SPST toggle switch on the "excite" wire. You'll want to measure stator AC output first to verify it will provide enough juice to work.

I agree ATV wheels are the way to go, they're not only designed to handle the power and abuse but there's a great selection of wheels and tires!
 

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Kartorbust

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Something to think about for sure. The lighting is further down the list, but was what popped into my mind while writing the long winded post.
 
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Kartorbust

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I guess we can start from the top with my main concern, 1" axles and ujoints. Plans call to use both and also call to use key stock the whole length and not cut them to a few inches. After seeing modified engines shred up axles left and right more than likely from not having that much key stock, I still have a concern with the problem arising on this. The other part is the ujoint selection. As stated above, at least from Surplus Center, 1" bored keyed ujoints are rated somewhere around 10-28hp (maybe lower depending), I'm probably close to double the horsepower and if I had to swap in an engine later, it'll probably be an even higher chance of them breaking off. Only Spicer 1000 series that I can find meet the 1" bore and keyed part, but the power rating and working angle is not known. Cannot find any documentation on it. However Spicer 1310 ujoints are known, but those start at 1 1/4" keyed with either the 1/4" or 5/16" key way.

So will full length key stock alleviate problems and would I be better off going with a larger ujoint and axle for parts selection and possibly more strength for higher power engine choices for the future?

*Edit*

Just purchased the gearbox that I will be using on this (hopefully it work). It's the gearbox from a 1990-93 Polaris Trail Boss 350L 4x4, manufacturer part number according to the ebay ad is 1341080 8477. Should work well. If the gearing is where I think it's at, should just need a 13 tooth on the output and a 52 on the spool and my gearing will be where I need it to be at to make it overall useable and not worry about excessive belt wear. With overdrive, people recommend to be around 10-12:1. Once I figure out what rpm this engine runs at, I can figure top speed. Top speed in high, I want to be no faster than 50mph. Low I think will be at around 20mph or so.
 

Kartorbust

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Anyone have any thoughts on 1" axle strength being sufficient with full length keys? It doesn't seem to be that common of something people do, they just cut the bare minimal needed.
 

mckutzy

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Honestly, they build machines and other things with keyed shaft so why not, I have one on my bike.... In the end it depends on what you plan on doing with it, and how its designed...
 

Kartorbust

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Best way to describe my overall goal is a trail rider and something to overall just have fun with. Not going to be a racing buggy, but it will be something to beat on and something to modify to make better too over time. The usual.

I'm just wondering if I should go with a larger diameter keyed shaft or if I should just go with the standard 1" and look for the ujoints as well that will hold up. The engine is somewhere in the ballpark of 40-60hp and I rather not destroy anything on the axle fast after a few minutes of riding.
 

mckutzy

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Well... Like most things of this nature... Keep support bearings close as possible to the wheel and drive sprocket.
1" shaft is common, therefore some places might have it cheaper if it gets bent or otherwise damaged...
 

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I'm just wondering if I should go with a larger diameter keyed shaft or if I should just go with the standard 1" and look for the ujoints as well that will hold up. The engine is somewhere in the ballpark of 40-60hp and I rather not destroy anything on the axle fast after a few minutes of riding.

You can't really go wrong with the extra strength of a 1-1/4" shaft and those can also be had fully keyed and found without too much difficulty. Bearings, hubs, sprockets and collars are all pretty easy to get for one.
 

Kartorbust

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You can't really go wrong with the extra strength of a 1-1/4" shaft and those can also be had fully keyed and found without too much difficulty. Bearings, hubs, sprockets and collars are all pretty easy to get for one.

That is all true. I'm not a huge fan of weld-a-hub options and I'm not going to use the #50 sprockets, going to just go straight to #520 ATV/Motorcycle chain and sprockets. Locating a 52 or 54 tooth steel sprocket is challenging but I have seen them. Then need to find a sprocket hub that will bolt up to it. I'm going to have at least one, maybe two brake rotors cut for me that are 1/4" thick and 9" diameter so I can run the Wilwood caliper(s). Unless I can figure out an easy solution for front brakes, either a single or dual inboard rear brakes are what I'm going to run permanently.

My gearbox came in today! So high range seems to be about a 3.5:1 and low range appears to be 6:1 roughly. However I am completely lost on where reverse is, I'm not sure which shaft is for the CVT driven (I have my guesses but unsure). One shaft has a gouge in it. It has been completely drained of gear oil.

The name plate sticker is hard to read but here's the best

Model number is possibly M25P1 or M25R1
Another set below that says possibly 930496552

It's for a Polaris Trail Boss 350L 4x4 four wheeler.

I'm not entirely sure what the mounting points are on it. The case bolts have no witness marks on them, only the oil fill(?) has them.
 

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Kartorbust

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Did some digging around today and found that Northern Tool has a trailer hub set for 4on4 bolt pattern. That does open up more options in my opinion since I can find more wheel options in the 10" to 12" diameter that will fit ATV tires much easier. Now just need to find the appropriate rear hubs that will work. Rather do off the shelf than fabricating and modifying automotive parts for this. Reasoning as you could imagine is, parts availability vs having to keep rebuilding something if it were to break. Rather just order up bolt it down and go.

I wonder how well these would hold up to the abuse? 1" hubs with the 3/4" step down for a nut at the end. https://www.gopowersports.com/live-axle-hub-4x4-pair/
 

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I'd like some thoughts on this. Plans call for using tubing or pipe really for the A-arms, using bushings made from either polyurethane or another material, then having a solid rod go through the a-arms and have it either threaded with nylon lock nuts or using cotter pins. Instead I was maybe thinking using chromoly 1/2"x20 threaded heim joints instead. I have 2 sets already, would need several more sets of 4 for the front and rear.
 

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Getting the VW buggy and spare parts really put a spanner wrench to this project. I know at this point I'm going to end up having two ground up builds. Leaning more towards the VW being more street with light off road and this being strictly off road for obvious reasons.

When I went up to Minnesota last month to get the dune buggy, I did get a chance to look at the sled, not long enough to do anything with it. Belt is in okay shape, but I'm inclined to switch out the CVT for a Polaris setup. Kind of on the fence with the FNR gearbox since it only goes in high, low, and neutral, not reverse. Maybe it'll be easier when its hooked up, I'm not entirely sure.

Both project vehicles are going to be very slow, looking into a larger welder (power wise) for these projects. Also have to look at getting a house with a garage to build and store these. Hopefully nothing drastically changes over the course of these builds, such as needing to convert to full electric because of reasons (not out of the question, but not looking forward to the headaches associated with it).

Just giving a small update on this, nothing is set in stone. Really do not want this to be shelved indefinitely.
 

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Is there a way to figure out wheel travel by going off of the plans and not having anything physically built? Trying to price out shocks since the ones they reccomend are either hard to come by or are not an exact fit. So looking at Fox and FOA. Plans call for an eye to eye distance of 11 3/4" for the front and 16 3/4" in the rear. However that doesn't tell me wheel travel.
 

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So after searching for shocks for the proper eye to eye length from AFCO, FOA, Fox Racing, and random Chinese Buggy shocks as per the buggy plans, I've found that it'll be easier to make this as a Next Generation and Long Travel chimera (hybrid). The difference between the ST2-LT and the ST2-NG is mainly shock placement. Front shocks on the LT are mounted externally via shock hoops mounted. Whereas the NG are mounted internally on the roll cage.

So to help with my predicament, I've decided at least for the front mounts, do them as long travel, with the shock hoop mounted externally and run a more common shock. Looking at Fox Racing 2.0 air shocks front and rear. Just have to figure out what the travel of the front and rear so I know what shocks to order. For the rear, I may mount those similarly to the current ST2-NG plans, but may do them a bit higher.
 

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Found a photocopied of the Arctic Cat Panther Hex clutch. It's not a full manual, seems like only a few pages were copied and turned into a PDF. Belt width is 1 1/4" and a worn belt measures at or less than 1 1/16" wide. Low end is 3.79:1 and top end is around .94:1 to 1.05:1, manual wasn't very specific. Did a bit of searching for clutch replacements and only finding the primary and no secondary. I've been searching for Polaris P90 and P85 drivers and the respected driven, but only found the driver. Main reason is that I want to use the gearbox I got this past summer. Being that it's from a '93 Trail Boss 350L 4x4 squad, I need the proper clutches.

The gearing on this is getting interesting. Still looking for the RPM range of the Suzuki Spirit in my Panther. With it being a stripped down version of the Pantera, it may have a 6500rpm rev limiter possibly. Horsepower difference is 50hp on the single carb Panther and a bit north of 60hp on the dual carb Pantera. Seems like there might be more to those numbers than just carb setup, such as CDI, flywheel, and Stator.
 

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I've been talking with people in the mini buggy world a bit with this and it's making me really over think this whole thing. Basically what it boils down to, they recommend that instead of using the gearbox I got, that I find a snowmobile chaincase that has mechanical reverse built in. Reasoning behind this is because the chaincase is right around 2:1 gear reduction and I would not have to run a large rear sprocket, I could go with a 45 tooth instead of a much larger one.

Their reasoning behind this is, with the Trail Boss gearbox high range is only 1:1, I would need another reduction after the gearbox to the rear axle to get the 8:1 or lower gear ratio they recommend when using a snowmobile engine. If I could find out if I could run the gearbox in low range constantly without long term damage, I could use the gearbox 3.5:1 low range no problem for reduction. At that point I also need to figure out how lock the sprocket onto the gearbox. At the moment, it just slides on the output shaft and I'm not sure if there's supposed to be a locking collar of some type.

Almost seems like I should just ditch the gearbox and not even have reverse just to avoid issues. The jackshaft in the plans would allow for more gear flexibility. Could maybe even run hubs with a split sprocket to make swapping them out easier. Though it does not show any way to adjust chain tension. Another thing is, the center to center distance they call for from the jackshaft to the axle is 13 1/16", seems kind of short?
 

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Finding the proper ATV clutches to work with the gearbox hasn't been a challenge, but finding them in a decent condition and not beaten to hell, not an easy task. So I may hold off on using the gearbox for a while. On the upside, I did find a set that will work, 102C and a 90D. Gives a 3.28:1 low with a 0.78:1 over drive. So this maybe a temporary to permanent choice for this build.
 

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So on my previous trip to Minnesota for my time off from work, to possibly to work on the snowmobile (didn't happen unfortunately), got a better look under the hood. Turns out, the engine does not have an expansion chamber exhaust. Just a 2 into 1 flange into a large muffler. Unless this is an oddball expansion chamber (could be), for now I'll assume the engine does not have one.

So with that being said, would it be more beneficial to have a customer expansion chamber built (professionally built, this type of work is beyond my knowledge base. I know of books and what not, but I lack the skill set) or should I just do traditional exhaust, modified compared to the current stock version, since the muffler is pointed forwards and would be in the way of the gearbox or jackshaft.
 
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