My piston is dead. What could cause this?

[Gadoury]

Hello Guys, It was only the third time i was trying out my SRC HK416 V3 PRO yesterday evening. I pressed the trigger and a really strange noise came from the gun... I removed the magazine, check if a bb was misloading... Nothing.

I'm new to this sport, don't know a lot about airsoft, but i have read a lot.

So, armed with my courage, i decide to open the gun to check wtf was happening.

Canon was nice, hop-up seem good. The gear that is attached to the motor was fine.

I had to check into the gearbox.

I have read somewhere that the SRC are a pain to dissasemble, but i was surprise how easy it was...

I found the problem, my piston is dead...



Uploaded with ImageShack.us

In the gear box, there was green plastic chips all over the place.

I just can't understand what happened.

My batteries are the recommended in the manual 9,6V 1500 MHA

I shot berely in automatic as i was only trying to zero my red dot.

played a bit with the hop-up but i saw yesterday that everything was fine on that side.

I just don't understand that last time i played with it, everything was working A1 untill now, i try to shoot and it's not working anymore.

please let me know what you think happened.

I'm about to order a World-Element Polycarbonate piston full steel teeth for v 2/3.

i'm very dissapointed to see this happened with the care i gave to the gun so far.

[m102404]

First...realize that these things are toys with a bunch of parts moving around really quickly under stress
Secondly...realize that many of these parts are made pretty cheaply
Third...realize that even the best parts can catastrophically fail
*all this despite these things cost a good chunk of money...

What's happened, in essence, is that the sector (half gear) gear has chewed up and worn away at the piston teeth. Enough so that they're worn so much that the gear won't pick them up anymore and is basically skipping past them all. Probably sounded like a horrible screeching/grinding noise right?

Most often happens suddenly when you get a jam...or if you're running a mismatched spring/motor/battery combo. Also a overall piston/head length that's too short. Yours looks more like just lousy wear leading to a failure.

Anyways...doesn't really matter why it did it...what matters more now is getting it up and running again, and hedging your bets that it won't happen again.

1. Take all the bits and pieces out of your mechbox and really clean it out....clean out the plastic shavings, the grease (that'll trap plastic shavings), etc... Give everything a really good cleaning...pick out all the teeth of each gear to make sure nothing gets left behind.

2. While you're doing that...inspect each part for damage (obviously your piston is toast). Look for broken, cracked, bent pieces...inspect the inside of the cylinder for scratches/gouges/etc...

3. Research as much as you can on the following terms
- Shimming
- Angle of Engagement (sometimes refered to as AOE)
- Compression test / testing

4. Consider what, if anything else you might want to change now
- more/less powerful spring
- spring guides
- piston head (personally I don't care for the aluminum ones)
- nozzle
- etc...

5. Get all the parts you'll need
- don't mix brands with pistons/piston heads
- don't replace just one gear...replace the whole set at once
- don't forget to get grease and shims

6. Reassemble and test
- take your time with shimming...no hurries and it really does go better to test fit the mechbox all together without the compression parts in place
- pay close attention to the AOE in your setup....if the piston you buy doesn't have the 2nd tooth already removed, give strong consideration to removing it.
- take your time and go slow...no need to hurry/rush it

Best of luck

Tys

[audi_bhoy]

I'll try to make it shorter than Ty, it's rather a jam that happened, causing the piston not to be released fast enought before the sector gear starts another cycle. Take the unjamming rod, and without anymag inserted, push the rod into the barrel, most likely some BBs will fall off the hop-up unit. You have to make sure your barrel is always clean. I clean mine before each game, and twice or three time a day with my GBB-R (Oil in propane sticks with dust, so I don't take any chances)

[Gadoury]

Tyanks guy! I'll try to follow your recomendations!

[Gadoury]

Just an update guys, The steel teeth is leaking air. I removed the piston head. The metal teeth is sliding in " plastic rail " moulded in the piston, but both of those rails broked. From outside the piston, if i push on that teeth part, it's moving !

Gosh, it must had been violent in there...

I'll get my new piston today. All metal teeth.

I'll make the compression test then. The shimming look pretty good already, there's close to no movement of the gears when the gear box is close. not even ratlle sound.

I won't replace any gear as they look perfectly fine now that i cleaned the mess. The are steel gears in this V3 gearbox.

My spring guide is also looking fine, it's an alluminum one with a big ass bearing so the spring can rotate on hitself. same for the piston head.

all my o rings looks good.

The anti-reversal latch first caused me problems as when i opened up my gearbox the first time, it came out so i didn't had the chance to see where it was going. Don't worry, i have the spring for it. after checking on google image, i saw where and how i should put it back.

So, i hope it will take care of the problem and wish it will become more reliable then.

[Gadoury]

Hey guys, important update today, my new piston just broke again !

men, i guess this gun is simply shooting to hard... i guess i should downgrade the stock spring for a 110 or something...

the gun was shooting fine! i did get at least 3000 BBs shot really well with the new piston...

here is a picture of the mess this time :



Uploaded with Bananas

So, as you can see, the piston broken where the head is... the head is fine but the bearing took quite a hit!

Do you think changing the spring will stop costing me pistons ?

Cheers !

[StrikeFreedom]

SRC Gen 3 Pro comes with a M140 spring, did you not swap it out yet? Also the cylinder head does not have a sorbo pad, that maybe something you should look into as well.

[T@NK]

The new piston is an element one, isn't it? Don't use it, their piston body are made of plastic, even their full metal teeth, they are made of cheap metal.

Few suggestions:

1, Don't use full metal/steel teeth piston, they are gonna wear out your gears really quick, get a nylon fiber/polycarbonate piston with 1 or 2 steel teeth.http://www.redwolfairsoft.com/redwol...l_Gear_Set.htm

2, no need to downgrade it to m110, try find a branded m120 spring. As a matter of fact, m120 is the perfect match with good balance of fps and durability.

good luck

Tank

[HKGhost]

If you're having lots of piston problems, it may not be the piston's fault. You need to check everything that makes contact with the piston including the gearbox shell. Check for clearance, contacts and make sure nothing is binding when everything is closed up.

[THe_Silencer]

Try adjusting the AOE: http://www.airsoftforum.com/board/lo...p/t148926.html
Get a better piston too. Stock TM pistons are quite strong and are known for gradually wearing down as opposed to catastrophically failing.

[Amos]

YouTube - Amos Airsoft how to: AOE and the ARS MASK kit!

I made a video on AOE

It covers the install with ARS stuff, but you can apply the basics to any set up.

[Kos-Mos]

The stock SRC piston is garbage... that is why it stripped.

The replacement piston you bought seems to be Element or some cheap china part, that is why it broke.

Try a Modify Ultra Speed piston (white one). I have one in my SRC G36 and M4 and 50 000 bbs later it is still strong.

But you really should replace the stock spring with at most a 120SP. Will save you some headaches and pistons.

[ThunderCactus]

did you use loctite on the threads?
what weight of ammo are you using?
Don't buy a piston with full metal teeth, you only need metal teeth at the front, the rest should be polycarbonate to absorb the impact of the gears. If your piston has full metal teeth your going to break your sector gear.

[Whiskey]

Originally Posted by Amos

YouTube - Amos Airsoft how to: AOE and the ARS MASK kit!

I made a video on AOE

It covers the install with ARS stuff, but you can apply the basics to any set up.

The music is priceless man , good info in this video folks!!!

[CJay]

alot of info in the thread here - first off I'm just gonna say that if a piston goes that quickly even a cheap one its pretty much a sure sign that something else is going on - from the sounds of it the 140 spring is to blame and I'm not surprised really. like the guys said - use a 120 and u shud be good and not have the same probs.

As for piston choice I'd go for a modify 9 times out of 10 because I've had nothing but good luck with them. just another quick side note - metal or plastic teeth - virtually no difference unless ur gonna be grinding away in full auto continually. one thing i will say is that the plastic teeth are more likely to cause less damage when and if they blow out like that. now saying that I know the risks and custom build guns all the time and like i said I'm partial to metal - always use the modify titanium tooth and rack bed super hard piston. I've been using this one in my 470 FPS dmr for 2 years now and openin it up to check it now and again it's still in amazing condition and thats with using a 35C lipo on it so moral of the story is - if u use the parts right then u'll be fine reguardless. plastic will suit ur needs absolutly fine but only if u buy a lower powered spring to accomodate it. like somebody above said - reguardless of how many metal parts u throw in or plastic parts - it's plain and simple a cheaply made toy that will break someday, somehow lol. welcome to the wonderful world of airsoft - u can check ur wallet in at the door with our staff :P