Track Tac

gearing using a jackshaft

take your primary ratio (engine to jackshaft) times your secondary ratio (jackshaft to axle)
typical 2 stroke buller set up 21/57 =2.71 times 13/60 =4.61 2.71 times 4.61 =12.53
buller and "al" have a chart as well.
 
There are 2 gear ratios, actually 3. The primary; from the engine to the jackshaft, and the secondary; from the jackshaft to the axle. Then there is the overall; from the engine to the axle.

If you multiply the secondary, by the primary, you get the overall. If you have Excel, or one of the clones to Excel, I have a spreadsheet that will do all the math for you. You put in the primary gears, and the secondary gears, and it gives you the overall. You only have to put in the primary gears one time. You can change them, but I don't think, on the average, people change their primary very often.

Send email to; anunley@austin.rr.com It's free to anybody that wants it.

There's a whole bunch of other stuff in this software too. Over 20 pages of utilities for karting. My spreadsheet for corner weights, is very very good.
 
With a cheap calculator it's very easy to make your own chart, all you need to remember is to divide the smaller numbers into the larger, then multiply the answers for the primary and 2ndary sides, to get your over all ratio.
 
jack burroughs said:
With a cheap calculator it's very easy to make your own chart, all you need to remember is to divide the smaller numbers into the larger, then multiply the answers for the primary and 2ndary sides, to get your over all ratio.
Click to expand...
LOL is easy better than free? And what could be easier than looking at a free printed chart?
 
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