Multiple sprocket gear ratio??

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brosgoboom

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So, my go-kart has an interesting drivetrain setup. I've been trying to figure out my gearing ratio(which came with the frame when I bought it) although I cannot use a calculator as it has multiple sprockets throughout the drivetrain. I am using a 420cc Predator Engine(Governed but I may change that) with a torque converter. There is a total of 4 sprockets including the axle and torque converter. The sprocket on the torque converter is a 12 tooth, which connects to a 24 tooth sprocket on the end of a shaft mounted horizontally under the engine mount. On the middle of the shaft, there is a 10 tooth sprocket that connects to a 60 tooth sprocket mounted on the middle of the axle(which has a differential). I am using 18-inch wheels. I have tried calculating the ratio manually but I am not sure if I am doing it correctly, so I was hoping someone could explain how you go about doing so. I will post the specs below for convenience. Any help is appreciated!:thumbsup:
(Sprockets in order from torque converter to axle)
12 tooth
24 tooth
10 tooth
60 tooth
18 Inch rear wheel diameter
420cc Governed Stock Predator Engine (Approx 3600 RPM)

Thanks :)
 

Bbqjoe

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I'm going to venture to say, in the end you're still delivering 6:1 to the wheels.
I don't know from what the wheels are seeing.
 

brosgoboom

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Got it figured out

I am not very acquainted with jackshafts, I'm more of an engine internals guy, but I did manage to find the jackshaft calculator a little after that. I don't know if the previous owners were fixing to pull stumps or what, but I have another 10 tooth sprocket to replace the 24 tooth, which gives me the good ole 5:1 12-60 tooth reduction. Anyhow, thank you guys for your help, I appreciate it. :)
I would post pictures but my phone is broken right now so I cant, although I'm most likely going to chop the entire frame and mount the axle on the top of the floor pan so I can get it real low, along with putting a Harley muffler on it. I reckon itll look pretty cool with the big 18's in the back and maybe some 15's in the front, give it that tilted dragster look. Ill post pictures when I get a new phone anyhow because I also have no clue who produced this go kart, I havent seen a chassis like it before personally.

UPDATE: Scratch that, I was able to find an older pic of the kart
http://www.diygokarts.com/vb/showthread.php?p=464935#post464935
 
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itsid

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12:1 chain ratio plus ~2:1 for the TC.. 24:1 max ratio (wow that's some serious torque :D)

chain ratio is actually simple: divide the toothcount of the driven axle by the toothcount of the sprocket driving it:
(60/10 ... -> 6:1)

and repeat this step in this direction until you meet the engine multiplying all steps...
6:1 carry over... next step 24/12 (2:1)

sprockets that run on the same shaft rotate at the exact same speed can be ignored during calculation ;)
(they'd run 1:1 so you'd multiply by one.. which is rather pointless )

6*2 =12 12:1 chain ratio.
12:1 internal TC ratio can be looked up... assume 2 for now:
12 * 2 ->> 24:1 overall ratio

'sid

PS I don't know what weight this thing has to push around,
but yes, I'd say you could easily double the speed by just replacing the 24T sprocket with another 12T one ;) (making it effecitvely a 6:1 chain ratio.. which should be more than good for an engine that size)
 
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