Gearbox Help Please!

[Atomic]

I need some help with my gearbox. I have a TM M16A2. Last year I put an M100 spring and metal bushings into it. I have played with it twice since then and fired multiple mags through it with no problem. Fo some reason, the black air nozzle that normally is forward is stuck in the retracted position, so the gun will not feed in semi-auto.

I broke the gearbox down and reset all of the gears. I did not see any damage to any of the gears when I did so. The problem is still there. It works properly in auto, but the air nozzle (and tappet) stays in the rear position in semi-auto.

I broke the box down a second time with the nozzle retracted, and the gear with the post that pulls the tappet plate rearward is now in the 7 O-clock position. I aligned it in the 1 o'clock position when I put it together.

Any advice would be appreciated. I am a do-it-yourselfer, but unless I can get some real advice, I will have to let the pros take a look at it.

Thanks

[Dutton]

Any chance you could post a picture of the gearbox as it is now?

[Steamer]

Hmm...

So when you, look down the mag well in full auto the nozzle moves, but while watching in semi it doesnt?

I'm doubting that, it would have to cycle. You could be misdiagnosing a feed problem.

[Atomic]

I need some real help here. The air nozzle cycles every time. In full auto mode, it returns to the correct position (forward) at the end of the cycle. In semi auto, it stays locked in the rear position at the end of the cycle, causing feed jams.

I got to the point of tearing down the mech box after I troubleshooted the magazines, hop up, etc. The air nozzle is out of timing in semi auto. I need advice from someone who knows exactly what it the problem is, or can give me some advice.

Thanks.

[Steamer]

You are getting double feeds in semi? Just trying to under stand the affect, then help with the cause.

[Atomic]

Originally posted by Steamer
You are getting double feeds in semi? Just trying to under stand the affect, then help with the cause.

It isn't feeding at all in semi, after the first round. Then it doesn't feed at all.

The crux of the problem is that the air nozzle is staying in the retracted position at the end of the semiauto cycle. It doesn't do this in full auto.

[BlackHawk97]

http://i46.photobucket.com/albums/f121/Black97Hawk/Guns/normal_ICSM4Review10.jpg
Hope this helps, I figured it may help. And steamer I know that you know what the tappet and everything do, I just wrote the stuff in there for those who don't.

[Steamer]

Originally posted by Atomic
the air nozzle is staying in the retracted position at the end of the semiauto cycle. It doesn't do this in full auto.

The trouble I am having with associating this with a feed problem is, if your semi is finishing the cycle with the nozzle retracted that isnt really a problem. It doesnt matter where it ends in the cycle, its still cycling(asking the mag for a BB).

[Steamer]

Originally posted by Atomic


I got to the point of tearing down the mech box after I troubleshooted the magazines, hop up, etc. The air nozzle is out of timing in semi auto. I need advice from someone who knows exactly what it the problem is, or can give me some advice.

Thanks.

The "timing" isnt the issue, its the same for both full/semi.

"Timing" the gears isnt really a concern, and if you want to do it right, the anti-reversal should be engaged with the sector gear tappet nub at the 1 o'clock position.

The Sector gear tappet nub can only be placed from the 1-3:30 before it, or the "sector teeth" will start to interfere with other parts during installation. This envelope is safe for "timing".

[Atomic]

Thanks blackhawk, that is exactly what is going on. The nozzle is supposed to retract during the cycle. allow one BB to feed, spring forward, and then the piston slams forward, expelling the BB.

In my case, the air nozzle does all of this, but then retracts again, causing the weapon to jam when multiple BBs enter. It isn't double feeding, it is jamming.

I have it apart again. I think that the problem is electrical and that the motor is not getting the signal to stop in semi auto, until it is 1/2 a revolution from the 1 o'clock.

I appreciate all of your help.

[Atomic]

Originally posted by Steamer
The "timing" isnt the issue, its the same for both full/semi.

"Timing" the gears isnt really a concern, and if you want to do it right, the anti-reversal should be engaged with the sector gear tappet nub at the 1 o'clock position.

The Sector gear tappet nub can only be placed from the 1-3:30 before it, or the "sector teeth" will start to interfere with other parts during installation. This envelope is safe for "timing".

Thanks. When I talked about the timing being an issue, I was looking at the overall picture; the gears are in time, but something isn't. The motor doesn't stop turning when it should, leaving the tappet plate in the retracted position instead of the forward postion at the end of a cycle.

I have expended my abilities on it, so I am getting ready to hand it off to someone else.

Thanks alot for your help.

[Steamer]

Sorry, double post

[Steamer]

Originally posted by Atomic
Thanks. When I talked about the timing being an issue, I was looking at the overall picture; the gears are in time, but something isn't. The motor doesn't stop turning when it should, leaving the tappet plate in the retracted position instead of the forward postion at the end of a cycle.

Again not really an issue, this can be a result of a number of things, none of which relate to your problem.

I feel it is a feed issue, try holding your mag up in the mag well, rock it forward, backward, even hold the gun upside down while firing.

Lube all points of interest, mag, feed tube, hopup unit/bucking.

The Bucking does 2 jobs when installed correctly. When a BB is pushed up the feed tube it will rest at the mouth of the Bucking, and wait for the nozzle to push it past the mouth, then rest at the bucking/nubbin that is pushed through the flute in the barrel by your hop up arm. It then waits for the piston to release. Air then pushes it out the barrel with some back spin that the bucking/nubbin imparts.

If you are getting multiple BB's in the chamber, your bucking(mouth) could be torn, worn, or installed incorrectly. Recheck your bucking. Turn off your hop up, place a BB in the Hop up/barrel assembly, and see if it rolls out, if it does try reinstalling the bucking, or purchase a new one.


(Timing the gears is a myth, its self timing. As long as you are not engaging any sector teeth with the piston during assembly, it will self time, hence the 1 o'clock position for the sector tappet post)

[D_Man]

I'm with Steamer here, your nozzle is working properly.

Sounds to me it could be a hop-up problem or a mag problem.

[Steamer]

Atomic,

What BB's do you use?

[Atomic]

Well, everybody else was right and me wrong. There was nothing wrong with the gearbox, and it was working properly. I dropped the gun off at AirsoftSmith who took everything apart and rebuilt the hopup. Afterwards it worked. No parts replaced, just something misaligned in the hopup (evidently).

Thank you for being "real help" even though I was too stubborn to listen.

[Steamer]

;)