M4 gearbox upgrade

[sparkie740]

hey guys, got an M4 with what i believe is a standard gearbox (V2) of unknown make, it works ok, shoots around 13 rounds per second on full auto at around 290 fps but seems really noisy.

i know AEG's are never gonna be the quietist of weapons but this thing seems to make a hell of a racket and sounds quite rough!

im running it on 8.4 volt mini's at the moment (1300mah) though ive just put a full stock on it to take an 8.4v 3700 mah large battery and it has a classic army high torque motor

anyways what i want to do is upgrade the gearbox, i'd ike to go around 320-340 fps with a higher rate of fire, but more than anything i want to make it smoother, quieterand ultimately more reliable.

is there anyway that i can achieve all 4 objectives? and if so what parts would i need? im on a limited budget so i dont want anything that will break the bank and if possible it would be nice to do a few parts at a time also i dont want to have to get different batteries (i have an mp5 that uses the same batteries)

any advice you can give me would be greatly appreciated

cheers

[LazyMcCrazy]

Re: M4 gearbox upgrade

m100 spring
SHS piston
Aluminium piston head (choose one)
SHS 13:1 gears

Make sure your nicely shimmed and what not though for "smoothness" and get the angle of engagement correct as my last piston lasted 900 rounds as it was wayyy off (damn you madbull)

About a £50 upgrade all in

Lube the tube and grease the gears, put it back together and your away, if you want it to run even smoother i recommended a JG red motor. I had CA High Torque and found it really noisy and felt unstable about it. Runs smooth as owt now.

Probs get about 340ish fps and 20 rounds a second on that.

NOTE: if you do change batteries on this setup to lipo, recommended you use sorbo pads. This weekend i saw a bloke shatter 2 reinforced gear boxes doing this without pads.

[richardy]

Re: M4 gearbox upgrade

if he shattered two gearboxs hes doing something else wrong. For instance the ali piston head is extra strain on the GB which isnt needed it also adds wight to your piston slowing down its return time and adding weight to the gears on pick up.

POM piston head all the time ... there shouldnt ever be an occasion when you would need an ali piston head. Not unless your making somekind of dmr setup.

Excesss noise is almost always the shiming. Reshim and polish the gb shell. Fit bearings if you havent already.

New spring, different springs have different widths and lengths yet produce the same power you may have better luck with a different brand.

New cylinder head, possibly the most under appriciated upgrade for a version 2 gearbox. different ones give different amounts of padding and protection. You shouldnt need sorbo pads with a decent "new" cylinder head, the padding on a cylinder head does harden after a period of time. All sorbo pads do is cuase problems for people who dont really know enough in the first place. A new cylinder head is a safer and easier recommendation.

[Ammo]

Re: M4 gearbox upgrade

@LazyMcCrazy

What are sorbo pads? :-/ Not ever heard of them before.

[sparkie740]

Re: M4 gearbox upgrade

the gearbox already has bearings but i wouldnt wanna guess as to the quality of them! what are the best bearings you can get or does it not make a difference?

also ive heard bad things about Ali piston heads so i think i'd rather avoid one if possible

are there any specific makes that i should be looking at (as i understand Gaurder are supposed to be pretty good?) and am i best to stick to one brand or can i mix and match? how do i know that the components i choose are gonna be compatable?

also what about the motor? i know JG are a chinese manufacturer so im guessing their stuffs never gonna be as good as say tokyo marui but can i just get any high speed motor or do i need to match it to the spring/gearset?

cheers

[richardy]

Re: M4 gearbox upgrade

motors any really .. guarder high torques popular, as is element high torque and kanzen strong type.

Internal parts you can mix and match just check that the parts are working, i prefer to keep it to one brand though. Some cylinder heads are designed for there own brand piston heads, hence why some see early failures of some piston heads. but its not common.

For the most part what ever aftermarket brand you choose should be fine. Honestly the best thing you can do is just pick and go for it.

You have a full stock, depending on how empty it is the space can amplifiy the sound of the gearbox and its also next to your ear.. a large 9.6v or large 7.4v lipo would be a worthy upgrade and fill some space.

[LazyMcCrazy]

Re: M4 gearbox upgrade

The bloke i was on about didnt break his GB using the set up i said, but it was a high speed set up with this power on 11.1 lipo, Iv been running this for months now and iv never had to alter anything since.

I also don't think a new cylinder head is necessary, Sorbo pads are so easy to use and they correct your AOE. Hes on a budget and for the amount they do its cheaper.

[richardy]

Re: M4 gearbox upgrade

Make sure your nicely shimmed and what not though for "smoothness" and get the angle of engagement correct as my last piston lasted 900 rounds as it was wayyy off (damn you madbull)

sounds good...

Pistons are all different lengths, dont assume that just becuase aoe corrected on one it has on another. There is such a thing as going to far when using sorbo pads.

Replacing the cylinder head depending on the brand doesnt have to be expensive, original pastic ones can also have the centers come loose, it IS a worth while upgrade.

A high speed setup wont break a version 2 gearbox...

[LazyMcCrazy]

Re: M4 gearbox upgrade

A high speed setup wont break a version 2 gearbox...

I saw it happen twice in one day at cqb, so would of been about 330 fps, not that powerful. He was using a plastic piston head (unlike me) and piston, this is why i would recommended them on high speed setups. Google search "are sorbo pads worth it" so far iv not come across a no. Also you get them in different thicknesses from 2 to 5mm. At the end of the day hes low on money and cant spare a new GB, decent investment i would say. But everyone has there own opinion.

[richardy]

Re: M4 gearbox upgrade

How many guns where there running version 2 gearboxs and high speed, about a million.. Now take all the other trillion users on here that are running high speed setups and havent broken there gearbox casings. Yet ill get an m4 in for repair running an 8.4v with a broken v2 casing... It has nothing to do with high speed but the amount of impact that is allowed to translate to the front of the casing verse the strength of the casing in the first place, 90% of the time the cylinder heads rubber is hard as a rock on a bog standard plastic cylinder head.

One guy breaks two in a row and suddenly high speed setups break version 2 gearboxs.. Isnt it more likely that this one guy was doing something wrong cuasing his casings to break in a short amount of time consecutively..

i dont search google i have the actual benefit of having done everything my self many times over..

[guard-sniper87]

Re: M4 gearbox upgrade

ask richardy has said

no ali piston head,

you can do quite abit of fixing with minimul ammount mate,

completly strip the gearbox and glean it free of the crap grease usually on stock guns, re lube the oring on piston head, and lightly lube the inside of the cylinder, do the shimming and piston work, try again,
if still not as fast, replace a few parts

but please use a better battery to check first, so use a 8.4 3300 or a 9.6 3500 to get a increase there and then of the rof AFTER you have serviced the gearbox

then if not happy, you can do some shopping,

all the upgrades can be done for less then 80 to get it as nice as it can be including a AB mosfet

[LazyMcCrazy]

Re: M4 gearbox upgrade

Jeeeez, just going off what i have thats never let me down.

I also dont know if it happened in a short amount of time as i dont know how long he had owned the guns.
I spoke to my sites gun tech and he said many repairs of broken GB's he has had have broke over high speed set ups and no protection? I recommended the ali piston with the pads - lasts longer than plastic ones. I like the set up as i said as it is reliable as i don't want to be opening it up every week. Iv done the mods and months down the line and many of games later its still running mint.

Just because you have never experienced this doesn't mean others haven't

Back to the OP eh?

[guard-sniper87]

Re: M4 gearbox upgrade

Jeeeez, just going off what i have thats never let me down.

I also dont know if it happened in a short amount of time as i dont know how long he had owned the guns.
I spoke to my sites gun tech and he said many repairs of broken GB's he has had have broke over high speed set ups and no protection? I recommended the ali piston with the pads - lasts longer than plastic ones. I like the set up as i said as it is reliable as i don't want to be opening it up every week. Iv done the mods and months down the line and many of games later its still running mint.

Just because you have never experienced this doesn't mean others haven't

Back to the OP eh?

Whoa, chill

many people choose not to use the ali piston and ali piston head due to them causing problems,

also high speed set ups can only cause breaks in the GB casing if the case is pot metal and is not set up correctly and properly installed,

richardy is just giving advise on a well hit nerve about new players wanting HIGH ROF, so chill. ..