Long Nguyen
Veteran
Location: Ho Chi Minh City, Vietnam
My Posts This: Topic Forum | A quick calculationI got a brand new main gear so I took it out for measuring and calculating.
There are 124 teeth on a stock main gear. 3.1mm is the pitch range (distance between the top of one tooth and the next one) --> 124mm * 3.1 = 384.4mm is the outside circumference of the gear --> the radius is: 384.4mm/2/pi
We are aiming for a lower tooth main gear, so in order to maintain the pitch range we have to decrease the radius of the main gear.
Right now, on my Synergy I'm using 1mm shims at the engine mounts. In order not to sand down the engine mounts, the decrement in the main gear's radius must not go over than 1mm.
So here is the main calculation:
Let x is the decreased teeth
--> the new circumference = (124 - x)* 3.1
--> the new radius = (124 - x)* 3.1/2/pi
--> the difference between the new radius and the old one = 284.4/2/pi - (124 - x)* 3.1/2/pi
This difference must not go over 1mm so we have the below inequality:
384.4/2/pi - (124 - x)* 3.1/2/pi <= 1
solve that inequality, we got x <= 2.02 --> so it means we can just reduce 1 or 2 teeth at max...--> impossible to have a 118 tooth main gear
If we want to take 6 teeth off, the radius will decrease 2.96mm and that is a lot.
However, above is my calculation and there are many errors in my measuring job (I don't have equipments). The errors could dramatically effect the results.
We could in crease the pitch range a little pit to increase the radius however, the gear mesh will be effected negatively.
Long Nguyen
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