Need help with V2 gearbox issue (nothing's moving)

[Smokes]

Hi, hello I'm Smokey and I bought a C-TAC M4A1 last year tried to deck it out and broke a screw to keep the pistol grip stapled to the gearbox. I don't know what spring it was that came with it stock all I know is the thing shot 450 fps (as the retailers describe it). The gearbox looks identical to a VFC with the same trigger assembly and even a notch on the exterior of the gearbox for a working mock bolt catch.

Fast forward I decided to buy a new gearbox shell because either way I needed to put a spring in with less power to hopefully get it to 350 fps for indoor fields. So today was the day I finally gave myself a day to work with it. I watched a few videos on Youtube about disassembling and reassembling standard version 2 gearboxes, swapping springs and the works and felt I was confident for the task.

Disassembly went pretty well, initially opening the gearbox caught me off guard when the power spring pushed the cylinder out but I didn't notice any parts missing, maybe some shims but I didn't hear anything hit the floor or the walls.

Starting with the plate that engages the selector lever, then to the trigger assembly, to inserting the gears and the anti-rotation nub and finally working my way to the cylinder head, piston, tappet plate and squeezing the damn spring and spring guide back in.

I had trouble putting the gearbox back together cause the spring which puts tension on the trigger kept slipping away and I'd need to reopen it to get all that squared away.

I connected my MIAD grip to the gearbox, got out a 7.4 lipo that came with it and tested the thing out only to find the motor trying it's hardest to turn the gears but to no avail. Thinking it might be a weak battery I tried a 7.2 lipo I believe it is that came with a VAL I bought later on. Same problem.

I opened the gearbox back up thinking the piston wasn't engaged correctly on the tracks inside the gearbox and tried again. No avail. And again thinking the anti rotation nub wasn't correctly in place. I've even tried inserting the motor in the opposite direction to see if I just had it in backwards.

I'm stumped. This is my first airsoft gun ironically (well other than clearsoft wal-mart POS'), and my first time cracking open a gearbox and working on it intimately. I read another forum post with someone who has a similar issue with a lot of feedback saying the it was inadequate parts like not having a powerful enough motor or the piston being too heavy or something like that. But to me that doesn't make sense 'cause I'm downgrading to an guarder SP-90 non-linear when the stock spring is a bit shorter but has A LOT more resisting tension. If anyone has any tips or feedback, share away I'll try them one after another.

[Styrak]

It looks like a VFC because IT IS a VFC. "CTAC" just rebrands other stuff. They don't actually make anything, it's just a Canadian rebranding company.

Did you shim it properly? Do you know how to shim?

[Smokes]

Originally Posted by Styrak

it looks like a VFC because IT IS a VFC. "CTAC" just rebrands other stuff. They don't actually make anything, it's just a Canadian rebranding company.

Did you shim it properly? Do you know how to shim?

To be honest I really don't. I watched a video that said a good shimming job was to lay out the spur gear then gauge the bevel gear to the appropriate height with shims and do the same with the sector gear, so I tried to replicate that method as best I could.

And I kind of figured it was just a rebranded VFC but I wasn't 100% sure.

[Sequential]

Originally Posted by Styrak

Did you shim it properly? Do you know how to shim?

I don't even think the man knows how to put the gearbox back together properly.

If its a stock VFC gearbox then shimming is not required as they have those unreliable auto-shimming thingy for each gear.

[Zfurlong]

Are the wires on correctly? Do you have anything cross wired? Is there a gap in the wire coating?

[Styrak]

Originally Posted by Smokes

To be honest I really don't. I watched a video that said a good shimming job was to lay out the spur gear then gauge the bevel gear to the appropriate height with shims and do the same with the sector gear, so I tried to replicate that method as best I could.

And I kind of figured it was just a rebranded VFC but I wasn't 100% sure.

You can test the shimming with just the shell and gears in, nothing else. Then screw down the gearbox and try turning the gears through the cylinder window.

[Smokes]

Originally Posted by Zfurlong

Are the wires on correctly? Do you have anything cross wired? Is there a gap in the wire coating?

I don't think there's anything wrong with the wiring, I forgot to mention this but I connected the motor to the battery and left it outside the pistol grip, pulled the trigger and the motor was spinning.

[Red Dot]

As mentioned you can test the gears with the shell closed and spin them with your finger. I am not a tech but maybe the motor height is way off and jamming the bevel gear hence nothing is spinning, try lowering the motor height to see if that was it.

[Zfurlong]

Do you have the wires that run along the bottom of the gearbox by the motor gap out of the way so there is enough of a gap for the motor to turn the gears?

[lurkingknight]

wires not on the right posts on the motor.

red wire to the pin by the post that's colored red. black wire to the unmarked pin.

[Smokes]

Originally Posted by lurkingknight

wires not on the right posts on the motor.

red wire to the pin by the post that's colored red. black wire to the unmarked pin.

you mean red on positive and black on negative? the whole end of the motor is red :wink:

[Smokes]

Originally Posted by Red Dot

As mentioned you can test the gears with the shell closed and spin them with your finger. I am not a tech but maybe the motor height is way off and jamming the bevel gear hence nothing is spinning, try lowering the motor height to see if that was it.

It was the motor catching the bevel gear. Thank you everyone, your services were invaluable and appreciation for your help knows no bounds. Now I got a hot date with a tacticool m4, and I got's to get ready. Cheers!

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