Need Help With Gearbox

[Leok40]

As the title states, I require some assistance with my GB.

Roughly 7-8 years ago, I purchased an Aftermath Kraken. This is no longer the one you see on their website. This one is old. Came with a clear plastic body and olive green stock, grip and hand guards.

Anyway, after some cosmetic upgrades like metal receivers and wood replacements for the olive green pieces, and some performance such as a tight bore barrel I need help on diagnosing my gearbox.

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My first question is about the sound of the gearbox. I have taken it apart a couple times to re grease, and everything seems okay except maybe the shim job and the fact that the piston o ring has noticeable wear.

The sound it makes is that of a "loud hit/clap." I've seen videos of how gb's sound and mine sounds nothing like it. Mine has more of an explosive bang, kind of how gbb pistols sound.

I believe that this possibly may be the sound of lots of air leakage, as my o ring is worn. If I drop it into the cylinder and hold the end closed, it falls right in. Definitely needs a replacement.

If not the worn o ring, what could it be?

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Next question is about the actual identification and quality of the gearbox. My gearbox has an inscription on one of its sides saying "CM. 02." Now I understand that it is of CYMA make, but which one?

I can't for the life of me find any details on a CM. 02 gb other than some other variants CM. 02b and CM. 02c. As far as I remember, it is advertised to shoot 370 fps with 0.2g.

Does anyone have any details or info on it? I have also attached some pictures.





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Last question. I am in desperate need of upgrades to bring it back to proper working order. I would like to increase the fps to somewhere slightly over 400. However, last time when I shot it, sometimes it would not fire for three shots, and on the fourth pull, 3 pellets would fly out at like 5 fps.

So, to get the gb back in working order I would probably need:
- O Ring replacement
- New Tappet Plate
- New Nozzle


Would I benefit by getting a better cylinder and piston + piston head? If so, could any of you recommend any brands for these internals and the ones listed above?

Now for the 400+ fps increase I would require (at a minimum)
- M120/M130 spring
- Reinforced spring guide

Thanks for the help.

[ThunderCactus]

$200 for a gun that served 8 years. I think you've earned a new gun lol
do a compression test. Most likely the o ring shrank or wore out.
Dont honestly know if any tech would waste the time to upgrade a kraken, especially given the early krakens slightly off spec mechbox. But if you're dedicated to it, just solve the compression issues first (before buying a spring), then get a high quality barrel and a flat hop and use .28g bbs. Should cover all the bases.

[Hectic]

Good gun to learn on, tear it open and have a look, nothing broken? Buy a piston and some shims and perhaps a cylinder head and rebuild it. The CM.02 Is likely a cyma gearbox.
another option would be to pay for a lonex (or a cheapo cyma) drop in gearbox and just stick that in.
I have the same clear n green kraken, I'm about to buy some body parts as the gearbox is still good in it lol.

[Leok40]

Thanks for the replies. Still wondering what causes the loud noise. I already have a Madbull 6.03 (V2 version) tb.

Nothing is broken other than the flimsy trigger guard which barely stays on.

Most likely going to get a new piston and maybe cylinder along with tappet plate, nozzle and a good hop up. Gonna try to re shim as well.

I know as far as aesthetics go, they don't matter on a gb, but with the pictures I linked it's so ugly. Has that brown loctite all over it and ugly finish.

I was considering getting a new gb, but was kind of skeptical about the jg ones or dboys. A cyma one might be good. I looked at the lonexs' before, and they are quite expensive.

Thunder, you mentioned it has an offspec gb; could you elaborate please? And maybe hectic can give me more info aswell.

[ThunderCactus]

The loud noise is from the piston hitting the cylinder head too fast since its not compressing enough air to slow it down.
i recall the first gen of krakens having a mechbox that was 1mm longer at the front, making it incompatible with aftermarket shells.

Depending whats gone through that madbull barrel it might be fucked anyway. Theres a reason any respectable gun tech wont use madbull barrels; aluminum is soft and if it gets a scratch, the barrel is scrapped. Ive never seen a madbull barrel that didnt have a scratch in it either.

[Leok40]

Hmmm, kind of torn on this at the moment. Do I buy new piston/cylinder assembly with nozzle and tappet plate, or go for a relatively cheap gb?

The Cyma 02c gb's go for around $80, but the description says they fire at 350fps or so. Would end up having to replace the spring on that and maybe piston as well.

[ThunderCactus]

If you want my honest opinion, buy an LCT.
after 8 years i think that gun has paid for itself and then some.

The major issue with chinasoft stuff like krakens, especially back in the day, was that no gunsmith would work on them because there was no guarantee of being tm spec. And thats still true for a few brands.
Most of them just honestly arent worth the time for a gun tech to fix...

[Leok40]

As far as externals go, the gun was TM compatible. Now due to the lack of info on the gb, I am not so sure.

Looking through different forums, some say the gb is TM compatible while some others say it was not.

Maybe the earliest Olive Green models were not, but according to the time stamps of other posts, it would suggest that the post 2010 ones seem to be TM spec.

Edit: I took a picture of my shell, and measured an internal dimension as well as the internal of the rear to the external of the front. I can't seem to find any specs/dimensions of gb sizes so maybe you can help me out here.

[thetuch]

Like a lot of people who have posted before me, you've run this gun for a good 8 years, which is amazing.

However, repairing this gearbox will be much cheaper than buying a new AEG. If you're looking at repairing it, I would suggest replacing the compression components as opposed to purchasing a new gearbox.

What brand are the current piston/cylinder head/air nozzle you have in the gun? That might assist us in telling whether or not its TM compatible.

[Leok40]

Alright, I decided to get a Cyma gearbox as a replacement. The new 02C model.

As far as the old gb's compatibility, the huge Kraken thread says in multiple places that it is compatible except for the barrel and hop up. However, other threads sometimes mention it being off spec, just like Thunder has.

In the new Cyma gearbox, I plan to do some minor upgrades. I'm thinking of a metal bb spring guide, as well as a better nozzle. Not sure whether I should go with plastic or metal on that.

[ThunderCactus]

Plastic air nozzle