Gear ratio info?

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d_gizzle

d_gizzle

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Can someone PLEASE help me with this!

Seriously, I am trying to find a formula or ratio calculator for 3 and 4 gears,for sbp's shift kit, and for something I'd like to try. By 3 gears I mean something like- 20t/72t~1st gear-8t/48t~2nd gear-30t/34t~final drive.


I'm not sure on the terminology. All advice will be considered and most likely applied.
 
shwnrttr

shwnrttr

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heres what i use. download the link in this thread. you can open multiple ones on your desktop to see multi ratios. if you have any questions click the help button on the calc. let me know if you have additional questions
 
d_gizzle

d_gizzle

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Thanks for the link but I tried that one just now and last night I think with the same results. I'm on a blackberry torch so I can't use it. Maybe a formula?
 
The_Aleman

The_Aleman

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The formula is to multiply each reduction by the next one in line. It's really quite simple. It's up to you to keep track of multiple speeds tho!

For example, a chinagirl on a default SBP kit will be 6.97:1 at the jackshaft output (4.1 * 1.7) because (20 -> 82 -> 10 -> 17).
 
d_gizzle

d_gizzle

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Thanks aleman. I just tried that and what I got was:20/80=4:1,8/48=6:1,26/34=1.3:1 for a final ratio of 31.2:1. Is that right?
 
The_Aleman

The_Aleman

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Close enough. I get 31.38:1. What are you trying to set up? If you're trying to shift kit a 4:1 4G, you're not accounting for the jackshaft.

With the SBP jackshaft figured in (1.7:1 between 4G and jackshaft output), your ratio is actually 53.35:1
 
d_gizzle

d_gizzle

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I'm trying to make a jack plate for tranny with the output shaft all the way to the pedal side,similar to a shift kit but minus one chain.
 
d_gizzle

d_gizzle

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That looks pretty nice. I'm doing something similar,but different enough to be marketed.


Would know of a clutch bell like the one in a 4G,but with a chain sprocket? That would help immensely.
 
The_Aleman

The_Aleman

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I guess that would depend on which motor you're using. If it's the 5/8" keyed shaft model, then no, there's no clutch drum like that readily available. You'd have to custom make it. If you have a tapered shaft engine with the 78MM clutch, there's quite a few different types of clutch drums available for that. Many go-peds, pocket bikes and Staton's stuff use that size. Offhand, I don't know where to get one tho, I'd have to look around for a bit.
 
d_gizzle

d_gizzle

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Its the 5/8 straight shaft. I was just trying to see if I was wrong. I may just get a 5/8 keyed shaft filed to 15mm on one end so I can use the 80t pulley I have.
 
d_gizzle

d_gizzle

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Hey ale,you said nashmoto used the 4G,but that's a "stage 3 whopper stopper" right? That's the taper shaft or the 5/8 shaft? If its the 5/8 shaft,do you know of anyone selling them new? The tranny by itself.
 
d_gizzle

d_gizzle

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I just found one at helio. And I should have known that. He uses the honda,its only a 5/8 straight shaft,can I get an amen?
 
The_Aleman

The_Aleman

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d_gizzle said:
Hey ale,you said nashmoto used the 4G,but that's a "stage 3 whopper stopper" right? That's the taper shaft or the 5/8 shaft? If its the 5/8 shaft,do you know of anyone selling them new? The tranny by itself.
Click to expand...
He started with the Stage III, but I also said:

The_Aleman said:
Scroll down to January 25th and earlier.
Click to expand...
There you can see that he uses a custom 4G-based system. At the moment, I don't know any reputable vendors selling the "Honda" style 4G itself.
The good vendors have been out of stock for a few months.
 
d_gizzle

d_gizzle

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That's my bad aleman,I didn't see the cover and then I went dumb cuz his work looks good. I'm doing more of the "poor mans" version. Something everyone with a 4G could consider for a jack shaft. With 4 freewheels in only 3 gears maybe
 
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