ICS Split Gearbox Woes

[Miki01]

So the best part about ICS finally decides to rear it's ugly head around...

I picked up a metal upper and lower receiver from another member on here and swapped out all the internals. Everything went smoothly since it's just a case of swapping the both halves and putting everything together.

That's where I ran into some problems. Both halves went together smoothly but it seems as though there was a bit of a gap on the left side of the rifle.

Upon connecting the battery and having trying it out in semi I only heard the sound of the motor spinning and faintly nicking the plastic tooth an the piston.

I split the gearbox open again to confirm this. What I did next was remove the upper gearbox from the upper receiver and place it on top of the lower gearbox and ran the gun in semi as well as auto. Everything meshed fine and it was pumping out air like it's supposed to.

I re-installed it back into the upper receiver and buttoned things up once again, and still that minor gap was there and the teeth still were meshing.

Any ideas?

I've attached some images below, and yes I know the slide catch isn't installed (took it out for ease of wire movement (front wired) while I attempted to diagnose the problem). Also, apologies for camera phone photos.

Thanks.

[Desmodus]

Did you make sure that the lower gearbox was properly seated in the lower-receiver? I've noticed sometimes when reassembling that you need to push it down a bit so its properly seated inside, as sometimes it'll wiggle out. Could be causing the issue maybe?

[Miki01]

My apologies, it's been a while since I used a forum to host uploaded images.

Photos are up now.

The lower gearbox is seated perfectly. If anything, it would be perfect if it could sit higher, but there isn't much of a possibility in that case, since the receiver pins are holding it in it's only possible position.

[HKGhost]

Split the two halves of the receiver and reinstall only the upper gearbox onto the lower. Cycle the gun and confirm that it's working. If it cycles normally and everything thing seems ok, then the issue lies with the upper receiver. If you instal the upper gearbox but it still doesn't cycle, then you have gearbox issues.

[Miki01]

Originally Posted by HKGhost

Split the two halves of the receiver and reinstall only the upper gearbox onto the lower. Cycle the gun and confirm that it's working. If it cycles normally and everything thing seems ok, then the issue lies with the upper receiver. If you instal the upper gearbox but it still doesn't cycle, then you have gearbox issues.

I already did that, both last night as well as tonight.

Gun cycles with the upper gearbox only installed to the lower. When it's in the receiver, it isn't allowing the upper gearbox to sit low enough to mesh with the lower gearbox.

I was thinking of filing down some material from the upper receiver so that it would sit lower, then just add spacing to the upper part in order to keep the gearbox in constant mesh. I don't think ICS QC is that bad that it would require that, though...

[Styrak]

Is the space uniform across the entire receiver? Can you take a pic of the entire space, or at least the back part of the space near the stock tube/rear pin?

[HackD]

Any chance you got that small spring that centers the barrel on the hop-up out of place, when you removed the upper gear box? If that gets jammed in anywhere else but the slot it's supposed to be in, then the gearboxes won't line up.

I've had occasions with my M4, where the symptoms are similar after i've messed with it - it takes a bit of a subtle touch to get things lined up correctly before closing it up sometimes. Of course, it also doesn't help that the body pins are starting to wear oval in the metal of the lower receiver, either.

[JerryMcGoulBerry]

This is like my mx5. Make sure that the tappet plate it behind the sector gear. You have to pull the tappet plate behind the little nob on the sector gear.

[Kos-Mos]

Are you using the lower mechbox from a Cansoft ICS? If so and you got one of the 2006 lower receivers, it won't fit properly.

I had similar issues with mine (I managed to secure a lower and bought a clear to complete it). You can try to loosen the grip screws before closing the rifle, then tighten and test. If it solves it, it's because the lower mechbox sits too low in the receiver and the grip pulls it down.

Are you sure it's the piston getting damaged? Recent ICS gears have issues with the bevel separating and causing a screeching noise. If your shimming is not good enough, the upper can force the lower a bit and cause more friction, letting the bevel slip as described.

[Miki01]

Originally Posted by Styrak

Is the space uniform across the entire receiver? Can you take a pic of the entire space, or at least the back part of the space near the stock tube/rear pin?

Photos are attached.

The left side seems to have more gap than the right side...

Originally Posted by HackD

Any chance you got that small spring that centers the barrel on the hop-up out of place, when you removed the upper gear box? If that gets jammed in anywhere else but the slot it's supposed to be in, then the gearboxes won't line up.

I've had occasions with my M4, where the symptoms are similar after i've messed with it - it takes a bit of a subtle touch to get things lined up correctly before closing it up sometimes. Of course, it also doesn't help that the body pins are starting to wear oval in the metal of the lower receiver, either.

I centered the spring. I caught that while I was installing it for the first time.

Originally Posted by JerryMcGoulBerry

This is like my mx5. Make sure that the tappet plate it behind the sector gear. You have to pull the tappet plate behind the little nob on the sector gear.

It's behind the little nub thing.

Originally Posted by Kos-Mos

Are you using the lower mechbox from a Cansoft ICS? If so and you got one of the 2006 lower receivers, it won't fit properly.

I had similar issues with mine (I managed to secure a lower and bought a clear to complete it). You can try to loosen the grip screws before closing the rifle, then tighten and test. If it solves it, it's because the lower mechbox sits too low in the receiver and the grip pulls it down.

Are you sure it's the piston getting damaged? Recent ICS gears have issues with the bevel separating and causing a screeching noise. If your shimming is not good enough, the upper can force the lower a bit and cause more friction, letting the bevel slip as described.

Not sure what Cansoft is, but the original gun is an ICS-141 RIS Sportline. The lower receiver is a smoked clear. I'm not sure how to tell if it's a 2006 model since I got it used from a friend. It has an 'Infinite' motor in it, if that means anything.

The piston is definitely getting damages, as the first tooth has show a but of wear. It's at the extent that I'll be needing to replace it before I can keep going and diagnose this further. Shimming *shouldn't* be an issue since I haven't touched the lower or upper gears at all. It ran smoothly and somewhat quietly in the original plastic receiver.

[muddertrucker]

If you take both body pins out will it line up properly?

[Miki01]

Originally Posted by muddertrucker

If you take both body pins out will it line up properly?

Both pins out, there isn't a difference. I think it's how the gearboxes six in the receivers.

[muddertrucker]

Try switching back to the old receiver one at a time to see wich one is causing a problem.

[Cs]

This may sound stupid but are the gears in the right position for conecting the upper receiver to the lower?

Sometimes if the flat spot of the gears aren't at the top part of the lower gear box the gun won't fit together right.

[Kos-Mos]

Originally Posted by Miki01

Not sure what Cansoft is, but the original gun is an ICS-141 RIS Sportline. The lower receiver is a smoked clear. I'm not sure how to tell if it's a 2006 model since I got it used from a friend. It has an 'Infinite' motor in it, if that means anything.

The piston is definitely getting damages, as the first tooth has show a but of wear. It's at the extent that I'll be needing to replace it before I can keep going and diagnose this further. Shimming *shouldn't* be an issue since I haven't touched the lower or upper gears at all. It ran smoothly and somewhat quietly in the original plastic receiver.

You had a Cansoft (smoked receiver). The mechboxes made for theses are known to have tolerance issues and not work properly with the regular ICS stuff. I had to change mine for a normal one (I guess your lower mechbox is black?), costs about 25$ anyways, not that bad, and you can find some from time to time here.

But before that, simply unscrew the grip, install the upper receiver then screw the grip back on (only set them don't tighten) and try. If it works, you can trial-error your way out with some electrical tape inside the bottom of the lower receiver.