M41A Problem AEG

[epic.d.works]

Hello. I have been having a problem with my AEG M4A1.

The problem: After shooting from 10 - 1000 rounds the "gearbox" or "motor" or something else seems to seize up. With battery charged, and a working mag. After pulling the trigger all I hear is a slight click as if the motor wants to spin but cant turn over. when pulling the motor down out from the handle it works fine.

When I take the gun apart and re-assemble it, It works for 10- 1000 rounds then I get the same problem. Jamb, or stuck or stubborn.

I have replaced the motor and the battery so far. and taken the gear box apart and re-greased it. not sure what to do next? can shimming help? and what does that require?

does anyone have another suggestion as to what my problem might be?

[Rusty Lugnuts]

questions - after it "seizes"
1. Does this happen only in semi auto mode? does flipping it to full auto help?
2. IF you wait an hour with the battery out does it start working again?

[Mandalore]

What battery are you using?

[MaciekA]

Could you explain what you mean by "10 - 1000" rounds? Do you mean that sometimes it fails after 10 but sometimes it fails after 1000?

My advice for a gun that doesn't want to turn over is to investigate every subsystem in the gearbox and ensure that you have free movement:

• binding of piston against cylinder or cylinder rails
• binding of sector against the piston (sector gear too big/piston too low)
• binding of gears against other gears (crappy shimming or mismatched gears)
• excess friction in shimming (too much shimming)
• broken bearings (wobbly)
• bushing holes in gearbox shell have been "enlarged" after excess use due to wobbling bearings (elliptical movement from steel bearings gradually opening up a larger hole in an aluminum or pot metal gearbox shell, lack of contact adhesive to hold bearings will cause this).
• broken/cracked/wobbly shaft on anti-reversal latch.
• broken/cracked/wobbly shafts on gears
• excess friction between sector gear and cutoff lever
• excess friction between sector gear and tappet plate
• tappet plate unable to move freely, bent, broken, etc

Other things that could be causing this:

• Your battery may have sucked. You MAY have replaced it with another sucky battery (hey, it's possible!). If in doubt about the battery, get a "reference" battery (for testing) from hobbyking with like 4000mAh+ and 30C+ and you will always be sure *that* isn't the issue. Too many of these posts essentially boil down to people mixing a crappy NiMH with a M140 spring or something of that sort.
• Your wiring perhaps has a pinch or other issue that only exhibits itself after some use or heat-up.
• Your trigger contacts have finally accumulated too much material on them to power the gearbox after some moderate use.

Re-greasing the gearbox won't help you here. If it were my gearbox I'd carefully rebuild each part of the system and test as I went.

[Rusty Lugnuts]

Could be the semi auto glitch

[epic.d.works]

wow.. thanks guys.. going to investigate.

-Re: semi vs full auto. I always play in semi. so it happens in semi. but switching it to full has only fixed the problem once or twice out of the 20 times I have had this problem.

- And yes. when I wait or change the battery it seems to work again... sometimes. other times I need to pull gun apart and gearbox and build it again, not changing anything and it works

-as far as 10-1000 rounds, yes sometimes 10 rounds, sometimes 1000
-I'm using a G and P 1600 mAh 1.2v nun chuck

MacieKA- Allot of the "wobble of gears and looseness could be a problem at this point from how many times I have taken it apart. but I am going to rule it out due this being a problem before I took it apart.

-trigger contacts are fine
- wiring seems fine I have done continuity testing while bending every inch of the wire harness.

My guess is either piston is not moving or the gear that moves the piston is out of sort. As far as shimming goes in a gearbox, I have no Idea what I'm looking for. all barring's seem ok and all pins and springs are in place.

my other guess would be the gearbox its self. would you recommend me trying to fix this or just buy a new box? .. p.s. don't want to spend the cash at the moment

thanks for the input guys... keep them coming I must be getting close.

[ThunderCactus]

Try using a different brand, like elite
G&P is very well known for having dud cells in their batteries.
Could very well be a cell is dying out erradically

[Hectic]

i vote battery also, seccond vote is for something too tight most likely battery tho
last guesz is somethi.g ive only had happen once, cracked gearbox at the front where the piston hits the cylender head

[epic.d.works]

ok., out to get new battery. thanks guys.. ill see how it goes

[venture]

If that doesn't fix it then a new motor is your next step.

[ThunderCactus]

Actually, have you ever set you motor height since swapping to a new motor?

[m102404]

1. Try a known good large battery (or equivalent). You don't specify what your motor/gear ratio/spring is...but if it's a typical setup any good fully charged large (sub-C cell size) 8.4V 2000+ mah battery should be able to crank it. Borrow a buddy's battery or get one (they're handy for testing/building/etc...). A good 11.1V 1100+mah 15-20C battery should do it too (at least for testing).

if you get the click/clunk

2. Reset your motor height. Turn it in and then incrementally turn it out until you get the least amount of screeching.

3. Consider swapping the switch, trigger, motor. You may have a break in one of the wires that may not show up until things vibrate/heat up. You may not be getting enough power through your switch contacts/switch block. I say trigger because some triggers work better with some switches...the tips of some triggers are so misshapen it's a wonder that they work at all.

Best of luck

[suzenonest]

I'm guessing its a combination of too strong of a spring and weak battery