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M4 Upgrades, need help
Hey everyone, I need your knowledge, I have no idea what I'm missing here.

The situation:
- I have a stock G&P M4 I'm trying to upgrade.
- I replaced the motor pinion since it was all grinded down.
- I got a full kit tune up from Deep fire for M4 and M100 spring.
- I got a set of modify gears, high speed.

First problem I encountered when installing everything was that the gearbox wouldn't even cycle once, the motor wasn't just powerful enough for the high speed gears which required more torque.

Fair enough, I changed back the spur and bevel gear for the stock ones and only left the cylinder gear since it had the 16 tooth for the new piston (14 teeth), whereas the G&P cylinder gear had only 14 teeth (for a 12 teeth piston).

But now, even when trying with both springs ("stock" and the one that came with the kit), the gearbox still blocks regularly. It first cycles fine, but eventually get stuck for no apparent reason, like with the high speed gear, just as if the motor wasn't powerful enough.

I have no idea what's happening here, but it's frustrating, even more as when the gearbox blocks, it's obvious that the piston is far from "2 teeth away" of being released, so I'm not even sure now that going back to the piston setup will help Huh

Any idea?
And addition question: if I end up getting a stronger motor, do I need a higher voltage battery too or will a 8.4V still do the trick?!


Edit: changed the post title to reflect new issues, see below.
M100 is not strong. There is no need for a high torque motor as even if i works, you're merely working around the problem rather than fixing it. The quick summary is that you're having too much friction.

Which Modify gears do you have? Is it the drop-in set (3 gears in a brace), or 3 individual gears??
It has nothing to do with motor strength, it sounds like your gears are locking up. Have you properly shimmed everything? An improper shim job could cause enough wobble to lock the gears up like you've mentioned. What about enough lubrication?

If you're mixing sets of gears (sounds that way), that could be your problem right there. The ratio might be just far enough off to lock up your gearbox.
Well, the shimming is good, I spent hours on it since it was what killed my first pinion (the stock shimming was utter crap), and the ratio on the cylinder gear itself looks the same as the stock's, which is why I thought I could mix it in this case (the ratio seemed only to differ on the bevel and spur gear).

I just tried back with all stock, properly shimmed and all, and it's still locking somehow... I'm actually starting to think I might have been using low batteries all along, because this doesn't make sense anymore.

Thanks for the input though, now that I know that motor strength isn't involved, I'll try again with the tune up kit once I figure out the problem since I really want to use it!
Yeah... seems like I was testing all along with an empty battery... that explains it... damn I'm such a retard sometimes, back to putting the kit all back in >_<
Oh Ycare,
King of Questions
I lol'd

I guess its better than going out and buying new gears or a burnt motor.
Guys, I'm getting nuts here, already don't have much hair left, but this is not helping. Maybe some of you will have a better understanding than me on this.

The situation:
- I have this G&P M4
- Somehow it kept on grinding the motor, regardless of motor height, and the accuracy wasn't the best. Gearbox was also quite noisy so I decided to upgrade.
- Bought a full tune up kit M100 for M4 from Deep Fire, a set of high speed Modify gears, and a Deep Fire motor pinion.

Ok, now the results, all of them properly shimmed, with full battery, well lubed, and tested with 0.20g BBs.
- As stock (and spring cut for Japanese limits): ~0.9J
- Full tune up kit + high speed gears: ~0.3J
- Full tune up kit - ported cylinder, cylinder head and nozzle (used stock instead) + high speed gears: ~0.6J
- Full tune up kit - cylinder, head, nozzle and spring (used stock and cut spring instead) + high speed gears: ~0.6J

Additionally to that, I tried every combination of bevel gear height, and motor height, and still have a quite high pitch noise every time I shoot, much noisier than any of my other AEG...

So I don't get it at all, why a full tune up kit meant to deliver ~100mps gives me a flimsy 0.3J?! Can a heavy cylinder make a difference of 0.3J, explaining why even though I almost reverted it back to stock I still get 0.6J?!
And finally, what am I missing on the motor issue, how come I can't seem to find the proper engagement at all regardless of bevel gear shimming and motor height?!


I'm lost... my next step is to try a M130 spring I have from long time ago and see if this super strong spring will be a better match for the full tune up kit...
Think step-by-step. Make sure you understand how -every- part in the GB works as a part of the whole system. Breakdown to what problems you have. from what I've read, it sound you have 2 problems :-

1) Power

I'm guessing you didn't do a compression test when you assembled the whole gearbox together. If not, do it. Make sure you have no leaks. Make sure you haven't done any silly mistakes like have the port facing the wrong way - sorry I have to throw this in after your previous battery mistake ;-). Make sure your piston head, cylinder, piston & nozzle are well lubricated.

2) Motor noise

What grip are you using? Hope it's not a MOE/MIAD.

Don't go for a M130 spring. Once again, if you do, you're merely circumventing the problem rather than trying to solve the root cause. Not to mention going for M130, you'll have to reevaluate your parts whether they're compatible (e.g. are the gears, bushing/bearings, mechbox shell, & motor suited for such power, etc.).
2 options..

Easy way, bring it to echigoya, they charge about 2k yens for the non-blowback M4s..

Hard way, start all over, the .3J might be because you missed something.. from seals to inner barrel and hop up unit connections to cylinder positioning.. and many more.. opening up your gun is fun, but you definitely need a lot of time in your first time.
This isn't his first time Big Grin. I've been to his place before with his gearbox allover the living room floor Big Grin.

Tell ya what YCare, ask Naomi to throw you and you friends a cheese and biscuit party this weekend and we'll have a GB Tuning Lesson. 101. Invite a few other friends over for a learning lesson.
can I crash the party? Tongue
Mmmh, doesn't sound like a bad idea actually Q! Let me talk about it with Naomi tonight and see what the schedule is like, but I'd definitely be very interested in that idea ^^

To answer all of the suggestions:
- Hum... what is a compression test?
- Ports facing the wrong way? Well I couldn't find any guide nor picture of a mounted ported cylinder so I had to use my crazy brain power and assume the ports where supposed to be at the opposite end of the cylinder head, else I don't see how any air can get compressed through the nozzle Undecided
- Everything is ubber lubed, but not greasy usual ACM way, just properly done... And yet somehow the seal within the Deep Fire cylinder head (the one in contact with the piston head when pushed) started breaking apart after a few shots... weird.
- I am using MIAD with new grip/motor plate as you showed me last time. Why? Known issue with it?!
- Thanks Torch, I might end up trying both solutions ^^
Haha! you guys are funny! bring it to the game next time and ill show you during lunch time. you might want to check the height of the motor as well. if you think the shimming is good but its still making the threading sound then its the height of the motor.
I'll say no more until I get my cheese and biscuits ;-). Hahaha!!

1) compression test
a) Stolen from ASF: "To do a compression test, take the cylinder and piston assembly out of the gun. Put your thumb over the end of the cylinder head and try to push the piston assembly down into the cylinder. If the piston slides in easily then you have a compression issue. If it doesn't slide in, or very little, then your compression is fine. "
b) Q's addition: "Do the same as (1a) but now with the nozzle attached too

If both (a) & (b) passes, then check your bucking/hop sleeve...make sure it's not torn.

2) cylinder port
The ported end should face away from the nozzle...naturally. So yes what you said above is correct. But I had to throw that in for you to doublecheck. You know I"m gonna keep quoting your battery mistake ;-).

3) greasing, did you use the right silicone!? I hope so...hope U didn't use something corrosive that's eating the cylinder head o-rings!

4) Grip, you're using the new metal base? Make sure your motor endbell cap sits flushly and firmly in there.

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