Pre-Built Gearbox or Build your own?

[kylescave]

So i have found a replacement gearbox for my M4 https://www.airsoftworld.net/kwa-version-2-gearbox.html

I want to use this with a Lonex A2 motor. 

Would this be complete over kill?

The KWA Gearbox is £95, i could get a cheaper SHS Gearbox for £50

How would this perform? Would it be way too powerful to use on site? 

Any help and advice would be helpful. 

I myself love to tinker. so building my own would not bother me.

Just want to know what options are best.

Many thanks.

 

[BigStew]

What gun is this replacement gearbox going into? Even thought they are version 2 gearboxes they are not exactly the same and may require modification to fit. Performance wise don't known about KWA SHS make reasonably good quality parts. If you are buying them in the uk both should be site legal but you can't say for sure until you fit them and chrono them.

 

[Speedbird_666]

What gun is this replacement gearbox going into? Even thought they are version 2 gearboxes they are not exactly the same and may require modification to fit.

This.

Also, KWA tend to use proprietary parts in their GBs (tappet/nozzle), so upgrading/repairing later might be trickier.

I would get a cheap GB for now to play around with - you can still upgrade the tits out of it, but if you fuck up (and you will to start with) it's won't be so painful financially.

 

[kylescave]

What gun is this replacement gearbox going into? Even thought they are version 2 gearboxes they are not exactly the same and may require modification to fit. Performance wise don't known about KWA SHS make reasonably good quality parts. If you are buying them in the uk both should be site legal but you can't say for sure until you fit them and chrono them.

Its going into my M4. I do not know the make/brand. i think i am going to go for the SHS cheaper option. And decide what to do at a later date. Because i would like to upgrade the tits outta my gun and fit a mosfet as well. Any upgrade kits would be much appreciated.

Also my original gearbox gears say G&P. and these gearboxes seem to be around the £140 mark. so i assume i would be better off trying to rebuild this on in the future and use that?

 

[BigStew]

Its going into my M4. I do not know the make/brand. i think i am going to go for the SHS cheaper option. And decide what to do at a later date. Because i would like to upgrade the tits outta my gun and fit a mosfet as well. Any upgrade kits would be much appreciated.

Also my original gearbox gears say G&P. and these gearboxes seem to be around the £140 mark. so i assume i would be better off trying to rebuild this on in the future and use that?

Unless the gearbox casing is damaged it maybe worth looking up a YouTube guide a opening the gearbox up and trying to fix it. What's actually wrong just to make sure it actually is the gearbox?

 

[kylescave]

The casing is not damaged, and i will 100% try and rebuild it. Im 99% sure i burnt the trigger out using a powerful battery. so i need to replace that. However i was thinking of upgrading parts. But im not sure what parts would be an upgrade. Ive been told my gearset is pretty good. so was just considering a piston with two seals to give it a bit more compression.

This is what i have...

View attachment 76613

View attachment 76614

View attachment 76615

View attachment 76616

i Could also have burnt the motor out, however it does seem to be working okay. However i was looking at a Lonex A2.

Any ideas?/thoughts?

 

[ak2m4]

Buying a new complete gearbox doesn't always solve your problems, best to work with the existing shell.  From the pics looks like you just need a new piston, piston head, and selector plate.  You need to test your cylinder head and nozzle.  Grab some metal and silicone lube, some shims.

Never used a Lonex A2 before, my choice would be a SHS high torque motor but there's plenty of others out there. 

 

[Adolf Hamster]

tbh there doesn't appear to be anything wrong with that gearbox internally that a clean, regrease and the usual air seal/shimming/aoe checks wouldn't solve.

have a look here for a general idea of things to be looking for:





trigger contacts fouling up is very common, a powerful battery will make it happen faster/risk burning them through, but it'll happen to any standard wired gun if used long enough.

the solution to that is a mosfet, either something basic (like the nanoasr) will just protect the contacts or something fancy (eg the warfet) will give you the fancy precocking etc.

Buying a new complete gearbox doesn't always solve your problems, best to work with the existing shell.  From the pics looks like you just need a new piston, piston head, and selector plate.  You need to test your cylinder head and nozzle.  Grab some metal and silicone lube, some shims.

^pretty much what i'd be thinking of doing, also all those things are conveniently available from https://www.ak2m4.co.uk, and no he's not paying me to plug that link.

it really depends on your priority, wether you just want to get it working or if you want to get her up to a good shooter.

that piston isn't in the worst condition, definately usable but i'd probably look to swap it out anyway, but then i'm obsessed with accuracy so anything less than perfect air seal is a no-go for me.

also perhaps consider treating her to a nice zci 6.02, ml macaron and omega nub.

assuming the gun it came out of is also a g&p then you're looking at a pretty sweet m4 all things considered.

 

[kylescave]

tbh there doesn't appear to be anything wrong with that gearbox internally that a clean, regrease and the usual air seal/shimming/aoe checks wouldn't solve.

have a look here for a general idea of things to be looking for:





trigger contacts fouling up is very common, a powerful battery will make it happen faster/risk burning them through, but it'll happen to any standard wired gun if used long enough.

the solution to that is a mosfet, either something basic (like the nanoasr) will just protect the contacts or something fancy (eg the warfet) will give you the fancy precocking etc.

^pretty much what i'd be thinking of doing, also all those things are conveniently available from https://www.ak2m4.co.uk, and no he's not paying me to plug that link.

it really depends on your priority, wether you just want to get it working or if you want to get her up to a good shooter.

that piston isn't in the worst condition, definately usable but i'd probably look to swap it out anyway, but then i'm obsessed with accuracy so anything less than perfect air seal is a no-go for me.

also perhaps consider treating her to a nice zci 6.02, ml macaron and omega nub.

assuming the gun it came out of is also a g&p then you're looking at a pretty sweet m4 all things considered.

Is there a way of telling if the gun is a G and P? The hop up dust cover does not close so i am assuming the gearbox has been changed before, because i cant imagine it would come out the factory like this. I have no clue of the gun make because it was given to me years ago but i was told it was expensive. Also could you give me a piston that is compatible. because im struggling to find one with the same amount of teeth. or does that not matter?

I am a noob t this. But i am eager to learn how to upgrade and rebuild.

Many thanks!!!! 

 

[Adolf Hamster]

Is there a way of telling if the gun is a G and P? The hop up dust cover does not close so i am assuming the gearbox has been changed before, because i cant imagine it would come out the factory like this.

not really familiar enough with the g&p recievers to offer any tips there, it's entirely possible the box has been pulled before but the same box reinstalled, broken dust covers are a very common thing for the ar platform, could even be as simple as pulling the upper to clear a jam from the hop could cause that.

if you pop some pics of the rest of the gun/reciever someone might be able to chime in recognising it.

Also could you give me a piston that is compatible. because im struggling to find one with the same amount of teeth. or does that not matter? 

the tricky one with piston teeth is often they can have the first tooth removed for engagement.

usually your "standard" is a 15 tooth (https://www.ak2m4.co.uk/internal-parts/pistons/ra-15-tooth-piston), however with the first pickup tooth removed you end up with a 14 tooth (https://www.ak2m4.co.uk/internal-parts/pistons/rocket-14-5-tooth-full-piston)

you can also get the likes of the 14.5 tooth which has only half of the first tooth removed.

that's not to be confused with short-stroking, where teeth from the front of the piston are removed to reduce the distance it travels (teeth are also removed from the sector gear), that's usually done for high speed builds to prevent premature engagement (when the sector spins so fast it goes full circle before the piston has moved all the way forwards).

in general they tend to be pretty standard, although as with all things airsoft sometimes you'll get one that's slightly too wide for a given gearbox which ends up tight. my go-to would be the likes of the shs 14 tooth.

the one that might be tricky is the piston head, i have it rattling around somewhere in my memory that the g&p's are a different bore to standard? it's been a while since i've worked on one so i could be thinking of another brand.

 

[Shaydee]

Is there a way of telling if the gun is a G and P? The hop up dust cover does not close so i am assuming the gearbox has been changed before, because i cant imagine it would come out the factory like this.

Are you talking about the actual dust cover or the mock bolt? G&P dust covers don't close as standard from what I've read and if the receiver I've got has the original one then I can confirm that is the case. As for the gearbox I have no idea if that's G&P or not as I bought my receiver second hand, I can confirm that an E&C box seems to fit without issue however.
View attachment 76647

 

[Iceni]

Im 99% sure i burnt the trigger out using a powerful battery

Probably not, unless you stuck a huge battery in it like a 6S.

Your original contacts look decent TBF Just the wires are a little chewed in places.

The reason it probably wasn't shooting is the Selector plate. I linked to that part in the other thread you started without all these little extra nuggets of information. There's a good chance that £5 part would of made the gun shoot again without needing anything else, but you'd already stripped the gearbox. The break on that part would mean the gun couldn't select any fire mode other than the safe position.
 

 

[Sneaky]

I would personally do a rebuild, you said you like to tinker!  At least that way you know what is going on witht eh gearbox and parts.  

Also there is the satification of doing it and getting it working.

 

[Lozart]

The reason it probably wasn't shooting is the Selector plate. I linked to that part in the other thread you started without all these little extra nuggets of information. There's a good chance that £5 part would of made the gun shoot again without needing anything else, but you'd already stripped the gearbox. The break on that part would mean the gun couldn't select any fire mode other than the safe position.
 

You're right that it is most likely the selector plate that is causing the non function, but having stripped it down he can now see that the piston and head have seen better days and that the gears have been rubbing together. Now he can fix the selector plate AND improve the rest of the performance.

 

[kylescave]

So i have only just realised that a mock bolt exists. I've never had one on my gun since it was given to me. Does anyone know if i can just buy any one or if it need to be a specific one for my upper. From what i can see most of them seem to be very similar if not the same.

 

[Lozart]

So i have only just realised that a mock bolt exists. I've never had one on my gun since it was given to me. Does anyone know if i can just buy any one or if it need to be a specific one for my upper. From what i can see most of them seem to be very similar if not the same.

They all look the same but there are some differences. If you don't buy an original one I can almost guarantee that it won't quite work right without some kinetic engineering.