V2 Gearbox Rebuild, Motor Height and Locking Up Issues

[Liam Porter]

I'm fixing my step-dad's G&G for him, as it had a slight problem a while ago. The spring snapped in quite a few different places, a couple of the gears broke, the tappet plate snapped, the piston teeth were all shredded. Not too sure how it happened really, but the gun was bought second hand, the previous owner had cut the spring, and after a year of my step-dad owning it, it broke a little.

So, he put some spare parts from an exploded APS gearbox in it, so it had bit of a mismatch of random brands.

One of the gears was G&G, the other two APS, the piston was APS, an SHS tappet plate was bought and put in it, along with an SHS M90 spring. The stock G&G motor was replaced with a spare G&P M120 which I had lying around.

On testing that set up, the piston stripped instantly. My step-dad's solution was to buy a stronger piston, so he bought an SHS full metal toothed piston, put that in, and the result was a really low rate of fire, with the motor struggling a lot to do anything.

He thought it might be the gears, so he bought some SHS 16:1 gears, and my job yesterday was to fit them and hopefully get the gun working again.

I gave the gearbox a clean, fitted the new gears, put everything else back in, left the motor height as it was, as it seemed to be engaging properly, the first thing that happened when I fired it was it jammed and broke a tooth off the bevel gear.

He has another gear set the same, so I have that to put in it. But, thought I'd try and fix the jamming/locking issue with the current, slightly broken gears rather than risk ruining some more new ones.

Found out that the motor couldn't actually screw in anywhere near far enough with the spring on it. I'm not sure why, not sure if it's because it's a big pistol grip, but the plastic bit that screws onto the gearbox seems too thick. If I take the spring off the motor, then it can go in far enough, so, I cut a section of that spring two coils in length and used that, just to make sure the motor wasn't going to move around too much in use.

Put it all together, with the broken gear, it fires, great. Makes some horrible noises though, the motor sounds as if it's straining quite a bit still, and the gears sound to be grinding. Take it apart again, check the shimming, loosen it a little, add a little more grease, put it together, it works!

Now onto the current problem I have.

I took it all apart again, as it's not much good having the broken gear inside it. Put the new gear in, and now it just won't work.

Connect the motor etc. and try to fire, it does almost a complete cycle, but locks with the piston as far back as it can get, every time. Tried it on full and semi auto, no difference, the only way to unlock it is to take the gearbox apart.

So, I'm stumped. Does anyone have any ideas what is up with this?

Here's a list of the internals it has:

- G&G gearbox shell

- SHS metal toothed piston, came with a piston head

- SHS 16:1 gearset

- SHS tappet plate, with stock G&G nozzle

- Stock G&G trigger assembly

- Stock G&G cylinder and cylinder head

- Stock G&G anti reversal latch

- Not sure on the spring guide, either APS or G&G, it has bearings on it though.

 

[Airsoft-Ed]

"V2 gearbox rebuild"

There's your problem.

 

[Liam Porter]

Yes, but unfortunately, I can't change that.

 

[CaptainSwoop]

wrong forum?

 

[Liam Porter]

wrong forum?

Maybe so, but the last time I used the Advice and Technical Help section, my post sat there for a week and got no replies, until I mentioned it in a post in this section and it got moved to this section. I'm only at home for a few days until I return to uni, and want to get this sorted by then, so I don't have time to wait a week for replies.

 

[RR01]

Have you checked that the battery you are using is fully charged, as a below par battery can give that sort of problem? The other problem with the motor height may be that you have cut the spring too much, so that it goes in too far. The other possibility is that you have lost the small metal disc that sits between the motor and the height adjuster screw (presuming you have the adjuster plate with the very small grub screw, not the large slotted screw). If so, the adjuster screw will press on the end of the motor shaft and stop it turning properly without the small metal disc in between the two.

 

[Liam Porter]

Have you checked that the battery you are using is fully charged, as a below par battery can give that sort of problem? The other problem with the motor height may be that you have cut the spring too much, so that it goes in too far. The other possibility is that you have lost the small metal disc that sits between the motor and the height adjuster screw (presuming you have the adjuster plate with the very small grub screw, not the large slotted screw). If so, the adjuster screw will press on the end of the motor shaft and stop it turning properly without the small metal disc in between the two.

I've tried different batteries, tried a total of 6 9.6v, 1600mAh batteries, two wired at a time, giving 9.6v, 3200mAh. All of the batteries are charged, and all work in my brother's G&P M4 and JG G36.

The motor isn't going in too far, with it in literally as far as it can go, it sits at the perfect height. It has the large slotted screw, and the bottom side of it is slightly hollowed out in the middle to make sure that it isn't touching the moving parts of the motor.

 

[RR01]

Just one weird suggestion, but is the sector gear the right number of teeth for the piston, i.e. if it has a 15 or 16 tooth piston does it have a 15 or 16 tooth sector gear to drive it? Other than that, there doesn't seem to be anything else you have described that should stop it cycling properly, but fitting a mismatched gear set could be the problem. The other thing to try is to refit the gearbox without the piston and spring and check that it spins up properly by the motor with no tension on the gears. That would at least eliminate the gears themselves from the problem and leave an AOE, or piston / spring / spring-guide error as the cause.

 

[Liam Porter]

Should they have the same? The piston has 14 teeth and the sector gear has 16, but after catching the piston, there's a gap for two teeth, and then the final tooth catches the end of the final tooth on the piston.

It has a matched gear set in it now, the old mismatched one caused it to do funny things.

I've done everything I can think of, I put one thing in the gearbox at a time and attached the grip and motor, to eliminate each gear being a problem and to put shims in the right place. I tried it with everything in, apart from the tappet plate and it worked, and tried it with everything apart from piston, cylinder, spring and spring guide and it worked, but will it all in place, it just stops after almost completing the first cycle.

Just tried it with the biggest battery I have, and it fires, but makes a horrible screeching, no matter where the motor is adjusted to, and the wires get extremely hot, just started smoking...

 

[Unrustle_Thine_Jimmies]

This is a long shot,but could it maybe be a shimming issue? Try shimming the gun Bevel to Pinion. This is the source of 90% of stress and screech i find and hardly any people I meet shim this way,shimming each gear individually or starting with the spur creates a lot of stress. I nearly wrecked my shs gearset when I shimmed that way,the screech and grinding was atrocious. Shimming bevel to pinion helped a great deal.

I'm still a bit of a noob to anything except a VSR. My AEG knowledge only expands as far as correcting AOE,shimming and wiring a mosfet

Here's another, longer shot.

I've seen some V2 gearboxes,JG actually, which have some reinforcement around where the gears are(For some stupid reason...probably to make up for poor casting) Requiring it to be filed to fit other gearset(probably a reason I see a lot of JGs really tightly shimmed)

Maybe G&G stuck in this extra material on newer models?

 

[Liam Porter]

It's an old, old model, my step-dad got it 3 years ago, second hand, guy before had it a year or so I think.

Either way, it's sorted, he had a go and put it together, and broke another SHS bevel gear. I had another spare, not sure on brand, but same size, same number of teeth and same spacing/size teeth. Shimmed it using the video you just posted, only difference between the end result of that and what I already had was 1 shim less on the sector gear. Doesn't make too much noise, motor height is sorted, after cutting down the spring that goes over the shaft. Put it all together and it works, no horrible screeching, no excessive heating of the wires, nothing noticeably wrong.

Currently it's not feeding, I don't think the tappet plate is going back far enough, which isn't any good, but I think I can solve that with a delayer chip on the sector gear, or maybe removing a tiny bit off the nozzle? Got spares if the tappet plate/nozzle get messed up though.

Managed to get one shot through it - 384 FPS. The spring isn't an M90.

I think it's an M100, only two packagings I have are SHS M90 and SHS M100, I used the M90 the other day in my friend's M4, and this spring I have in the G&G looks exactly the same, so I presume it's the M100.

Couple of new questions, can I gradually shave a small amount off the end of the nozzle allowing BBs to feed into the hop chamber? Or will this cause more problems than it's worth?

And, what spring to drop to 320-330 FPS, considering M100 is giving 380+?

 

[Unrustle_Thine_Jimmies]

I think shaving the nozzle will be far more trouble than what it's worth

 

[Liam Porter]

Any ideas on the problems? Not sure I really want to open the gearbox again.

 

[Unrustle_Thine_Jimmies]

Could be that the spring for the tappet plate is not installed correctly,or that the sector gear chip thing isn't pulling the tappet back far enough.

 

[Liam Porter]

Spring for it is definitely installed correctly, I think the sector gear clip is the problem. I have no idea on the the brand of the tappet plate, could be stock G&G, making it nearly 4 years old, or it could be TM or APS, and it's using SHS gears.

I also have a spare tappet plate, so I'll try that out tomorrow, when I can be bothered to take the gun apart again.

If that doesn't work, then I'll try either getting a delayer chip for the sector gear (my friend's G&G M16 needed one), or an SHS tappet plate, so it matches the gears and gets pulled back hopefully the right distance.

Thanks for all the help, spend literally all day trying to fix this gun, must have opened and closed the gearbox over 20 times!

 

[RR01]

After a lot of use the part of the tappet plate that connects with the pin on the sector gear can get worn down, so that it doesn't pull the nozzle back enough to allow smooth feeding of the bbs. A delayer chip will help that, but can also introduce its own problems, as it can result in double feeding bbs because the delay is too long (had that on one of my M4s). If the spare tappet plate you have is less worn then that may solve the problem.

 

[Liam Porter]

Yeah, I'll try the spare before I buy anything new, if it does need a new one then I'll probably get a new tappet plate.