Author Topic: Twist's extremely simple guide to calculating gear ratios/ estimated ROF  (Read 760 times)

Offline Twist

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Hello! Have you ever received a rifle off of a trade including unmarked gears? Or would you like to know the ratio of that random gear set you have in the bottom of your parts box? Or would you like to get a general perspective to your ROF difference if you changed your gear ratio?  In this thread I will show you the two very simple formulas to answer these age old questions. Now if you are an experienced tech there is a 99% chance you already know these like the back of your hand so this thread most likely isn't important to you, how ever if you are new to "teching" then this is the thread for you!

Calculating gear ratio: for this formula you will need to count the teeth specified. Sector out/ spur in * spur out/ bevel in * bevel out/ pinion in = Your exact ratio : 1. For a visual example here are the calculations from a standard 18:1 gearset. 32/20 * 39/10 * 30/10 = 18,72 ~ 18:1

Estimating RPS changes due to ratio changes: with this formula you will be able to create a theoretical estaminet on how your RPS will change if you ONLY switch your gears (NOTE: shimming DOES affect this calculation). This one is a bit different to explain so I'm going to use an example using standard 18:1's as the subject. So let's say that you are currently obtaining 20 RPS on your stock 18:1's, you would take your exact ratio 18,72 X 20 = 374,4 / second. Now you decide you want to switch to 16:1's ==> 374,4 / 16 = 23,40 RPS, so theoretically you are obtaining an increase of 3,40 RPS with your new gears.

I hope that this guide helped some of you new comer tech's!