piston help

[surkon]

Hi, Ive reccently purchased a G&G m4 cqb-s and to say the least I havent been to happy with it. I need help finding out why my gearbox keeps letting me down. I have attached some pictures of my upgraded piston. You can see it has been cracked along the piston slides and the piston teeth have been bent outward. Which is funny because the teeth are advertised to be "titanium". This piston was used for one 300 rd clip before it jamed the gearbox up. Anyhow can anyone put their finger on the cause of this all or have similar experience? G&G and otherwise. Thanks.

[Crunchmeister]

The wear on the teeth is all on one side of the teeth instead of the centre where the gears should contact. And it's the same side of the piston that is cracked. My first guess was it wasn't correctly installed into the rails in the mechbox. Not having seen how it was sitting in the shell after failure, I can't say for sure, but that's what it looks like. And if titanium teeth suffered this much damage, chances are the teeth on your sector gear have been damaged too.

[Skruface]

This is a known common failure of the Deepfire piston. There's a thread on airsoftmechanics.com about this exact type of failure (splitting down the side of the piston) that is inherent on all Deepfire pistons.

Try getting a competent gunsmith to install a quality piston - Prometheus, Modify, or even a stock TM piston, which is always my favorite - and shim the gears properly.

[yuhaoyang]

You can get away with any piston that has 1 metal tooth, or find one that has 3. Make sure you align it onto the rails inside the mechbox, and buy modify or prometheus or something. I'm not sure about systema aftermarket ones, the systema pistons that come in their drop-in mechboxes tend to shatter. Also, crunch is right in saying that your sector gear is probably quite damaged. Don't use full metal teeth pistons, they damage the gears, and gears cost a lot more.

[surkon]

Wow thats alot of great info. This is among my first attempts at "gunsmithing" but how do you learn if you dont make mistakes. I have no doubt that I didnt shim properly. But knowing about deepfires poor quality is great to know about.

One more thing, do you guys see any foreseeable problems with getting a complete systema gearbox to replace the G&G box? I have heard that G&G lower recievers are somewhat specific to G&G gear boxes. But I have no idea how true that is.

Again thanks guys this helps alot.

[yuhaoyang]

As far as I know the G&G reciever isn't proprietary. Wait for someone elses response, and also, it would be a good idea to replace the piston in the Systema mechbox with a modify one, or a prometheus one.
http://www.airsoftparts.ca/store2/in...oducts_id=1368
http://www.airsoftparts.ca/store2/in...oducts_id=1057

[Crunchmeister]

As far as I know, G&G mechboxes are standard V2 and any other should fit. However, It's sort of overkill throwing a $250 mechbox into that gun. I'd suggest if you don't know what you're going, get a set of Modify smooth modular gears, a new Modify piston, and you should be up and running agian in no time.

And even if you get a Systema mechbox, their pistons blow donkey cock and need to be replaced.

[DefCon 1]

Originally Posted by Skruface

This is a known common failure of the Deepfire piston. There's a thread on airsoftmechanics.com about this exact type of failure (splitting down the side of the piston) that is inherent on all Deepfire pistons.

Try getting a competent gunsmith to install a quality piston - Prometheus, Modify, or even a stock TM piston, which is always my favorite - and shim the gears properly.

+1

[dpvu]

Stay away from Deepfire pistons, I had one fail after only about 30 rounds. I've personally found the Modify polycarbonate pistons to be extremely durable.

[SHÖCK]

Deepfire pistons with a full rack of metal teeth are bad news.

The rack explodes out of the piston and they crack in half.

Better to have single-piece pistons or at least one half plastic so at least some of the teeth are molded in and not separate from the body.

[Shirley]

Note: When buying a piston, it's better to buy a half metal teeth and under than full metal teeth. It's better to strip your piston then your gears. Pistons are easier to replace.