Topic: PULLEY CHARTS

[DJROMANOX]

Does anybody know if there is a chart on gearing up pulleys?




THANKS

[George Herrin]

A chart for what! Maybe I am missing something here.

[kmowtion]

No George, I don't think so... If you are, then so am I!!!

If you can specify more what you are looking for, I may be able to hook you up with something. Your question is very vague. Who do you race with, and how big is your track?

Pork Chop

[money89tractors]

I would assume (yes i know where that gets me) he is wonder about a ratio chart on pulleys, such as:

4" to 4" = 1:1 ratio
2' to 4" = 2:1

and so on.

-Phil

[Tom Fox]

Calculator

[George Herrin]

OK SIMPLE MATH.

[DJROMANOX]

how could i use a calculator to find a ratio of the pulleys

[George Herrin]

8" divided by a 3" = 2.6666666666666 ratio!!! Simple math

[Squidd]

Then you just have to take that number...multiply it by your tranny ratio and divide by your drive/axle sprocket ratio to get your final ratio...

Which should be around 6.5 by the way...

[overkillphil]

quote by money89tractors:
"2' to 4" = 2:1"

Wow, that would actually be 6:1, but I think you would have alot of fun trying to fit that 2 foot diameter pulley on your crankshaft.  Better put some guards or maybe "deck halves" on either side of that pulley! 

[money89tractors]

quote by money89tractors:
"2' to 4" = 2:1"

Wow, that would actually be 6:1, but I think you would have alot of fun trying to fit that 2 foot diameter pulley on your crankshaft.  Better put some guards or maybe "deck halves" on either side of that pulley! 

lol just giving an example...kinda messed up, but it made the point

-Phil

[Gary Elder]

If he is looking for the final speed, i made an equasion that might help.

RPM's / ratio X 300 / 63,360

for example, if you were running in a governed class (like imow) at 3500 RPM's and running an 8:1 ratio, it would work like this. This is assuming he's using a 16" tire.

3500 / 8 X 300 / 63,360= about 21 MPH

I think its accurate, because I have heard imow's run at about that speed.

[mowpower]

Here is what I used trans pulley divided by engine pulley times trans ratio times axle tooth count divided by trans tooth count. Now all this depends on a lot like a 3:1 trans.  So here it is with numbers pluged in        Tp/Ep x Tr X At/Tt    5"/8" times 3 times 42/12   Now for the answer just in case some of you don't understand simple math  (5/8)=.625x3x(42/12)=3.5 so now it will look like this .625x3x3.5= 6.56:1 now this will get you in the ball park but check in the old way. I have found out the hard way just cuz it is a 5in pulley doesn't mean it is a true 5in  If the belt sits down in the groove deeper then it mite be 4 3/4 dia pulley and that screws thing up. Here it is again but using 4 3/4 .593x3x3.5=6.22:1 Which means you may have to go up to a 44 or 46 tooth gear to get you in the 6.5:1 range.  If you are interested I created a chart for the pulley's I use and the Ratio PM me and I will send you a copy.

[George Herrin]

KISS Jack the rear up put it in race gear, turn and count how many times the motor turns to one compete revolution to the rear tire, DONE simple and easy.

[outlawmower]

Are you running transaxle or live axle? If your running a transaxle do this--


Take you rear pulley and divide it into your front pulley, multiply that times your engine RPMs, divide that by top gear tranny ratio(12 if its 12:1) save that number.Then tire size ( 14", 15", 16") X 3.14, take that number X the saved number = inches per min. Multiply that times 60 = inches per hour, divide that by 12 = feet per hour, divide that by 5280 = Miles Per Hour.