Gear Ratio

[jarcynvicnchris93]

Ok I need some help with gear ratios- If my live axle sprocket does not give me enough ground clearance-can I instead add a second jack shaft and run three sprockets-two large and one small. essentially dividing the big sprocket by two thus reducing the size. this seems right but Im not sure. right now I think I am running a 12 and a 72. (do not have the kart here to look at right now) but the 72 is huge and does not give me the clearance I would like to have.

 

[Kenny_McCormic]

You mean like the clutch running to a big one on a jackshaft driving a little one that goes to a big one on the axle? No problem with that.

 

[brendonv]

well ur ratio for 12T to 72T is 6:1. So u could go 10T to 60T,10T to 60T. U wouldnt want to go from a 11T to 66T,11T to 66T or 9T to 54T,9T to 54T because there not as available as a 60T and a 10T. If you cant get a 10T clutch then go 11T to 66T. If your making a go kart you dont need a jack shaft, just go 5:1 so 12T to 60T. 5.5:1 is also good if you can get a hold of a 66T sprocket.

Hope that helps.

 

[jarcynvicnchris93]

I did not give enough info

well ur ratio for 12T to 72T is 6:1. So u could go 10T to 60T,10T to 60T. U wouldnt want to go from a 11T to 66T,11T to 66T or 9T to 54T,9T to 54T because there not as available as a 60T and a 10T. If you cant get a 10T clutch then go 11T to 66T. If your making a go kart you dont need a jack shaft, just go 5:1 so 12T to 60T. 5.5:1 is also good if you can get a hold of a 66T sprocket.

Hope that helps.

sorry I should have given more information

I am running a Comet Series 40

My engine is mounted on BMIs Jackshaft plate. of course the jack shaft drives a 12 tooth sprocket to a 72 on a 1" live axle. Works great however I would like more ground clearance. so I was thinking of running a 36 on my axle to another 36 on a front jackshaft to the 12 on the main jackshaft running from the series 40... does this even sound close to right. Also I am running 22" tall 10" wide tires in the rear of the kart. I was running the 6 to 1 so I can turn the big tires.

 

[jarcynvicnchris93]

60 tooth

if I run a 60 tooth on the axle with a 11 on the jack shaft would that turn the tires and still give me low end torque?? I have heard of Quads running 16 tooth front and a 60 tooth on the axle. but I know Quads are diff than what Im doing

 

[brendonv]

thats what im going to be running on my kart, 11 to 60. Its almost a 5.5:1 ratio (5.45*:1 to be exact)so ur going to be halfway. Ur going to have good low end torque and good top speed. Its not going to be as good low end as a 6:1 but not far off it, u will also get the great top speed of a 5:1 ratio so its a really good in between ratio.

 

[jr dragster T]

6:1 is your ideal ratio.

 

[jarcynvicnchris93]

ideal ratio

I understand what your saying Tyler however; my axle sprocket is 12"in diameter running a #40 chain to a 12 tooth sprocket on the jackshaft. and even with 18" tall rear tires I do not have the best clearance. (3") I would like as much ground clearance as I can get and still have low end torque and some top end.

but even by going to a 60 tooth #40 chain sprocket I would only gain 1" of clearance. So I think I will keep what I have.

 

[Scout]

well ur ratio for 12T to 72T is 6:1. Good so far. So u could go 10T to 60T,10T to 60T. That's 12:1. 10 to 60 is 6:1, then another 10 to 60 is another 6:1 on top of that, making 12 to 1 U wouldnt want to go from a 11T to 66T,11T to 66T or 9T to 54T,9T to 54T because there not as available as a 60T and a 10T. If you cant get a 10T clutch then go 11T to 66T. If your making a go kart you dont need a jack shaft, just go 5:1 so 12T to 60T. 5.5:1 is also good if you can get a hold of a 66T sprocket.

Hope that helps.

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