First Build

[Bdog]

Hey guys. Been trolling this forum for about a week now for ideas and such. My wife of all people has said she'd like a two seater for us to bomb around on, so I'm running with it before she changes her mind.
I found a running Honda Fourtrax 300 at a local scrap yard, just missing the wheels/tires for $100, so that's my donor bike.
I'm thinking an offroad buggy style build, and since I have virtually NO skills for this, I've recruited a friend of mine to help. He's done all of this before multiple times, so I am in good hands.
We were originally going to use an old free-air snowmobile engine, but have scrapped that in favor of the Honda. I'm trying to spend as little as possible from this point forward, so I'll be salvaging everything I can from this Honda and from local scrapyards combined with a huge junk heap on my family's hunting land.
Should be enough angle iron and tube steel out there for my purposes.
I do have one concern about that Honda though. It's 4x4 shaft driven. I've read that shafts on carts cause a lot more headaches than they're worth. So we're thinking we can convert it to a chain drive somehow.
My buddy has some interesting design ideas, so once I have decent sketches of it I'll post those too, and I'll try to update this thread as I go. Thanks for lookin.

Bdog

 

[landuse]

Welcome to the forum. It looks as if you are all set with that Honda. Post pics and sketches when you have some, and we can then give you some advice if you need it.

 

[Bdog]

Still mainly brainstorming at this point, but I have a question as to how to gear this thing. We're going to mount a sprocket instead of using the shaft drive, and will most likely have a jack shaft between the transmission and the rear axle. My question is gearing.
Since it already has a 5 speed transmission, how do you determine what size sprockets to use on the tranny, jack shaft, and axle?
I'll be using 25" ATV tires, and going more for power than top speed since I'll be lugging two adults in this thing. So top speed of maybe 45?
Here the gear ratios of the transmission:
Primary: 2.407
Final: 5.684
Gear ratio, SL: 4.083
1st: 2.388
2nd: 1.608
3rd: 1.178
4th: 0.848
Reverse: 5.396

I'm learning how all these things play into each other, so bear with me.

Bdog

 

[cpt.skier]

Would the name bdog happen to come from phil casabon?

 

[racerc2000]

what was the factory speed and power like? if it was about what your looking for.

you can turn the driveshaft and see the original ratio to the axle.

and gear accordingly

im sure a 300cc could easily tote 2 adults to 45+ without breaking a sweat. so stock gearing for stock size tires?

or mod it for smaller or larger tires?

 

[Bdog]

Started tearing apart the Fourtrax. Still trying to decide how to mount the engine on the back of the buggy while making use of the existing transmission. I could mount it sideways, but its like 18" wide which is causing me misgivings.
If I remove the shaft drive and mount a sprocket on the rear output, it would be way over to one side of my jackshaft.
I thought about just using the existing shaft drive, but I want to run independent rear suspension instead of a live axle.

I should have some design brainstorms up soon. I'm making good progress learning Google Sketchup.

 

[racerc2000]

are you trying to keep it 4wd?

if not you could use all the front end drive axles. for the rear and make up some new rear suspension.

you should be able to turn the engine sideways. the driveshaft setup should slide off the motor and leave a shaft with gear.

you would have to make an adapter if they dont sell one but you can connect that directly to the front half of the driveshaft.

note: hoping the rotation is the right way. if its not you may have to turn the engine the other way and have a jack shaft run under the engine to the driveshaft.

well good luck

 

[Bdog]

Taking stock of materials I already have on hand, I'm wondering about my frame choices. I've got quite a bit of 1 1/2" and 2" tube steel with 1/8 inch walls, but it seems like it would weight a ton by the time I got done with it.

My other option is one that most people on these forums disapprove of from what I can tell: aluminum.
I've got 50' of 2"x6"x1/4" C-Channel, and a good pile of aluminum 2" and 1 1/2" pipe with 1/8" walls.

I've determined that I'm not doing my own welding, and the guy that is going to do it says he can do aluminum, but is it worth the hassle? I figure I could use the C-channel for the chassis and the tube for the cage and stuff, but I'm wondering if I shouldn't just take everything I've got laying around to a scrapyard and instead buy a whole bunch of something else.

Any thoughts?

 

[4wd_for_field]

i would cut the fram just in front of the engine, and mount that whole lot to the back of your frame, just seriously beef it up. this way you can use the original back end, which solves some serious head aches with axle mounting etc.

 

[Bdog]

I've actually gotten quite good at Google Sketchup in the last 2 weeks. Here is my frame design. I don't have the suspension mocked up yet. Going to do dual chain driven trailing arms on the rear and the atv original a-arms in the front.
I've given up on aluminum though. I think I'll hock all my scrap and get some decent steel tube to work with.
Its amazing how much I've learned on here in such a short time!
Now to sell an antique tractor and some old snowmobiles for money to buy a welder and more power tools...