gears locking up

[Anonymous]

My gears have been locking up on my ak lately.  It's upgraded to 400 fps and after the gears would stop working I would disassemble the gun but leave the gearbox intact and I could stick a screwdriver into the gears and make them spin.  So I figured my motor was the problem.  New torque up motor and works good on simi auto but after a few mags on full it will lock up.  I know you all will say it's shiming, but I have messed with the shimming quite a bit.  So any other Ideas, or mabey a good shimming guide?

[Major Buttnuts]

I realize I didn't log in my name, so the question from above is me.

[gixser13]

what size battery? When they lockup recharge your battery or try another one. you should have atleast a 9.6 for upgraded AEGs
try this before we goto the next step

[Major Buttnuts]

I have had the gun for over 2 years upgraded to 400 fps useing a 8.4 volt 1700 mah and it's worked fine.  over the years I have decreased the spring then increased it back while adding a few upgraded internals, but never messed with the gears until the whole locking up issue.

[yellowmonkey]

Are your bushings still in good condition?

I also have this shim guide that Harley posted a long while ago:



Also, I'm not exactly sure if all gears are compatible with all pistons either, so maybe they aren't the same ratio or whatever.  :roll:

I'm just throwing ideas out there. Hope you get it fixed.

[Gantaliano Hoff]

It could be that, since you are running a lower level battery, the piston was just barely making it; and if the Piston has run out of grease or the grease it all dirty, it's not sliding smoothly. So the fact that your battery is a little low on power combined with the piston bot sliding correctly could be putting an adequate amount of resistnace on your gears and motor, therefore causing it to stop.

[busta_cap]

It could be that, since you are running a lower level battery, the piston was just barely making it; and if the Piston has run out of grease or the grease it all dirty, it's not sliding smoothly. So the fact that your battery is a little low on power combined with the piston bot sliding correctly could be putting an adequate amount of resistnace on your gears and motor, therefore causing it to stop.

I highly doubt that is happening, he would have to have alot of dirt in there too.. I have run a gearbox without lube for a while and it actually went pretty smoothly.. It's most likely the shimming was done incorrectly. Don't ever go right by the guide, do it to fit and feel.thats that best way.

[Major Buttnuts]

Ok, I can't figure out the correct feel for shimming.  I have read that there should be slight play in the gears side to side, and I have read that there should be no play side to side.  When my gun came upgraded from redwolf it seemed that there was slight play in the gears.

[yellowmonkey]

The little motor adjustment screw on the bottom of grip could just be too tight.

I'm sure you already checked it, but you never know.

[m-79_Grenadier]

Have you checked your wire placements in the grip?
There is a special position that the wires in the grip must go, or they will be too close with the motor, and cause it to actually stop working. This is actually very commonplace in the m16 series, especially if you havent had as much exeperience with dissasembling them. This is how to check it;
Make sure that both wires run on one side of the motor, which is usually the side towards the stock, and are not crossing eachother. Once you have the wires conected, push down on the back of the motor as if you were shoving it into the gearbox. The motor should easily be able to be pushed all the way down, and spring back up again without any binding. The way that the grip is designed is for the wires to barely have enough room between it and the motor. And the grip cap puts diagonal pressure on the motor for it to be aligned correctly, so if the wires are in the wrong place, its just going to tighten down on the wires, and have no room in the grip to move.

Ive had this unexpectedly happen to me at least three times. Usually the motor will work for a few shots, then it will sound like the battery is totally dead, because the wires are preventing the motor from turning.

[Major Buttnuts]

after investigation it seems to be the tight bore barrel creating suction on full auto.  It will fire a few rounds then stop shooting bb's, so I have to switch to simi auto and after two shots its shooting fine again.  Since it only locks up on full auto that seems to be it.