gear set ratios?

[CJC]

Hi all. I've got a vfc m27 that I have converted to a dmr. Currently running an m135 spring with a tienly gt45000 motor and a MOSFET/rewire on the stock gears and its very loud and a tad screechy. The motor height is fine but the gears are self shimming so I want shot of them soon. I was just wondering if I could get away with a strong set of 20:1 siegetek gears or would I need to step up to torque gears? Also if anyone knows how good the modify modular gear sets are please let me know and if anyone can explain to me how the ratios affect everything such as ROF etc that would be very nice. Im just worried about not having a very snappy trigger response if I put a torque gear set in. All advise welcome. Thanks.

[Mickydoos]

Re: gear set ratios?

The gear ratio simply states how many times the motor is required to spin at the bezel gear to produce a single rotation on the sector gear (the one that pulls back the piston)

18:1 is considered "standard gearing" meaning the motor must spin the bezel gear 18 times for each turn of the sector gear (and therefore one shot)

Now consider a "high speed" set with a 13:1 ratio. This means it takes only 13 turns of the bezel gear to produce one shot.

A "high torque" set with a ratio of 20:1 will require 20 bezel turns etc

So in 234 turns a 13:1 gearset will fire 18 times and the 18:1 gearset will fire 13 times and the 20:1 will fire about 11-12 times (11.7 to be precise).

Now there's side effects here at play. A gearset that requires fewer turns (high speed 13:1) will put more strain on the component supplying the power (the motor) and will require more torque. Hence the need for high torque motors.

[sj_asc]

Re: gear set ratios?

The GT45K, even though having a fast wound arm will still have plenty of grunt for an M135 with the stock 18.7:1 gears, so Riots 20.8:1 set will be higher, making life on the motor.
VFC's self shimming gears are terrible by comparison, and the bevel it's self will need shimming in accordance with the motor pinion gear to eliminate that screech before bothering with the motor height adjustments.

Note that even though Tienly's Pinions are great, you could grab one of Riots Nicromoly steel Pinions for further optimised compatibility and better durability.