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G&P M4 Gears not turning

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Hi, not entirely sure why it is not firing, not sure if it is a gearbox or motor issue. I have had the gearbox open a few times and everything is in order and it reassembled fine. I have just got a new battery in to day (7.4v 1300Mah LiPo) yet it is still not cycling and I am not entirely sure what the issue is. I made a quick video of me attempting to fire it in the hope it will help someone to help me, the sound you hear is the motor not the trigger I believe.

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You can't even hear the sound of the motor turning, which is what should happen when you apply the trigger mechanism, it sounds like it is clicking back.

 

Regarding the motor, has it ever made the standard whirring noise when firing?

 

Have you made sure the power lines to the motor are still in contact?

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I think what's happening is you've connected the motor contacts the wrong way round, so it's actually trying to spin backwards but it's being stopped by the anti reversal latch.

 

I've had that experience many times.... Just make sure you hook up the positives and negatives the right way round.

 

If that's not it then i dunno

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You can't even hear the sound of the motor turning, which is what should happen when you apply the trigger mechanism, it sounds like it is clicking back.

 

Regarding the motor, has it ever made the standard whirring noise when firing?

 

Have you made sure the power lines to the motor are still in contact?

 

Yeah, the power lines are 100% connected I can hear the motor engaging in the pistol grip.

 

I think what's happening is you've connected the motor contacts the wrong way round, so it's actually trying to spin backwards but it's being stopped by the anti reversal latch.

 

I've had that experience many times.... Just make sure you hook up the positives and negatives the right way round.

 

I will try changing them over and see if that makes a difference but i think I have tried that.

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Ok, update - Flipped the motor round so I could change over the connections and that worked however now my piston is stuck all the way back but my air nozzle is is not pulled back?

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Is it a changeable motor depth?

 

I don't know what it's actually called, but in the bottom of some grips, there is a pressure screw that pushes the motor closer to the gears, it may be in too far?

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Is it a changeable motor depth?

 

I don't know what it's actually called, but in the bottom of some grips, there is a pressure screw that pushes the motor closer to the gears, it may be in too far?

 

Yeah, tried adjusting the motor height and it will either spin as though it is not connected to the gear as it will be too high or it will make a similar noise to before and not do anything. I am not sure why it hasn't pulled the piston back.

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You say you've pulled the gears apart before,

 

Maybe the gear is no longer aligned in the box to pull the piston back out.

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Potentially, I wanted to avoid pulling it apart again as I have V2 Gearboxes but i suppose it must be done haha. Cheers for the help guys will take another look inside and see what is up.

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Is the piston still locked back?

If so try disabling the anti reversal latch through the motor goes through.

If that doesnt work, then be very careful opening the box as it will be under loads of tension due to a compressed spring

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Is the piston still locked back?

If so try disabling the anti reversal latch through the motor goes through.

If that doesnt work, then be very careful opening the box as it will be under loads of tension due to a compressed spring

 

Just took it apart and as soon as i lifted up the half of the gearbox the spring released so Something is catching just not sure what.

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Update - Been testing and it will do one cycle and about a half, then when i pull the trigger the next time it will finish the half rotation but not spring back and then it is stuck like that until I open up the gearbox and release it. Does anyone have any ideas as to why it might do this?

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The only time mine did that the piston was not lined up on its runner properly and was twisting as it went back.

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The only time mine did that the piston was not lined up on its runner properly and was twisting as it went back.

 

Hmm, it does not look like it as I can see it is in what looks like the correct position, I will do a video tomorrow night and hopefully it will shed some light on it

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The only time mine did that the piston was not lined up on its runner properly and was twisting as it went back.

It has happened to me before when I first attempted shimming and I shimmed it way too tight so that the gears only brought the piston part way back before jamming.

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You need to go through a process of elimiation.

 

1) Take out the spring, piston, cylinder/head, tappet and AR latch, screw back together. Use a small screw driver or similar to spin the gears (go in through the cylinder window and spin the sector gear). They should spin freely and keep spinning after you flick them with your screw driver. If they dont move or are hard to move or dont spin freely - your shimming is too tight.

2) Check your motor alignment in relation to the bevel gear and the spacing between the two - this is really important to get right. Test this with just the gears and the motor and grip installed. A "screechy" gearbox when fired on full auto will reveal issues with the motor alignment and shimming.

 

If all is ok after doing those, then move on to testing with the piston etc installed.

 

There are loads of good tutorials on youtube for shimming etc: https://www.youtube.com/user/AirsoftingTutorials/videos

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