Gg Gearbox Lock-up With 13.1 Upgrade

[llure]

Hello everyone,

I'm new in the forum and I would lake to share with you a brekaking nuts problem on my upgraded G&G CM16 SRS.

I have to say that I made the maintenance on some gearboxes, but I never made a high speed build. Always high torque ones.

So.. everything here is new for me xD.

Mounted material:

-I fully obtained, installed and tested a complete SHS set for V2 gearbox. Gears, cylinder, piston, piston guide and nub.

-I shimmed with following the Bevel-to-pinion method.

https://www.youtube.com/watch?v=ZahpxfCsSAY&ab_channel=ChupacabraOutdoor

-The motor Is a Big Dragon M160 High torque.

-Using a Racoon 11.1V / 1350mAh / 25-50cc battery. T-Dean .

-Im using the electronic trigger from G&G. It came installed in the gun.

Facts:

The thing is that I fired some rounds with it. I was enjoying the rof until it suddenly stopped.

The piston it stopped in a intermediate position. I pulled enough time the trigger until the 25A fuse fired up.

So I have many questions about it.

1. Why this happened?? xD

2. When I was making the testing with the gears and motor only (without cylinder, spring, etc) I noticed that in semi the wires were hot af.

In auto, with the trigger pulled they got a little bit warm, but not so much as semi.

3.Related with the electronics... I should mount an active brake on this?

4. Recommended grease for high speed builds? I have some teflon not-branded grease for the compression and WD-40 grease for gears.

Every tip and answer is welcome!

Thanks guys!

 

[Adolf Hamster]

semi is going to be putting a lot more load on the motor per-round than auto.

the locking up could be a bunch of things, but as you found pulling the trigger for more than a second on a stalled motor is a very bad idea- good thing you still had the fuse installed.

i have a sneaking suspicion that the shimming might be tight, remember when shimming to test everything spins freely with the gearbox bolted down- that tiny bit of compression compared to holding the shells together by hand can add a lot of unnessecary load.

 

[Sitting Duck]

First of all...

Big Dragon M160  = very quick high speed motor + 13:1 + 11.1v etc...

Are you fucking nuts ???

that setup is going to hit 45rps on 11.1v and likely has suffered PME etc...

that setup at say 350fps does 29/30rps aprox on 7.4v

So when using 11.1v expect 30rps x 1.55 = 45/46rps

It may have been more sensible to use the M140 motor with 13:1 on 7.4v

or M160 with std 18:1 gears on 7.4v LiPo's to get aroubd 24rps (ish)

or nudging into the 20's there abouts

BD-M160 is just too fast imho and draws too many amps so shit runs too quick and too warm

(please FFS people stop buying the M160 motor - it is toooo fast - no really it is)

Them M160's will not be used as is, but armature replaced with more sensible ones

I mean yeah - you can use them on std 18:1's but still the amps are a bit higher along with more heat

(and over time the extra heat just fucks the bearing at the end bell - they are just too fast/warm imho)

But even on std gears you should get 22~24rps on 7.4v & 35/36rps on 11.1v with 18:1 gears

way too quick for a std UK gun on say m100/105 spring 

at around 25rps it will start to double fire on semi

and to combat this you can Short Stroke it to a point to reduce overspin

even then - it may be OK up to say 30~35rps once short stroked

but approaching the potential speed you have designed it may risk PME at 45rps

(well I've still smashed a 13:1 setup SS 3 teeth on a beefy 11.1v hitting into the forties at 340fps)

They are not a wise choice of motor - even on 7.4v

and on 11.1v - well you are just asking for rebuilds and picking teeth out of your gearbox

and many of us have learnt the hard way about super fast motors & shit

Design a build with a 25k to 30k motor aprox with 13:1's

get into 20's just with a m120 spring SS a few teeth

run with that - or if you want some insane zest a low 11.1v will get you into low 30's

if you done the build perfect it will last for a while, but M160 on 11.1v...

 

[Adolf Hamster]

Man i need to brush up on my motor knowledge, i didnt twig that was a high speed.

Feels like english isnt this guys first language i wonder if he's somewhere with mad fps limits where 45rps is feasable without pme?

 

[Sitting Duck]

Secondly...

if you did this to a G&G SRS with ETU

the ETU likely said fuck it as they are made from Dairylea at the best of times on a mild build

What you attempted to do is create something with high amperage & on 11.1v higher Watts

The cheese spread ETU mosfet said fuck this I'm off and the fuse blew eventually

I had a FFR-A1 which this happened to and even when replacing the fuse it just kept blowing

(the ETU unit in stock tube was fucked)

Now your ETU might be OK, but you was certainly pushing your luck on a reg AEG

and on a ETU...

Man i need to brush up on my motor knowledge, i didnt twig that was a high speed.

Feels like english isnt this guys first language i wonder if he's somewhere with mad fps limits where 45rps is feasable without pme?

Think even US sites at say 400fps AEG with m120 would see PME risk start to creep in from say low to mid 30's

and if done correctly with decent shimming, airseal etc... on a UK spec gun 13:1 m160 11.1v he is looking at 45rps

just asking for trouble - even more so on an G&G ETU 

 

[Adolf Hamster]

Think even US sites at say 400fps AEG with m120 would see PME risk start to creep in from say low to mid 30's

and if done correctly with decent shimming, airseal etc... on a UK spec gun 13:1 m160 11.1v he is looking at 45rps

just asking for trouble - even more so on an G&G ETU

Yeah, i'm thinking somewhere even crazier, i'm not massively clued up on different fps rules for different countries but i know some places it's a case of whatever you can get the gun to do without breaking.

 

[Sitting Duck]

Yeah, i'm thinking somewhere even crazier, i'm not massively clued up on different fps rules for different countries but i know some places it's a case of whatever you can get the gun to do without breaking.

Was it you or somebody else got a Big Dragon M140 cheap from AliExpress with coupons ???

Those are the safe decent motors

the m160 is a 40k+ 14 tpa mofo with neodym

the m120 is the same armature but with weak ferrite magnets

both are shit choices - the m140 is like a 18tpa or something 24/25k rpm motor

good all rounder

hearing that AliExpress cheapo shipments are over

where they slap a $2 toy on a £50 order to sail through customs

now they are adding the VAT/Duty to order to pay on your behalf or something

so getting very cheap motors from China & stuff may be over

the pic of motors wasn't to brag, but to show I foolishly bought the wrong m160 motors

from TinyWind/Airsoft Peak ages ago for like $16 with crazy coupons

bought a number of m160's & 4 x m120's & only 2x m140's

(fucking wish I knew better back then and just stocked up on m140's)

The M120 is too weak & too quick & M160 is a bit too fast & warm running imho

the m140 is the better of the 3 motors and advise people to play safe and go for m140 motor

 

[llure]

Hello guys!  

Think even US sites at say 400fps AEG with m120 would see PME risk start to creep in from say low to mid 30's

and if done correctly with decent shimming, airseal etc... on a UK spec gun 13:1 m160 11.1v he is looking at 45rps

just asking for trouble - even more so on an G&G ETU 

Sorry, I forgot to say... I'm from Spain, here the std limmitations are 350fps, many rof as you want.

In some fields, they ask for short burst and not use full auto as it is. But is not a regular rule.

that setup at say 350fps does 29/30rps aprox on 7.4v

The objective was arround 350fps on 30rps. That seem good for me, but maybe m160 add to much power consumption and heat.

With all the information above I can determinate that yes, is too much using the m160 xD.

I bought 2 for use in 2 simmilar builds ?‍

I can say: 13.1 gears, with m140 on 11.1V battery will be gtg on 350fps at 30rps?

I would like to run my std 11.1V battery on all my guns.

To do list:

- Buy a new fuse ?

- Test the original motor and a high torque one (guarder) and see what happens.

- Check the shim job again. 

 

[Davegolf]

It’s not quite as simple as just bolting ‘X’ parts together to achieve 30 RPS reliably.

You need to adjust AOE and short stroke it to prevent what has happened (PME) from happening again.

Like @Sitting Duck explained.

30 RPS is pointless IMO - accuracy and ammo consumption is crap.

20-24 is a usable rate of fire, and you don’t have to worry about PME.

Get a motor that turns around 18000rpm, run that with all your other parts and you’ll be sorted.

 

[Sitting Duck]

I can say: 13.1 gears, with m140 on 11.1V battery will be gtg on 350fps at 30rps?

I would like to run my std 11.1V battery on all my guns.

often the mid-range G&G's come with a 25k motor

if you're lucky the 25k IFRIT neodym or the 24/25k ferrite "Powerful Motor"

using a 25k motor, 13:1 gears SS 3 teeth on m120 spring you can get say 18~19rps on 7.4v

which on 11.1v will give you nigh on 30rps

The Short Stroke 3 teeth would reduce overspin & reduce risk of PME at higher speeds

If it is an ETU gun, then the ETU will cycle with some Active Breaking as well as fully complete cycle on semi

The issue is though the reliability of the ETU mosfet - if blown replace with Perun ETU mosfet than G&G

The ETU with moderate AB will lower overspin but at 30rps you sail close to risking PME

(you may get away with it, but at 30+ rps, a slight jam/misfeed and you will very likely get PME)

If you wasn't using stuff like ETU then at high twenties nudging 30rps on 11.1v

the idea would be to use a lower 7.4v to fire it a few times on semi at 19rps to park it better

then store the gun without spring compressed pre-cocked so to speak

A ROUGH ROF CALCULATOR...

for a 340~350 fps gun...

motor speed in XX,000 rpm divided by actual gear ratio.... x10

25,000rpm = 25k

25 / 13.5 (13:1 gear ratio) = 1.851851852

multiply by 10 = 18.51851852

so you can achieve around 18.5rps with a 25k motor & 13:1 gears aprox on a 7.4v LiPo

using a 11.1v LiPo you multiply the 7.4v figure by 1.55 (extra boost by extra cell)

so 18.51851852 x 1.55 = 28.7037037 rps expected figure

This is a ROUGH calculation if everything is built correctly, well shimmed and decent wiring deans etc...

but does kinda roughly establish a very rough expected figure for a 340~350 fps gun with a 300mm barrel say

(very short barrels require slightly heavier springs so will not follow or correlate to this quite so much

and much longer barrels require full stroke so not able to short stroke to avoid PME so have some limits)

But roughly works out within a few rps for most general builds on say a 300mm barrel or so

Your BD M160 is say a 40k 14 tpa motor...

40k / 13.5 = 2.962962963, x10 = 29.62962963 rps on 7.4v

then on 11.1v: 29.62962963 x 1.55 you was hitting  45.92592593

or 45/46 rps !!!!

even if not hitting this figure, but only say 90% - it's still 40rps

way too much

you could just run it on 7.4v & hit 29.62962963 rps

but the high speed M160 motor draws way too many amps

(anything over a 30k rpm motor is going to run warmer drawing more amps & not efficient)

The amp draw is a factor to consider as the higher it gets, the more heat & also

your battery drains quicker, with high speed motors going nuts spraying you will need to

change batteries before lunch on game days due to higher amps quickly depleting your LiPo

As @Davegolf has just said - 25 rps is a sensible max limit many of us have learnt the hard way

with a 25k Ifrit/Powerful G&G 13:1 you could achieve up to 29rps or maybe a bit less than max 29rps figure

say around 26rps using std wire & a smidge less if motor has carbon build up/a bit used

either a 30k motor on 7.4v, maybe 35k motor but it will run warm

or

a torquey 22k motor (22/13.5, x 10 = 16rps on 7.4v & 25rps on 11.1v)

this very rough calculation crap might help plan your next build a little better

(choosing the BD-M160, 13:1 on 11.1v was a big miscalculation if aiming for up to 30rps)

lower your rps to 25rps if you can build/shim well

or at least stick to the 30 figure and if you come out with say 26rps then be happy with it

I'd advise you look into short stroking if you want to run as quick as possible

to give you a little margin to avoid PME at higher speeds perhaps

Take the time to plan it all a little bit better and you will get closer to the figure you aim for

even in low 20's the gun is still snappy & responsive and a few rps once you get into the twenties

well you hardly notice if a gun shoots at 23rps or 26rps say

it is how well it cycles/shoots & sounds (and lasts) that really counts after that

 

[Davegolf]

Made a typo soz, cheapest and easiest setup is;

Same build as you have done already BUT use an 18000rpm motor.

 

[Sitting Duck]

Think 22k will be alright

if the Guarder Torque is somewhere between 18~22k

that might do it

18k might just get him into 20's

22k should get him into mid twenties just over

these figures could be squeezed a whisker more if everything was perfect

(and I mean nigh on everything close to perfect, perhaps bearings or mix of bushing/bearings

nigh on everything rolling ultra silky smooth, perfect motor height angle meshing, awesome airseals etc...)

thick wiring etc...

However a whisker off for std stock ETU wiring perhaps a bit more if ETU skims amp/rof

and if build not close to 101% perfection, slightly stronger spring compensating for meh airseal or short barrel

the rough calculation crap is just that - a rough ball park rof figure only

that you could be hitting 10% less or only say 5% above it if very very very fortunate/walk on water

(if people are a few rps shy of the figure - no biggy, it happens and only a rough estimation)

((if people manage to achieve a bit more - you lucky bastid))

 

[Davegolf]

I reckon an 18k would see around 22 RPS.

Which IMO sounds and performs excellent for a burst at a target in dense cover.

 

[Sitting Duck]

Yeah possibly 22rps

The calculation is a little under for good torque motors,

and a smidge over for much faster motors at times...

(I did say it was a rough ball park calculation)

There are other factors like a motor's max efficiency,

it's max possible speed - the 1.55 factor does not always apply,

wiring, MOSFET used, battery...

not all LiPo's perform the same,

You can get a standard lame gun to hit near 18 - 19rps on 11.1v

So yeah 22rps with 13:1 is achievable I concur

 

[Davegolf]

Apples and oranges ?

 

[llure]

Which IMO sounds and performs excellent for a burst at a target in dense cover.

Yeah, is the objective of this. My most visited fields (nearby) have high density of plants, branches and stuff like that make me use 0.25bb to break them all.  

I finally tryed the original motor from G&G. 18k rpm.

Do you hear anything weird? I only detect the spring and the piston head smashing against the cylinder head. 

I have to say that the motor was hot af before the testings. The wires were a little bit hot, but not so much.

What do you think?

I'm about to mount the barrel and test the rof.

 

[Davegolf]

That sounds pretty good, always hard to judge sound and colour on videos.

Sounds like you’re in the low 20s RPS ?

With the gears in the gearbox shell bolted up you should be able to spin them with you finger easily.

If you can see your pinion/bevel mesh, you should have full mesh, but not in to deep.

There should be a very small amount of backlash between them.

Other than that you need to make sure you have decent wiring gauge, 16awg.

Are you running active brake, that will be what is heating the motor most. Only on Semi auto.

Will run cooler on Auto.

It is good practice to drill air vents in the grip.

V2 gearboxes don’t have a nice heat sink motor cage like V3s

 

[Adolf Hamster]

Was it you or somebody else got a Big Dragon M140 cheap from AliExpress with coupons ???

Not me, i wanna say rogerborg?

Sorry, I forgot to say... I'm from Spain, here the std limmitations are 350fps, many rof as you want

Fair enough, in that case duck's advice is spot on- that rate of fire is way too fast.

Your risking serious reliability problems while still not keeping up with the hpa hoses.

 

[llure]

So I have been making some testings with the little monster and.. I have some news.

-The rof is 23-26 ish. I could say that is enough seeing how many bb fly over there ?.

-The plang sound is less audible once the gun is fully assembled. I keep hearing the cylinder head though.

-FPS question... I have mounted an Aliexpress 350mm(more or less) 6.01 inner barrel together with a madbull hop chamber and a blue bucking.

On 400 fps man.. How can I downgrade the thing? I added some images from the chrono.

Is a well known thing that G&G mount big springs due to the short size of the barrel. Using the same spring nowadays I'm over the limmit of my country.

A thing that I want to mention is that I had in mint to put some sorbo pad sticked in the cylinder head to reduce the noise. This might mitigate the FPS? Assuming that there's going to be less air in the cylinder.

-Assuming the problem with the 400fps, If you take a look on the values from the Chrono it goes from the 379 to 415fps. 36fps of difference. I must say that many of those rounds where fired on auto. Should I take only the measures on semi? Compression issue maybe?

Thanks for everything gurus! ?

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[Davegolf]

? Madbull barrel

Seriously the standard barrel will be better ?

Are you definitely testing FPS with 0.2s?
 

Your going to need to drop that spring rate down, no wonder the motor was getting hot!

Beware your RPS will increase again if you fit weaker spring.

Sorbo pad will be very useful, quieter, slightly lower FPS, and protect the gearbox.

Full auto FPS readings are never that accurate.

Test on Semi and you should have much more stable readings.