Topic: gearing a 700

[mowcephus]

Are they a forumla for figuring out a gear ratio for these things?  For example we run approximately 300 feet tracks and I run 16x7.5x8 tires on the rear.  How can I figure out how to set this thing up without having to do it all at the track?

[matt25001149]

if ur tranny is in and everything is hooked up shift into your desired racing gear and mark your pulley and your frame then turn it until your wheel makes one complete turn while doing this count the amount of times the pully completes a turn  then for and example it turns out your ratio is 12:1 wich means pulley turns 12 times to your wheel turning once then divide that by your engine rpm say thats 6000 rpm

12 divide 6000 = 500

wich means there is 500 rpm art the axel then multiply that by 4.33 for a 16'' tire

500 rpm X 4.33 ft = 2870.70 ft/min

(tire circumference = 4.33 ft [16" tire])

2870.70 ft/min X 60 min =  ft/hr

172242.204 ft/hr / 5280 = 32 mph

[matt25001149]

buuuuuuuuuuut that is only if your running a 1:1 pulley ratio now if your runnin a 2:1 then u have to double your engine rpm before you divide it by your ratio

using 12:1 as an example you divide 12000 rpm by 12 ull get 1000 axel rpm then  u put that into the formula i gave you then u get your speed
yay LOL
 

[George Herrin]

Dang that confused the heck outta me!!! Just check it like an IMOW. If and SP you want it in the neighbor hood of 6 to 6.5 to 1. Thats turns of the motor to 1 turn of your tire in your race gear. Which on my SP was a 8 on motor 5 on tranny and a 15 tooth to a 50 tooth. And I raced in either second or thrid depending on track. If a BP I have never checked it like an IMOW but all I have built I have run a 8 on motor and a 5 on tranny then a 12 tooth to a 44, 46, or 48. 98% of the time I run a 46. This will put you in the ball park at most tracks.

[mowcephus]

Yeah I'm kinda confused too, but I tryed doing it in 6:1 ratio and I came up with 49 mph.