Ver. 2 Gearbox Issues: M4 Semi not working, Gears locking
shelcoof
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Post: #1

Hey folks

Alright well I've always had bad luck with Airsoft AEGs...version 2 gearboxes hate me.
I find when I try to fix one problem I am presented with another then followed by more problems and it never STOPS!!!!

Alright well current situation is that my Gearbox I'm working on now is giving me either three issues (there are tons more problems but these are usually the end results)

1. Gearbox fires in full auto only
or
2. Gearbox fires full auto with the very rare occasion semi and even then I'll have to pull the trigger twice on semi and it will be rare to have semi work
or
3. Gearbox locks up... the piston will be pulled back but will not be able to snap forward

Most common right now is full auto or piston locking back.

Things I've done to try and diagnose the problem

- Used 2 different springs equivalent to an M100 and an M110
- Tried 3 different cut off levers
- Two different Pistons
- Tried 3 Selector Plates (I broke 2! of them)
- Tried 3 Sets of gears (Original G&P, SRC, JG gear sets)
- 2 Triggers
- Mix and matching 3 Safety levers
- Used two Trigger Assembly (G&P original trigger assembly, SRC trigger Assembly)
- 2 motors (G&P, SRC)
- Used many batteries mainly buffer tube stick lipo batteries

Things I've checked
- Re-shimming gears to make sure they are spinning smoothly
Though I did notice there is a bit of play with the gear that makes contact with the motor pinion. Other than that everything is smooth... I think

- Check to make sure gear makes contact with the cut off lever.
- Made sure cut off lever made contact with the trigger assembly. However I have no idea whether or not if it makes proper contact

- Spring connecting Selector plate and cut of lever is working
- Cut off lever is moving smoothly and freely

Anyways I've had enough headache for several days now.
It all started with swapping out for a longer barrel.
Then the FPS exceeded 400fps.
Did a spring swap, find out selector plate broke where the spring connects the to the cut off lever.
Tried swapping out the selector plate with a brand new one without opening the gearbox failed snapped the selector plate
Opened the Gearbox and installed the selector plate success
Reassembled and tested.. something wrong with the safety lever.. its locking up
Open to check the problem then snapping another selector plate in the process of removing the gearbox
Curses non stop but then manages to find another spare selector plate..
Has glimmer of hope
Opens up gearbox and installs the selector plate
Reassembles and gets it shooting under 400fps
Thinks I'm done but wait... trigger no longer responds
Need to open up the gearbox again and finds trigger assembly has come loose
Re-align trigger assembly then puts everything back together
Tests again and its shooting... then same issue occurs
Opens up gearbox again and finds trigger assembly had come loose again
Inspects further and finds the part where the screw holds down the trigger assembly had been stripped. No idea why this happened as it was the 2nd time I've ever opened the gearbox.... probably issue from previous owner
Scraps the SRC Gearbox
Opens up brand new G&P complete gearbox to install
Installs this new baby to find new problem. Oh no.... the gearbox locks up and piston is retracted completely
Opens up to reset the gears
Install and shoot to find it locking up again
Do this several times then decides to try out different piston Fail Locks up
Tries to downgrade spring Fail Full auto only now
Tries out SRC Gears Fail Full auto only now
Tries out SRC Trigger Assembly Fail Safety lever locks up
Swaps out Safety Lever Success does not lock up but now Full Auto still
Tries out brand new JG Gears Locks up and shoots full auto
Swaps out the semi/full auto levers locks up and full auto
and...... I end up doing a combination of different parts and still nothing but the three things listed there

Sooo... anyone have any ideas?

Appreciate any help
Cheers
S
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lurkingknight
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Post: #2

what piston is in the gearbox?

I futz with v2s, v3s and v6s
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shelcoof
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Post: #3

As of right now G&P stock piston
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lurkingknight
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Post: #4

when you get it to the point of full auto in semi, it's a worn cutoff lever or the cutoff lever is not resetting the trigger shuttle.

edit: or you have too many shims on the cutoff side of the sector gear.

I futz with v2s, v3s and v6s
(This post was last modified: 07-06-2013 01:53 PM by lurkingknight.)
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shelcoof
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Post: #5

I swapped out the cut off lever with a known working one and still locks up or shoots full auto

I inspected all the levers and they all look the same all three.

I also have two trigger shuttles one brand new and one used that was previously working as well and still no dice.

The cut off lever does not have any shims and is moving freely.... however I probably should inspect the gear that makes contact with it though but I don't think I've over shimmed it though.
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Teach Russ
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Post: #6

fire select issues: can be has simple as a worn return spring on the selector plate.

piston jamming: Shimm can be too tight. I've seen a bad piston jam in a V2 dboy using a G&P 120 solved by swapping the G&P motor for a high torque motor.

Good luck

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(This post was last modified: 07-06-2013 02:10 PM by Teach Russ.)
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shelcoof
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Post: #7

I have a few cut off lever return springs and actually have used 2. The first time I pulled it off it flew out and well is now gone lol
but I guess at this point I'm pretty desperate... I guess I'll try another
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vondnik
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Post: #8

Just a note to all for the cut off lever spring: it's the same thin as in a bick lighter....... 1 lighter will cover 2-3 guns.......

Nothing is impossible for the man that does not have to do it himself
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shelcoof
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Post: #9

thanks vondnik for the info
I lose springs all the time for my toys lol
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Reaper
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Post: #10

what is the ratio of your gearset...do you have fuse...also check wire for no pinch or broken wire inside the insulation ... try whit diff m4 handle ... if the handle make motor to close to the bevel gear it will give you hard time on semi... maybe the adj screw push down the motor and doenst give enough adj range or the way the handle was built...it happen a lot whit aftermarket handle...try whit original handle as for exemple...what u can do is install the handle on gear box before put gearbox into the body and install the motor aswell...it will be faster to diagnose whitout take everything appart again and again

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shelcoof
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Post: #11

Yo Reaper: I don't know what the ratio is... though I would assume the stock G&P gears should work properly on the stocked gearbox.

Wires were all fine no fuse was used... though currently due to my lack of improperly closing up the gearbox the wires have been pinched by the motor.

I've checked motor height and made sure it was not too tight... I'm pretty sure its not the motor.
I did try that many times before just screwing on the pistol grip instead of putting everything back into the lower reciever as that saved me a ton of time doing my trials and errors.

But hey I'll give the stock pistol grip a shot and see if that will work.. doubt it but will at least try it.

Thanks for posting.
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Reaper
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Post: #12

(07-07-2013 09:54 AM)shelcoof Wrote:  Yo Reaper: I don't know what the ratio is... though I would assume the stock G&P gears should work properly on the stocked gearbox.

Wires were all fine no fuse was used... though currently due to my lack of improperly closing up the gearbox the wires have been pinched by the motor.

I've checked motor height and made sure it was not too tight... I'm pretty sure its not the motor.
I did try that many times before just screwing on the pistol grip instead of putting everything back into the lower reciever as that saved me a ton of time doing my trials and errors.

But hey I'll give the stock pistol grip a shot and see if that will work.. doubt it but will at least try it.

Thanks for posting.

no problem give.. try it it happen me couple time ... maybe is not that but so simple it can work lol just let me know what happen

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lurkingknight
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Post: #13

you'd be able to hear if the motor was too high or low.

If the piston is jamming midcycle and there's no sign of binding on the piston, your shimming may be too tight.

pull the piston/spring and arl out and screw your gearbox shell back together and test the gears. gears on bushings should turn 3-4 times, bearings they will turn for a lot more.

with the gearbox shell screwed together you should be able to get a tiny bit of side to side movement out of the gears, maybe a sheet of paper or so if you pry at them very lightly.

I futz with v2s, v3s and v6s
(This post was last modified: 07-08-2013 01:00 PM by lurkingknight.)
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shelcoof
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Post: #14

(07-08-2013 12:59 PM)lurkingknight Wrote:  you'd be able to hear if the motor was too high or low.

If the piston is jamming midcycle and there's no sign of binding on the piston, your shimming may be too tight.

pull the piston/spring and arl out and screw your gearbox shell back together and test the gears. gears on bushings should turn 3-4 times, bearings they will turn for a lot more.

with the gearbox shell screwed together you should be able to get a tiny bit of side to side movement out of the gears, maybe a sheet of paper or so if you pry at them very lightly.

I did this already there was slight play with the gears but everything was all nice and smooth and the gears were spinning nicely no grinding noise or anything.

I'm sort of giving up on this gearbox and am getting a replacement.. trying out the QD gearboxes now to see how that goes. Life would be much easier with this QD spring feature.
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Draglink
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Post: #15

(07-06-2013 02:53 PM)shelcoof Wrote:  I have a few cut off lever return springs and actually have used 2. The first time I pulled it off it flew out and well is now gone lol
but I guess at this point I'm pretty desperate... I guess I'll try another

have you checked the slide contact in your trigger assembly , a broken slide contact a worn spring can cause similar issues. check your gap between the positive and negative contacts were they connect to your trigger assembly,maybe?
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