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CYMA 8mm Reinforced Gearbox for M4 M16 Series Airsoft AEG w/ MOSFET - Rear Wired

11 Customer Reviews

by Kenneth L. on 07/28/2015
"I made a previous review about it and I want to write another one for it. I officially had this gearbox for over a year. I had it as a spare gearbox since I "supposedly" got a newer one. Lo and Behold, I fried my new one and switched it back to this one.

From last time I chrono (my last game was in November 2014) it was shooting in between 378-381FPS with .20g. I chronoed sunday (7/26/15) and had the same fps on a M130. My gun is using the Madbull ultimate hopup with a 6.05 inner barrel and I can hit easily about 160ft using .25g. I gave it slightly more hop up and I was able to hit some at 102 yards. EVERYTHING is stock except the trigger contacts due to malfunction.
by Kenneth L. on 08/18/2014
"I got this about 2 weeks now, and had to wait to my upcoming event to have a true test. I was able to hit targets at least 50+ft with confirm hits, debatable around 80ft. Mine came with a ported cylinder shooting at 348fps, which it isnt that bad. However, if you want full power change it to a non-ported cylinder.

MOSFET is COMPLETELY different from the picture and its an APS MOSFET. Since its rear wired, you have to either use a stick battery or use a nun chuck for crane style stocks.

All in all, it performs really good, and I am satisfied with my purchase :D
by Jorge F. on 05/26/2014
"This is an excellent gearbox so far; although when I received it, it did have a slight problem. It would fire on its own! I was thinking of RMAing it, but I decided I didn't want to wait, so I opened it up, and something corrected itself automatically. I replaced a few parts (piston with metal teeth, bore up piston head and cylinder head and air nozzle with o-ring) and now it works great.

Pre shimmed / lubed
Spring guide notches are big (very helpful when assembling)
Strong tappet plate
Reinforced gearbox shell
Bearings (not ball bearings)
Gearbox screws (phillips heads, :P)
Easy takedown
Shoots hard (I haven't chronoed though)
Works very smoothly

Irritating things:
Putting the mosfet in the buffer tube
Wiring is a bit long, but it works
When assembling, it is hard to keep the trigger in place
Motor wire connectors aren't bent (I had to bend them myself)

Plastic piston (has one metal tooth) - replaced with metal- toothed piston
Air nozzle (no o-ring) - replaced with an air nozzle with o-ring

I am thinking about getting another one of these gearboxes :D
by Brad B. on 10/08/2013
"Some of the below review seem outdated mentioning what seem to be JG's older gearbox from 2010. I am sure evike gets these from JG with their orders of guns and these are the gearbox found inside a JG or Echo1 M4 carbine. It has 8mm bushing, my selector plate is black instead of yellow like the image and the mosfet has a nice hard casing to protect it from accidentals.

415 FPS out of the box on my new custom M4 running a stock JG 363mm barrel.

Over all, the item work as expected. Good strong parts and gearbox.

Great deal with a nice mosfet.
by jerry W. on 11/08/2012
"I dropped this gearbox in my jg m4,with a 9.6 battery,it punched half way through a boiling pot!!
Very good gearbox,i will be ordering another.
by Joel H. on 10/01/2012
"Amazing gearbox! Popped it into my wounded JG M16A4 and it has brought the gun back to life! The rate of fire is almost doubled compared to the original JG gearbox and sometimes it shoots so fast that the mag can't load a bb in time!!! (Which may sound bad but with a spring low-cap mag it would work just perfectly. It makes me happy though!) Anyway the only con is that the battery connector is mini-type and did not fit the battery I had so BEWARE! It was an easy fix by just soldering the old connector to the new wires. It's like putting an M16 into the Pack-A-Punch machine, it really strikes some fear into those radical Muslims!
by kyle c. on 12/04/2011
"Wonderful gear box. I am excited to put it in my echo1 stag 15 m4. With this kind of fps no one will be dishonest about being hit
by jared a. on 12/01/2010
"This gearbox is very good. i have taken it apart for a spring swap and had this chance to view the parts closely ( i will list the parts and quality at the end). I bought the gearbox for a g&g raider and had to customize the wires in order to makre it work. but afetr all of the cusomizing i have found it to be an excellant gearbox for the money.

m130 spring/good
bearing bushings (not ball bearing)/excellent
torque gears/excellent
ported cylinder/excellent
plastic cylinder head (one o-ring)/good
air nozzle (no o-ring)/good
plastic piston with full metal teeth (second tooth is not removed)/excellent
plastic piston head (not sure if it is ball bearing)/excellent
full metal spring guide (not ball bearing)/excellent
standard v2 tappet plate/good
standard trigger box/good
standard anti-reversal latch/good
Reinforced steel gearbox shell/excellent(only time will tell)
silver low resistance wiring/excellent

Only time will tell for the durability of this gearbox, please remember you may not get a gearbox that is as duable due to factory issues, so be ready for the liability. overall great gearbox.
by Steve J. on 08/06/2014
"I bought this gearbox to replace an old gearbox that had issues.
Taking it out of the box everything looked in order. I dropped it into my KA OA-15 M8 and tested the weapon. The first 10 shots seemed decent, that's where it goes bad. After about the 10th round bb's started flying everywhere, dropping, rising, no consistency whatsoever. 50 Ft shot group was about 15 feet wide. So I checked out my barrel / hopup to see if there was something wrong with the gun, nothing found. So I decided to look further into the new gearbox... I opened it up.

There was rust on the gearbox housing internally.... yup....
Bushings not Bearings
There was enough grease to drown the fonz (old reference?!)
The cylinder had almost no air seal / compression
The Air nozzle and piston had the quality of a cheap model car set.
Horrible Shimming
The spring had no... spring...

So I paid to basically get a set of spare parts, which I was able to use to create a decent gearbox when I cleaned it up, reshimmed, put in a new spring, piston, air nozzle and properly sealed the cylinder.

I gave it a two for two reasons -
First, at least all the parts were there?
Second, the wiring harness and mosfet were in excellent condition.
by Neal R. on 06/02/2014
"Just got mine today it looks different from the picture and has a aps MOSFET (decent) but only thing I'm having problems with is getting the motor to fit into it I think the MOSFET wiring and soldering is getting in the way of the motor gear and I can't get the cap on to suck the motor up in there but everything else seems fine haven't got to shoot due to motor not being able to fit good or something I got the G&P 120 motor might have been worth to have just gotten a whole new pro kit receiver motor gearbox and all for 120
by Jeffrey T. on 04/15/2012
"I am a retailer buying several thousand dollars of product from Evike and continue to do so. I have purchased 3 of these gear boxes. They all had issues with poor shimming and poor quality parts. I sold the bodies to customers who had bought the same gearbox and had the shell crack. Hopefully the next batch of gearboxes JG puts out are better. I give this particular gearbox and big thumbs down. Overall JG makes excellent quality products, I still buy a ton of JG products, just not this gearbox.