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- Sep 2, 2014
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The CYMA 02 AK gearbox is now in my AK12. Theoretically, with a bit of fiddling, you could just drop it straight in, put it back together and off you go, although in practice it required a bit more effort. So for anyone contemplating doing a similar thing, here's how mine went:
The gearbox does drop straight in place, however, the wires have to reach spring loaded terminals at the rear of the receiver which connect to the terminals on the stock housing the battery. Those wires can easily foul the gearbox and prevent it from sitting properly in place, so I made that a little bit easier by shaving two small channels into the moulded runners on the inside of the left half of the main body of the rifle, to give the wires a bit of room to easily pass under the gearbox housing. The plastic was easily shaved out using a broad chisel blade.
The CYMA gearbox comes with a Tamiya plug on it, so I cut that off, stripped some of the insulation off the remaining wire, cut the two terminals off the old gearbox, leaving a bit of wire attached to those, and then simply joined those to the wires on the CYMA gearbox then soldered the wire twists and covered them with insulation.
Upon putting the gun back together, I discovered a minor issue arises when switching the CYMA 02 gearbox for the original plastic one: When you slide the pistol grip over the motor section of the gearbox, you find that the countersunk hole for the screw on the bottom of the pistol grip (where the motor height is adjusted) is approximately four millimeters further to the rear than the threaded hole on the bottom of the CYMA gearbox. You can tilt the pistol grip enough to get the screw to go in and fasten up, but doing that would mean the pistol grip would not sit nicely against the lower receiver, so what I've done, is fill the screw hole (with Milliput) and then re-drill a new hole for the screw a bit further forward, which means the pistol grip does now seat properly.
So, not quite a 'drop in' modification, but not very far off it, and easy enough for anyone to do with some very basic tools. I've not chrono'd the thing (will try to do so this week) but it does shoot very hot now and if I put a better barrel and hop up on it (which I probably shall) then it would be a very very good rifle indeed, and it is already pretty good now even with the original barrel and hop up unit.
So, total cost thus far for an AK12 with decent internals: 69.99 for the gun, 40.13 for the gearbox adds up to 110.12. If it was any other sort of widely available rifle type, I'd say it was not worth the effort of doing it, but since it is the only AK12 you can get, and you want one that you could reliably skirmish with, then it is worth doing this little project, as sticking a decent barrel and hop on it would still have the thing probably costing less than 150 quid.
The gearbox does drop straight in place, however, the wires have to reach spring loaded terminals at the rear of the receiver which connect to the terminals on the stock housing the battery. Those wires can easily foul the gearbox and prevent it from sitting properly in place, so I made that a little bit easier by shaving two small channels into the moulded runners on the inside of the left half of the main body of the rifle, to give the wires a bit of room to easily pass under the gearbox housing. The plastic was easily shaved out using a broad chisel blade.
The CYMA gearbox comes with a Tamiya plug on it, so I cut that off, stripped some of the insulation off the remaining wire, cut the two terminals off the old gearbox, leaving a bit of wire attached to those, and then simply joined those to the wires on the CYMA gearbox then soldered the wire twists and covered them with insulation.
Upon putting the gun back together, I discovered a minor issue arises when switching the CYMA 02 gearbox for the original plastic one: When you slide the pistol grip over the motor section of the gearbox, you find that the countersunk hole for the screw on the bottom of the pistol grip (where the motor height is adjusted) is approximately four millimeters further to the rear than the threaded hole on the bottom of the CYMA gearbox. You can tilt the pistol grip enough to get the screw to go in and fasten up, but doing that would mean the pistol grip would not sit nicely against the lower receiver, so what I've done, is fill the screw hole (with Milliput) and then re-drill a new hole for the screw a bit further forward, which means the pistol grip does now seat properly.
So, not quite a 'drop in' modification, but not very far off it, and easy enough for anyone to do with some very basic tools. I've not chrono'd the thing (will try to do so this week) but it does shoot very hot now and if I put a better barrel and hop up on it (which I probably shall) then it would be a very very good rifle indeed, and it is already pretty good now even with the original barrel and hop up unit.
So, total cost thus far for an AK12 with decent internals: 69.99 for the gun, 40.13 for the gearbox adds up to 110.12. If it was any other sort of widely available rifle type, I'd say it was not worth the effort of doing it, but since it is the only AK12 you can get, and you want one that you could reliably skirmish with, then it is worth doing this little project, as sticking a decent barrel and hop on it would still have the thing probably costing less than 150 quid.
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but you've done a great job mate!
