Mystery: Constand Piston Damage

[Heimdall]

Shooting with an ICS M4, stock gear set (reshimmed), an 11.1 LiPo battery, and a TM EG1000 High Torque motor. I use two uppers, one for indoor (320 fps) and another for outdoor (400 fps). Both use a polycarbonate piston set. The gun is always shot in semi.

The piston teeth always shear off... I would love some insight as to what's going on if anyone has experienced this before.

**constant piston damage. Sorry for the typo. This was posted on mobile.

[Kos-Mos]

You forgot to mention a very important factor.

What is the brand of your pistons? Stock ICS? That is normal, they are shite.

[Heimdall]

Right, one is modify and the other was bought and installed by my local gun doc. It's modify or a higher brand.

[Stealth]

Did you correct your angle of engagement?

[Kos-Mos]

Modify purples always exploded in my guns. Other swear by them...

Modify whites are good, amongst the best.

Best is TM original... theses are incredible.

[Styrak]

It's your probably your battery, much too powerful. Depends on the C rating though, what is it?

[Heimdall]

I'll have to check the C-Rating when I'm home. As for the AOE, I have to clean out my lower gear box big time so I'll do check that while I'm at it.

The modify piston is black with gold trim while the other one is a translucent white.

[lurkingknight]

sounds like sorbo is what you need to fix that aoe/pre-engagement.

Also, I will rehash a bit of info that was given to me by one much wiser about materials.

polycarbonite is not very resistant to shear forces, like say, the sector gear slamming into a piston rack or a pickup tooth on the piston. It's strong for taking a direct hit across it's surface, but it can't twist or be pulled as well as just take a straight impact. And the term 'polycarbonite' is sometimes used to describe materials that are not, indeed polycarb. What you want to use is a fiber reinforced polymide piston, they are generally not clear, you'd be looking at something like a CA blue with metal rack or a SHS with metal rack.

metal rack will also be stronger against teeth shearing,in fact they won't ever shear... but if you don't fix your pre-engagement, your gears will still start a second cycle before the piston has finished the first and the sector will plow into the rack, which usually leads to the next weakest thing to break, usually a gear or you warp a bushing/bearing.

[Heimdall]

Originally Posted by lurkingknight

sounds like sorbo is what you need to fix that aoe/pre-engagement.

Also, I will rehash a bit of info that was given to me by one much wiser about materials.

polycarbonite is not very resistant to shear forces, like say, the sector gear slamming into a piston rack or a pickup tooth on the piston. It's strong for taking a direct hit across it's surface, but it can't twist or be pulled as well as just take a straight impact. And the term 'polycarbonite' is sometimes used to describe materials that are not, indeed polycarb. What you want to use is a fiber reinforced polymide piston, they are generally not clear, you'd be looking at something like a CA blue with metal rack or a SHS with metal rack.

metal rack will also be stronger against teeth shearing,in fact they won't ever shear... but if you don't fix your pre-engagement, your gears will still start a second cycle before the piston has finished the first and the sector will plow into the rack, which usually leads to the next weakest thing to break, usually a gear or you warp a bushing/bearing.

Interesting food for thought, thanks. As for the metal teeth, both my pistons had metal teeth. Forgive me if I'm crossing terms as I'm not particularly fluent in specific airsoft tech.

I have to buy at least one new piston. Any recommendations? CA Blue? TM Stock?

[lurkingknight]

full metal rack means all teeth on the piston are metal, not just the last one.

For the money, the SHS one is probably the best bang for your buck.

[Off_kilter]

http://www.airsoftstore.ca/index.php...products_id=23

Great retailer and great piston!

[Heimdall]

Originally Posted by Off_kilter

http://www.airsoftstore.ca/index.php...products_id=23

Great retailer and great piston!

Is this unanimous? Also is there some guide for gear timing or just conjecture?

[Stealth]

Originally Posted by Heimdall

Is this unanimous? Also is there some guide for gear timing or just conjecture?

Gear timing as in.. where you should set your sector gear when you're closing the gearbox. Not really, it doesn't matter as long as it doesn't let your tappet plate snag on your gearbox shell and things are popping off all over the place.

The SHS 15T is probably the best piston FOR THE MONEY. The Lonex Red piston is twice the price of the SHS 15T and is a very good piston as it's a clone of the Supercore and Prometheus Hard pistons for half the price of those. I don't know the current price of the Modify Quantum piston but I used to own 2 and the plastic underneath the rack cracked and eventually caved in, even with AoE correction. Technically the piston was still useable.

Many users have had great success with the SHS and Lonex pistons, especially in high performance setups. I don't think you need to spend big $ on a baller piston, from what you've posted about your current setup.

[Heimdall]

Great thanks Stealth. I'll be working the fix over the next few days and post how it goes. Thanks for the tips

[Kos-Mos]

Gear timing is a myth.

Are you running a MOSFET unit to reduce your fire rate?

If not, it might be why. a 11.1v LiPo is too powerful and fast for a sub 400 fps setup. It will cause the gears to hit the piston before it is reset forward. That is a guarantee you will destroy gears (at first, the piston body will flex to allow the gears to reset, but the tooth will break off over time)

In your case, it would probably if/when you get a jam or stuck BB in the barrel/hop-up. The piston could not move forward fast enough because of the added air pressure.

I assume you can work your gun by yourself.

You can take out the mechboxes and fit the two halfs with only the rear body pin. It will be locked just like in the gun, and you can see a bit in the crack. Might give you a bit of insight (and you can see if the AoE and alignment of the gear/piston is good).

Also, Modify Super whites are the best that are easy to get:

http://www.airsoftparts.ca/store2/in...oducts_id=1369