M4 help

[SeniorSpaz87]

Hello,

I'm going to try to take apart my M4 and diagnose the issue with its gearbox. The power is working, as my Madbull HUTU is working. It's most likely a stripped gear. Any advice is welcome.

First question, which I may figure out before a response is given;

How do you remove the gearbox from a G&P M4 body?

 

[AK47frizzle]

Some say not to open it cuz "WARRANTY RAGGLE FRAGGLE", but sack that, get some experience in tech work.

1st step, take off upper receiver and remove hop up chamber, then it should reveal the gearbox attached to the lower.

So to take it apart from the lower body, there are two pins on the lower receiver, one secures the upper (that one is at the front) and the other secures the gearbox (this one is at the back and it tougher to get out). What you need to do is get a hammer (yes, smashing time) and a screw driver; place the screw driver on the reverse side of the pin, and hammer the pin out.

Then remove the grip which is easy enough, few loose screws. Then there's the mag release which goes through the gearbox, push the button fully, then on the other side, rotate the pin (cw or acw, not sure) until it fully comes out, there should be a spring which might pop out so be careful.

Yank the fuker out and yer done. Do your tech work.

 

[SeniorSpaz87]

Haha friz, yea, I've opened it up before, but wasn't sure if I missed anything. Update soon.

 

[sp00n]

i take it the motor is turning?(making a sound), just no firing??

could be the motor has wound its self away from the bevel, or stripped its pinion gear :wacko:

take the top off then fire the gun, if the nozzle moves back and forth when fired, it likley to be a stripped piston.

if none of the above, then as you say, it sound like a stripped gear.

 

[Sitting Duck]

Google up some videos on opening ver 2 boxes......

One tip is a magnet under AR - ta Samurai, helps to keep Anti Reversal latch in place (esp when closing up box)

Would advise popping it in a plastic bag to catch the stuff as it explodes (more likely to happen if spring is halfway coked)

But very often the first time most of us opened up a box - $hit goes everywhere

(still sometimes does but not that often)

yup - do some pre checks before opening - the nozzle moving is a good sign gears are still turning

but piston can strip or even snap off the initial tooth....

motor height or even motor's gear can be stripped or came loose on shaft I have seen

there are number of things to go pear shape but it is just a load of nuts n bolts meccano set really

Clear a table that you can use for a few days - you may need to get a part or two

Take your time - watch a few videos, clean it, replace and ensure any parts are same size & operate really smoothly, no catching or binding

Take as much time as you need if you re-shim it - there is no race on shimming time - it is one of the most important things

when ya happy it all seems to work again - re grease & the fun bit, re assemble

(a couple of dry runs without spring to get used to closing up box is a good idea)

keep all screws n crap together or back in their holes or in a few pots etc.....

(times I've seen an ar spring just vapourise into thin air over night)

seriously if you take your time and using a little common sense it is not as hard as it sounds

it ain't easy at first attempt but like most things the more you have a go at it the more you will learn & gain

Besides - if it all goes bollox - you can either send it off or just say to hell and buy another v2 box anyway

There is a sticky about with loads of peoples tips on servicing gearbox's

well its somewhere on here with more hints n tips

http://www.airsoft-forums.co.uk/index.php/topic/19-gearboxes/

 

[SeniorSpaz87]

Actually, the thing is that I get nothing at all when I pull the trigger. The batteries are charged, and current is flowing (as the HUTU is on), but I get absolutely no movement or sound. I opened it up, reset all the gears, degreased and re-greased everything, and put it aside for the night. I need to re-solder some of the wires, so I'll do that in the morn and then put it all back together. Maybe it will work...

Actually, from the sound of it (or lack of), it could be the motor that's the problem...

 

[Sitting Duck]

sounds like it or rather doesn't make no sound at all

pull out motor - connect wires and it should jump/spin

if not the quite likely trigger wire has pulled off trigger

or something - or motor boned but very unlikely, but brushes do go at times

could be blown fuse even - deffo check that sod

all this crap is a process of elimination in the end

hence a good thing to have is a bit of common sense

and time - never just "think" oh its probably that and steam in

bloody hell - just listen to me - I am still boning guns so don't take everything I say as complete gospel

I still have so much to learn myself

 

[sp00n]

could be a burned out trigger if the motor doesn't spin as per SD's suggestion ... try a spare motor if you have one B)