Help With V2 Gearbox

[steve1462]

Hi guys,

My first gun (used) G&G CM16 Mod 0 (30 anniversary) died a while back and never got round to sorting it.

Due to having all this time I've taken it apart and found it the trigger switch contacts that are worn (guess from using lipo batteries without a mosfet in it).

I've installed a cheap mosfet with new trigger contacts and put it back together  hooray the rifle works again!

Only problem is after shooting on auto, when I take my finger off the trigger there is a sound a bit like high speed unwinding from the gearbox. Ia this the anti-reversal latch? Have I installed it wrong?

Any help would be appreciated

View attachment 58599

 

[Sitting Duck]

very likely the anti reversal latch binding

(if installed correctly)

did you mess with anything else ???

did the ARL break - had one & only one break on me & it was a G&G one with the nicks in it...

after that I often replace them with a more common ARL

which is less chunky especially at rear on shaft just above the latch arm itself

*** next bit does NOT apply to your gun as it is front wired, but on rear wired G&G's... ***

The G&G boxes for some fucking reason have the ARL hole mounted very close to wiring channel

if you have added thicker wire - say 16awg silicone - well this is really thick shit and struggles to get into the channels

G&G ARL broke on me where those nicks either side are and when upgrading others that thick shoulder rubs on rear wiring, time you add thicker wire that squeezes into thin channel at back (not in your case as it's front wired)

So coz the only ARL breakage was a G&G & coz it is so chunky I replace them where possible coz they're shit imho

back to your gun, it is front wired so wires binding on the ARL is not an issue...

It is either broke, or the way it was mounted, the spring slipped off, or somehow binding

that the ARL is not returning to latch onto the 5 lugs on the std G&G bevel gear

(so it bounced but is not returning to lock the drivechain properly or quickly enough)

it does not need to be insanely tense but a mere moderate tension to relatch in use

something somehow has gone tits up on the ARL like you determined yourself (well done)

so alas you gotta rip it open & investigate how the ARL & its spring is operating effectively

the spring could have broken, slipped off most likely if refitted properly (it happens like trigger spring can break)

you "might" need to consider a spare one or buy a spring set if that pubic hair spring has snapped or not sitting correctly

https://www.ak2m4.co.uk/internal-parts/misc-internal-parts/zci-anti-reversal-latch-v2-v3

but yeah gonna have to open her back up again to check what is up with ARL I'm afraid

 

[Zarrin]

I think some shells possibly have enough space for the AR latch to be installed upside down; if that is the case you would have the curved side of the AR latch trying to catch the grooves on the bevel gear - i.e. it wouldn't work and the spring would just unwind after every shot - the AR latch arm might also be sitting too high above the bevel gear grooves in this scenario.

Alternatively you could have installed the AR latch with the arm resting in the 1 o'clock position which would have it riding over the top of the bevel gear. you need to engage it with the bevel notches by manipulating it into approximately the 4 o'clock position and then testing that it works by rotating the bevel gear to make sure it is catching on the AR lever arm.

 

[steve1462]

Thanks for the help guys, it's my first time opening up the gearbox so it was a little new to me so just took it slowly and tried to be methodical after watching loads of youtube vids!

I've opened up the box again and yeh, I hadn't installed the ARL spring properly; sorted that out put it back together and no more gearbox spinning after a shot.

I do have another issue though - when I shoot of full auto, the trigger returns to position properly but when I shot semi, the trigger stays pulled in and i have to manually push it forward to engage for the next shot.

Any ideas?

I initially thought maybe the trigger caught on a wire from the new Mosfet, but surely that would do it in full auto aswell as semi?!?

I've recorded a video to show it.

Again, any help is appreciated!

View attachment 58608

 

[Sitting Duck]

Trigger spring missing or broken is most likely....

hook bit goes through eyelet on trigger, then slips into place

it can try to jump out of box, you can add a dab of glue/epoxy to the spring on trigger axle

which helps to keep attached to trigger and assists in it not jumping out quite so much

the trigger spring if broken will need replacing

the ZCI v2 spring set includes a trigger spring £4

https://www.ak2m4.co.uk/internal-parts/misc-internal-parts/zci-gearbox-spring-set-v2

where as the SHS set does not @ £3

https://www.ak2m4.co.uk/internal-parts/misc-internal-parts/ra-spring-set-v2

at least you are gaining experience opening & closing the gearbox

(for what it's worth my first few boxes didn't go well, first couple went in the bin, so you ain't doing that bad in my book)

 

[steve1462]

Thanks buddy.

Took it apart, removed the trigger and cleaned it all up put it back together and its fine after that!

However, it has now just popped two fuses in a row after a couple of shots. Taken the gearbox apart and looks like the contacts on the Mosfet I bought (Jeftron) are rubbing on something and shorting out.

Maybe that will teach me for buying a cheap mosfet! Back to the drawing board....

 

[Sitting Duck]

check motor height & also check the wires at motor are properly insulated

(they can short if they touch the metal motor plate at bottom of grip)

check wires throughout loom have no breaks on insulation

especially where they pass through gearbox front/hop unit into front of receiver

if they are still inline connectors, to assist removal etc... ensure they are properly insulated

by looks of it, you got black red main power leads with a blue signal/trigger wire running to a mosfet

so it is a straight forward mosfet using existing wiring maybe, with red posi wires now on one side of switch

then blue wire running back to mosfet as signal/trigger wire to activate the mosfet

it is not the mosfet - but a wiring issue/electric short or your motor is a bit high or shimming a bit out

causing a large draw in amps that will blow the fuse

a cheap shit mosfet like APS/Big Dragon switch with wiring - now THAT is shit

using cheap 1404's mosfets than 3034's - plus I'd say the 1404's are fakes anyway

THIS is a shit mosfet....

or

the ones with an inbuilt blade fuse, looks like a clever mosfet but they are cheap shit (likely snide) 1404's

(a GENUINE 1404 is a bit lame but should be OK for most stock/mild guns)

Those shite snide mosfets blow as soon as you fart near them

your mosfet is still working, so it "should" be OK, it is either wiring or motor/shimming causing large amp draw that blows fuses

 

[steve1462]

So one of the contacts on the mosfet was really badly soldered, and it looks like it was earthing out on the fire selector switch (or whatever the switch if that changes shooting mode between safe / semi / auto)

i took that connection off and resoldered some slightly thinner wire and the switch now clears the solder. Hopefully this ends all the troubles.. now to order some mini fuses before I can test it1

Whilst all this has been a pain in the ass, I must admit its taken all of the fear out of opening the geabox or doing upgrades.

Thanks for all the help

 

[Sitting Duck]

Well it seemed like you have a separate mosfet, likely located in hand guard

than an internal mosfet switch type (they do a range of stuff from basic, AB right up to Leviathan)

What you need to be careful of on V2's is how the wires go to motor from switch

I've poorly routed the wires from switch and punctured them with the receiver pin when refitting into receiver

So all these errors and fuck ups are a good way to learn from our mistakes = wisdom

You just need to pay attention in how the wires are positioned & soldered at switch area

(fucking PITA when you are still finding your feet, but you learn from your mistakes as explained)

THIS sums up a great many things as we stumble our way through life....