Things to consider when going High Torque

[Bar1975]

Just picked up a set of King Arms Normal Torque gears.. (72:1 ratio i believe)

I'm running

- SHS High Torque Motor
- 11.1 Lipo
- M120 Spring

Is there anything i should be aware of here?

Is this too weak of a spring for this set up? (I have to keep fps <400)

The new SHS motor just completely destroyed my stock gears so hoping that it wont do the same to the new King Arms gears..

[Stealth]

Why did you get a Torque gearset with a high torque motor to pull an M120 spring? Your ROF will be mega slow and your motor will be working under its peak power efficiency.

I would MAYBE use that setup to pull an M190 spring, but I wouldn't get King Arms gears in any case. Get standard ratio or faster (18:1, 16:1 and 13:1)

A high-torque motor should not destroy a gearset if the gearset is of good quality.

[Hectic]

I was gonna say thats a light spring for high torque. (i was leaning towards 170 plus but stealth knows his shit so 190 it is lol)
Also id suggest that motors dont really distroy gears (unless its bad pinion to bevel alignment) its mord or less bad shimming aad bad AOE that kills gears.

[ThunderCactus]

They don't even make 72:1, and if they do, you'd either need a 4th gear or a huge slot in the piston to fit it lol
Max torque ratio is 45:1
Normal ratio is 17-20:1, and that should be just fine for 400fps

Your gears probably stripped due to poor installation or poor quality

[MaciekA]

Your normal ratio gears are likely 18:1. The King Arms website says 72:1, but that makes no sense, and the picture shows 18:1, which would align with the general meaning of "normal" in this context.

That aside, everything should be fine, but the fact that you blew up your previous gears should give you pause. You need to make sure that you don't have any piston binding, that your gears spin freely, and that you have corrected for angle of engagement. Unless your previous gears were complete garbage (actually quite rare), you must have had binding or lack of AoE or some related issue.

At 11.1V and a modern neo motor, the above factors will be of concern.

Additionally, the SHS high torque motor is a bit of a pig when it comes to power. You will be pulling a lot of current over your contacts, so I hope you have upgraded beyond Tamiya connectors and have a MOSFET.

[Bar1975]

So i have the gears in my hand and they in fact state "72:1".. so no questions in regards to these gears don't exist.. unless im seeing things

The reason behind the High Torque motor + gears is that im running a CYMA AK-47 with a recoil/blowback engine that came stock with the gun. A rather heavy weight is attached to the gearbox and it gets pulled back with the piston. The gun came with a rather high torque motor but i figured the SHS would do a better more efficient job. I don't care about ROF with this particular set up..i just want a nice crisp action on semi for the most part.

For the past few weeks the gun has worked like a charm until this past weekend when i didn't have my 11.1 with me and opted to use a 9.6V. (Would a lesser voltage battery cause any issues with the gears?)

The SPUR and SECTOR gear just got destroyed.. missing teeth on both.

So now i have the high torque steel gears (King Arms or not they have to be better than the stock gears)

I am leaning towards disabling the blowback/recoil engine if this is going to continue to create un-wanted wear and tear of the gearbox.. the novelty has long worn off anyways. But with the blowback removed.. will the high torque set up create new issues? Maybe it makes sense to keep the blowback turned on to warrent a high torque set up..

otherwise then yes.. im just pulling a M120 with a high torque set up..

recommendations?

[Hectic]

If the upper/small portion of the spur and the botom/full gear section of the sector is what stripped it means that most likely the spur was too high or the sector was too low OR the spur was too low and sector too high (depending if the teeth wer kind of shered half way or if they where totally chewed right off (chewed right off would most likely be they wer too tight together and shered half off would be they wer too far apart from eachother.

[Bar1975]

they were completely broken off.... i was picking the teeth out of the gearbox.



the gun was running fine on the stock motor.. this only happened with the new SHS Torque motor...

[Hectic]

It was going to happen regardless of the torque motor or not. Is the gun brand new? Was it opened by you or someone else in the past? Either way the most likely cause is bad shimming a high torque motor wont just sheer off teeth. Failer due to a high torque build will most often be due to the heavy spring so either the piston will sheer teeth or if its a full metal rack it may sheer teeth off of the half gear part of the sector gear. Or the pinion can stripp if it just cant pull the spring.
But for sure the high torque motor isnt the cause of the stripped gears especially in that location.
Going high speed will sometimes strip stuff but most often the piston.
Shimming was for sure the culprit and or the bushings could be loose causing the gears to wobble a bit giving the same sort of shmptom as bad shimming.

[ThunderCactus]

It's a complete LIE.
72:1 would lower your ROF with a normal motor and 11.1v lipo to around 400-500rpm lol

I'm running 26:1 in my 249 with mosfet, 11.1v and torque motor and I'm getting 1400rpm

[Bar1975]

after reading other posts i can see that these ratio's are sometimes not what they appear to be.(for example 200:100 are - 23:1, and 300:100 - 26:1...)

Not sure where 72:1 nets out but im going to throw these into this AK.. im going to reduce the recoil weight (removable counter weights inside) and hope for solid (all be it slower) gun performance. (i've got plenty of high ROF projects on the go.. this one is about reliability)

am i way off here?

[Bar1975]

Originally Posted by ThunderCactus

It's a complete LIE.
72:1 would lower your ROF with a normal motor and 11.1v lipo to around 400-500rpm lol

I'm running 26:1 in my 249 with mosfet, 11.1v and torque motor and I'm getting 1400rpm

What Spring are you running with this set up? (i have to keep it <400 FPS)

This gun has a great air seal ..with the M120 i have in it now im over 400FPS but allowing it to settle into a range that's <400 (it's a new spring)

[Bar1975]

Originally Posted by Hectic

It was going to happen regardless of the torque motor or not. Is the gun brand new? Was it opened by you or someone else in the past?

It is a new gun and i did open it and tune it a little. I did re-shim as well but in hindsight i didn't spend a whole lot of time shimming. (I didn't have a full set of shims so just slightly tightened everything up a little as it was a bit loose stock)

I have the new gears in now and just spent a couple of hours shimming. With gearbox closed up they spin freely with no apparent metal on metal noise.. there is very little vertical play in the axles (i used .1 to fine tune) They spin for several cycles freely.. this has to be good enough..this aint no Ferrari transmission

I've polished the inside of the gearbox to an almost mirror like reflection with various weights of steel wool.. checked the piston and tappet plate movement and everything is moving freely.

Completely de-greased and re-greased all parts..

I can't think of anything else that i can do but get it all back together and give it a whirl..

[ThunderCactus]

249s at 385fps
it's 1400rpm with my EF1300, which is high torque
it reaches around 1550 with a G&P M140, which has higher RPM, but the M140s aren't nearly as reliable as the EF1300

[Bar1975]

I don't understand how springs above the M120 (comparable brands) range can still come in at less than 400FPS?

I'm at 400FPS now with an M120... any higher spring gauge than that and i can't use the gun anymore..

Does anybody know if the 72:1 Gear Ratio is in fact legit? Will it now take me 5 seconds to complete one single shot?

Also.. with the higher torque set up i guess it makes sense to keep the recoil/blowback engine in tact?