Piston grinding

[Flatlander]

Originally Posted by byblos

i am using .28 bb's, should i change?

It's usually the brand of BB's as some have better polishes and different dimensions and tolerencing. Change if you find you're jamming often. I would consider often to be if you had one jam every game or every other game.

[LUTNIT]

I find you get the best performance with your gun if you use .25's to around 375fps and only use .28's if above that.

Also, is that a Modify piston? They are junk, I have stripped 3 in under 350fps guns with no highspeed parts. Its like the teeth don't mesh with the gears entirely so its only rubbing against the tips of the piston teeth. I use Guarder grey polycarb, Deep Fire ver.2 full metal toothed, or Prometheus hard type in my guns. I have never stripped one of the listed pistons even with 400fps 25 round/second setups.

On that note, Modify highspeed gears are also junk. I installed them in one gun for fun and the ROF went down (325fps spring.) Also the nub on the sector gear is too big to fit a sector gear clip on and its impossible without taking the bracket off.

low or medium highspeed setups work well with lower fps but true high ROF setups (minimum 30rps) usually need stronger springs, otherwise the piston doesn't return fast enough (thats when the ass end gets eaten off like Stalker said on the previous page.)

I have been experimenting with and using high speed setups in my guns for more than a year now and have made some that are very reliable. The 399fps ICS L85A2 that I installed HurricanE highspeed gears, SystemA turbo motor, Guarder polycarb piston, and 10.8V 4000mAh battery in has fired around 2000rnds (really low for a gun firing 31 rounds/second) and when you wipe the grease off the piston it still looks new. My ICS M4A1 is 390fps and 26 rounds/second and after 10-15k rnds the Guarder piston is STARTING to show a LITTLE wear on the teeth.

I have never had a Modify piston in any gun at any fps and any ROF last more than 1000-1500rnds. Might be bad luck but I refuse to use em now.

[Corpo]

Originally Posted by LUTNIT

low or medium highspeed setups work well with lower fps but true high ROF setups (minimum 30rps) usually need stronger springs, otherwise the piston doesn't return fast enough (thats when the ass end gets eaten off like Stalker said on the previous page.)

+1

my god i thought i was going mad while they were saying you wanted a weaker spring in high speed setups.

physics tell me you need to return your piston to the fully fired state before the gears grab it again or you will strip it.

i just had a interesting gun failure involving a 2 year old systema piston, the part that the spur gear hits first broke off, lol.

[Corpo]

pics, taken from my shitty cell phone

[LUTNIT]

I had that exact thing happen with a STAR L85A2 AFV I had. It wasn't a stock piston and I have no idea what brand it was but thats what happened, almost new piston too.

I did a highspeed gun once and it had a really weird grinding sound, very different from any gear grinding I heard before or since. Turns out the sector gear was eating the MIDDLE teeth of the piston because the return stroke of the piston was too slow. Was the weirdest thing to see what I removed it from the mechbox. Another strange one was a piston eaten from the piston head end backwards. Turns out I misinstalled the piston head so there was an extra sector gear tooth after all the piston teeth had been engaged. Result was the last gear tooth was beating up the metal piston tooth until it broke, then the last 2 gear teeth where beating up the second last piston tooth, etc. Got a third of the way through the piston within 10-15 shots.

Back on topic....my main advice is:

Modify, in my experience, make horrible: gears and pistons

Modify is great for: everything else (I especially love their cylinders and cylinder heads)

[CDN_Stalker]

Modify is what I swear by and have never had nor seen any issues with any of their parts, they are actually of higher quality than MOST parts I've dealt with, including Systema, Guarder, etc. I think you've just had bad luck Lutnit, but juding by the experimenting you do (insane rates of fire and such) I can see pistons not lasting you long. And the DF Titanium piston is crap, the plastic is the same as the other ones, and the one I've put in Apoc's SAW is showing cracks along the rails that hold the teeth in place.......... it's only been cycled a thousand times or so while I was setting up and troubleshooting the Trigger Master into it.

And use 0.28g all the time you want if you like, I use them constantly outdoors in all my guns (except rifles) and there is no reason to NOT use them under 375fps, I use them even down to 300fps and they work amazing then too.

[Crunchmeister]

Originally Posted by Corpo

pics, taken from my shitty cell phone

I had this happen with my brand new Systema piston (identical one) in about 250 rounds... Systema internals have been nothing but a boatload of FAIL for me. Everything Systema internal (except the silent piston / cylinder head set) I've installed has broken in less than 1000 rounds.

[LUTNIT]

But are you using a Deep Fire ver.2 piston? The first gen did have the cracking problem but the ver.2 is reinforced on the edges and I have had zero issues. I did have one of the ver.1 ones crack like you described.

The Modify pistons I have had die on me are not in experimental guns. One was in my ICS M4A1 when it was shooting 375fps and maybe 17 rounds/second, the second one was in I don't remember exactly which gun but it was a 325fps indoor gun with standard gears, motor, etc. that couldn't have been shooting more than 12 rounds/second. It just seems like I look at a Modify piston and it dies. I installed one in the second ICS M4A1 I had and it stripped without firing a shot. I pulled the trigger and there was a little pop sound and then gears free-spinning.

I dislike their gears because of those damn modular gear sets. They are so damn picky as to which guns they fit in. I tried using it in an ICS, JG, and TM mechbox and it wouldn't sit right in any of them (and I bought the one listed as for JG guns.) Their loose gear sets are okay but again, they don't use a standard diameter pin on the sector gear to draw back the tappet plate so you can't put on any standard sector gear clips to make feeding more reliable. Even at an average ROF I find that midcaps on the last 10ish rounds will misfeed, not so with a sector gear clip so I put them in all my guns now, not just high ROF setups. One interesting thing I had happen with a set of Modify gears was it rusted. Not after getting wet, not after sitting in a damp area for a week but inside a gun within 3 days. I have no idea what happened but I installed them brand new with a Modify piston using white lithium grease from Canadian Tire, piston stripped and a couple days later when I got around to fixing it the gears where brown with rust. Since they coated in rust it hasn't gotten any worse but I think its damn odd.

As for Modify being better than most I have to agree with some. The only SystemA parts I haven't had problems with are their gears, Prometheus cylinder heads aren't so great in my experience, but Guarder is great. I would use Guarder in everything if it wasn't for Modify being just as good (in everything but pistons), easier to get, and cheaper.

For pistons, hands down, no one can touch a Prometheus hard type. Seven steel teeth and reinforcements on both sides of the plastic teeth. Things are tanks, been running one in my sniper M14 for a season and last I checked it looked new still, at least a couple thousand rounds through it in the past year at 440fps with 12V battery for better trigger response in semi.

I have tested using .25's and .28's in all my guns and I find that .25's give a much better overall performance in guns under 375fps. You loose a little brush penetration but the amount of range you loose and how much harder it is to hit a moving target are really obvious. It seems the higher the fps, the less range you loose even as a percentage of the total range. So in say 390fps guns .28's don't have that much of a noticeable disadvantage in the areas of range and hitting a moving target compared to .25's. That is just what I have observed but I have only tested in my ICS CQBR and ICS are known for weird hopup reactions.

*EDIT*
I opened my AKS-74U a little while ago to downgrade it for someone who bought it. I had installed a Modify standard piston, stock STAR gears, TM EG700 motor, and 9.6V 2200mAh battery. Before downgrading it when it had exactly the same internals but a 390fps spring it had fired maybe 500rnds for testing, even after that few number of rounds the piston teeth have little dents in them, as said above a Prometheus hard type in my 440fps M14 after 2000-3000rnds still looks new once you remove the grease.

[Crunchmeister]

Originally Posted by LUTNIT

I dislike their gears because of those damn modular gear sets. They are so damn picky as to which guns they fit in. I tried using it in an ICS, JG, and TM mechbox and it wouldn't sit right in any of them (and I bought the one listed as for JG guns.)

In case you didn't know, they now make a "universal" modular gear set that can fit in any mechbox, including reinforced mechboxes.

[CDN_Stalker]

Wasn't aware of different versions of DF pistons, but I stay away from anything made by them now, not worth the risk.

I've been using the Modify piston in both my MP5s and they are still going strong, so I guess it's your evil stare that is doing it (or you are Chef to them, touch and they die).

0.28g works fantastic in all my guns (including my GBBs), so the fps is a rather a moot point. And I've used 0.30g BBs in my M24 set at 340fps and was shocked at the performance of it.

[LUTNIT]

Comparing me...to....Chef...?

*runs away crying*

[CDN_Stalker]

Originally Posted by LUTNIT

Comparing me...to....Chef...?

*runs away crying*

At least the Modify parts I install in his guns never fail. Everything else does!

[byblos]

alright so i ordered the http://www.airsoftparts.ca/store2/in...1693069fce3d79, inserted the spring guide into the compressed side of the spring, im going to grease up the piston head and rails more, only use 4 bushing rather than 6 (as the instructions mentioned for the TM cloned mechboxes).... hopefully this will help.

and since i have a M100 or M110 (i forget) spring, i should be getting high ROF and FPS with this setup?

[CDN_Stalker]

You need get a higher mAh battery, that is a critical thing for ROF unless you have a light spring. If you are starving the motor while it's trying to do hard work, no amount of upgrades will get you a really high rate of fire.

[damage]

Question is why does piston grinds?. No seriously.