TAV and fat tires

jeffe

jeffe

Member
#1
#1
So, I'm thinking about a tav for my fat bike, I guess I really should have designed it around one... My homemade setup uses a 3/4" jack shaft and a 1/4" plate. There's about 2 1/4" between the jack shaft sprockets. I'm thinking I could almost make a tav and backplate work if the sprocket was on the outboard side of the driven pulley... Is that possible? Not recommended, dumb, or dangerous? Would the backplate flex too much?




 
minibikin'

minibikin'

Sho-nuff
#2
#2
You can run it our word but you'll need a longer 5/8" shaft and some collars/spacers


Sent from my Texas Instruments Speak and Spell...[emoji2]
 
Sixpac440

Sixpac440

#3
#3
Seat of my pants thoughts ...

Buy a TAV setup ... it will have the correct distance ect built in .. put a jackshaft in front of your back wheel ... you can turn the wheel around if need be ... also you can set up a band brake on the jackshaft ...

my 2 cents ...
 
jeffe

jeffe

Member
#5
#5
Sixpac440 said:
Seat of my pants thoughts ...

Buy a TAV setup ... it will have the correct distance ect built in .. put a jackshaft in front of your back wheel ... you can turn the wheel around if need be ... also you can set up a band brake on the jackshaft ...

my 2 cents ...
Click to expand...
Thanks, yeah, I was thinking of using the tav aluminum back plate, not my homemade one. Being lazy, I guess, thinking of ways around welding a jack shaft on.. :smile:
Can't turn my tire around without a bunch of work, I have a disc brake on the right side.

 
jeffe

jeffe

Member
#6
#6
Well, that only took a year and a half.. :)
The jackshaft plate I had made got bent, so I figured this would be a good time to mess around with a cheap TAV.

I guess we'll see how this holds up, I have the sprocket on the outboard side of the driven pulley. I was able to use the original shaft, with three washers behind the driven to space it out and by grinding just a little off of the backplate fins. Oh, and by using a 5/8" thin locknut..

The driver is spaced away from the engine (a Tecumseh I got cheap) with two washers. I went with the Tecumseh because it fits the Tav like it was meant to be.. :) Which saved me modifying the frame or lifting the engine up, although I had to move the engine to the right about half an inch. I could have moved the sprocket over, but the chain would hit the tire. Still might have to fine tune the alignment.

I'm waiting for the carb to arrive, then I'll be able to try it out.

Too bad about photobucket, but there are pics of the bike in my 'rides'

image.jpeg image.jpeg image.jpeg
 
jeffe

jeffe

Member
#8
#8
Raskin said:
Looks good..:thumbsup: must have some good top end..whats engine hp?
Click to expand...
The clone that was on it before was modified a bit.. Some porting, re-jetting, arc rod, Pvl flywheel, no gov. You'd probably be a better judge of the hp than me... :)
It was geared about 13:1 with the old clutch, so it didn't go super fast, but would climb like crazy and go thru lots of snow.

The new Tec motor is a 5hp, stock for now, except I ordered a primer bulb-less carb for it. I'm hoping it goes okay, although our old go kart with a five horse Briggs and Tav would pull a kid (or me) on a sled with no problem.
 
danford1

danford1

#9
#9
Having that sprocket on the end of the shaft exerts A LOT of force on the bearing plate. The leverage of the shaft can't be good for bearings etc. Just my opinion, others may vary but I don't feel this is a good idea.
I'm not saying it can't work, I just don't know about longevity...
keep us posted how it works out for you.
 
jeffe

jeffe

Member
#10
#10
danford1 said:
Having that sprocket on the end of the shaft exerts A LOT of force on the bearing plate. The leverage of the shaft can't be good for bearings etc. Just my opinion, others may vary but I don't feel this is a good idea.
I'm not saying it can't work, I just don't know about longevity...
keep us posted how it works out for you.
Click to expand...
Thanks, yeah, I know it's not optimal. I may end up putting a jackshaft behind the Tav running between a pair of bearings.. as was suggested above.. :smile:
But, I'll give this a try and see how it goes.
 
C

control4userguy

New Member
#12
#12
danford1 said:
Having that sprocket on the end of the shaft exerts A LOT of force on the bearing plate. The leverage of the shaft can't be good for bearings etc. Just my opinion, others may vary but I don't feel this is a good idea.
I'm not saying it can't work, I just don't know about longevity...
keep us posted how it works out for you.
Click to expand...
Come again? Where's that drive sprocket suppose to sit?
 
Charles S

Charles S

#15
#15
danford1 said:
Having that sprocket on the end of the shaft exerts A LOT of force on the bearing plate. The leverage of the shaft can't be good for bearings etc. Just my opinion, others may vary but I don't feel this is a good idea.
I'm not saying it can't work, I just don't know about longevity...
keep us posted how it works out for you.
Click to expand...
I thought the same when I saw it. Maybe a longer driven shaft with an outboard bearing would work. A jackshaft bearing plate (or something similar) could be welded to the frame. Better yet, IMO, would be to fabricate an aluminum or steel bolt-on TAV cover (use the existing cover mounting points) that incorporates a bearing carrier. Use clamping collars on the shaft; much better than the set-screw collars, IMO.
 
jeffe

jeffe

Member
#16
#16
Here's the old drive setup. That 1/4" plate bent enough to throw the chain, now , I don't know if the chain coming off bent it more or what. Also, the bolt from my exhaust bracket was gone, so it could have gone thru the chain and added to the bend, but I doubt it...

This was after a couple years use, however. The aluminum Tav plate isn't likely to bend, though, it'll just snap in half..:blink:

image.jpeg
 
Raskin

Raskin

#17
#17
My 2cents..which may get you a penny..:laugh: move the engine over to put the sprocket inside the driven and also get a bigger rear sprocket..it looks a bit like a cruiser w that gearing and a 5hp
 
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jeffe

jeffe

Member
#18
#18
Raskin said:
My 2cents..which may get you a penny..:laugh: move the engine over to put the sprocket inside the driven and also get a bigger rear sprocket..it looks a bit like a cruiser w that gearing and a 5hp
Click to expand...
The original gearing was 13:1, well 12.96:1. 10-24-10-54 , the tires are 22"
Good for our rooty trails :)

And moving the engine over that far would almost put it outside of the frame, with the fat tires..
 
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C

control4userguy

New Member
#19
#19
jeffe said:
They're that bad, hey? Well, hopefully, I receive one of the ones that works out of the box.. :)
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Didn't say they were bad. I just find it amusing that so many folks have a distaste for squirt-start carbs. If you like a choke plate in the airstream and the chance or two you forget to flip the lever back then go for it.
 
Charles S

Charles S

#20
#20
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