jackshaft gear ratio

[bigdaddy4026]

i get different readings every site i figure it out on:shrug:

intek 6.5 max torgue 12 tooth

jackshaft in 13 tooth

jackshaft out 20 tooth

rear wheel 72 tooth

11.5" tall rear slick

just trying to figure ratio, engine rpm,and possible mph,

don't want him to blow it up in 660ft:thumbsup:

 

[drbhuntnfish]

I did a quick calculation - so it should be checked. The weird thing about a jackshaft is that regardless of the number of teeth, the both sprockets travel 1 revolution at the same time. So to calculate gear ratio based on number of teeth, you don't ratio the jackshaft sprockets to each other in the calculation.

Instead you do this:
(13/12)*(72/20) = 3.9 final gear ratio

If the engine is turning 3600 rpm max, then the max speed would be:
Engine RPM/final gear ratio = 923 rev/min (for rear tire)
923 Rev/min * distance traveled/Rev = 923Rev/min * 3.01 ft/Rev = 2778 ft/min

2779 ft/min * (60min/hr) / (5280 ft/mile) = 31.6 mph.

Hopefully someone else will check it as well...
drb

 

[bigdaddy4026]

wow thats alot of math!:laugh: my brain started smoking reading it!:doah: thanks that gives me some kind of idea:bowdown: