TM/G&P M4A1 Gearbox Problem...
 

I test shot my M4 today, and it was working great until after about 20 shots. After the 20 shots it stopped responding. I opened it up to realize the fuse had blown out.

I went to Canadian Tire and bought a replacement, when I tried it, it still did not work.

I opened it all up, tested it with just the motor, and the motor works....

I then went to mechbox tutorial thing, and opened up my gearbox.... Nothing seemed to be broken, although it was a pain in the ass to put back together...

So from what I can see, the motor is no longer able to turn the gears anymore?

It is a G&P m120 motor, using a 9.6v battery (tried a king arms and a mach1).

not too sure about the spring, but it was supposed to shoot at 380fps.

The original fuse was a 20Amp
I bought a pack of 25 and a pack of 20, both work with the motor, but the gears seem to refuse to move...


*could it be the motor dying?*

BTW the trigger locking pin fits ok, but at the end where it has like a grip/spikes coming out it's like impossible to put back in, any special technique?

Some pics, the gears are turn really smooth...
http://jiabun.com/images/gb.JPG
http://jiabun.com/images/gb1.JPG
http://jiabun.com/images/gb2.JPG
http://jiabun.com/images/gb3.JPG

Your wires are chewed up so you may be having a short.
What are the details on your battery? Just saying 9.6v doesn't mean much. Small, large, type of cells?

They are the King Arms 9.6V 1600mah mini battery from airsoftparts

and the Mach1 Airsoft 9.6V 1400mah mini battery

Motor works ok, but once i put the pistol grip on, and tighten the screw that brings the motor inside to touch with the gears, the motor doesn't seem to have enough power to turn?

So I should buy some new wires to replace the old ones?

And regarding the locking pins, am I supposed to hammer it in? It won't go past the grooves near the end... Or should I just give it alot of lube...

Gonna go to my first game a little more than a week from now, so was hoping I could fix it by then.... Otherwise do you think I should just go to velocity arms and buy: http://torontoairsoft.com/product.php?id_product=62

Yeah you can get new wires, or get a gundoctor to solder on a new length of wire and repair it if you can't do it yourself.

I'm thinking electrical short. Or the motor is too high, or your box is shimmed too tight.

So um I took another picture, it doesn't seem like it has completely chewed through, I will wrap it up, and double check the shimming... as it may be too tight.... It was working no problem before though, and only screwed up after the fuse blew... T.T

http://jiabun.com/images/wire.JPG


And regards to the locking pin for the trigger....

Any idea how one usually gets it in? I got it out easily haha, but I tried just with an empty shell, and I can't seem to get the grooves to get into the hole....
http://jiabun.com/images/pin.JPG


*I just re-adjusted the shimming gonna try it again after dinner :D*

For the small locking pin, put the smooth end in first then just lightly tap it in with the end of a screwdriver. Even though your wire isn't completely chewed through, I'd still replace it with a new one. If your wires are getting chewed like that, it mean that when the MB is closed, the wires are sticking up and your pinion gear or bevel gear is chewing on it. When closing the MB, make sure the wires are not touching or sticking up in any way. Good luck.

Hm, I think it really is the wire problem haha... Time to get new wires >.>

For the locking pin, no matter how I tap it, it still won't go in T.T


The battery get's really hot!, you can hear the motor try and move the gears but it can't... So it is either a shimming, or a wiring issue T.T

Might have to start hunting for a gun doctor lol...

When you're tapping in the pin, don't have anything else screwed on (mag release, rear pin). This way you'll have some movement to put the MB in place to tap in the pin. Give that a try, that's how I do it.

anyone else notice there's no grease in there?
no grease, no sealing, no performance!
assemble the gun in this order:
rear body pin, mechbox pin, buffer tube, grip

No grease in where? We can only see the gears, nothing really about the compression parts.

o.o well I wiped the wire clean, and wrapped it in electrical tape....

I played around with the shims, I think it was too tight also and now it's working perfectly :D

I will have to get some grease as I probably wiped some away with my hands with all that playing :D...

Gonna have to get some new wires for sure when I get the chance....

I'll have to shoot it in the basement tomorrow when I get home late at night lol @.@

bring the mechbox by my place and I'll fix it up.

can't shoot at my game without a rifle...:)

It's working now :D Gonna test fire a bb either tonight after I finish some work or tomorrow after my classes hehe...

Hoping Jugglez is available on Friday, so I can go and pick up some wires/extra shims, and I planned on getting a weaker spring anyways so I can use the gun in indoor games...

Probably will pick up an extra mag for myself lol....

If it continues to have problems, I'll see if you have time to look at it for sure!

*update*

So I re-soldered all the wires, changed all the wires out and stuff... reshimmed it

Works nice on my King Arms 9.6V 1600 mah mini battery

The motor isn't strong enough to turn with the Mach1Airsoft 9.6v 1400 mah mini battery. However, I will charge it in case it is low... and see :D

You're shimming is clearly too tight if you can't pull a 380 spring with a 9.6. With a G&P M120 motor, you should be able to pull it with 8.4v

Take out a few shims. Shimming is better slightly looser than tighter, gives it room for tolerance and ease of rotation.