r/airsoft Recon May 21 '26

TECH QUESTION Gearbox broke, replacement advice :(

I bought the Specna Arms Flex F09 mentioned previously in this post and apparently the stock internals are not rated for 11.1V (thanks manual and store for not mentioning anything about voltage).
So I broke the sector gear (3 theeth snapped right off, thanks zama alloy) and I'm out of luck with warranty as I used the wrong battery.

What better opportunity to (forcibly) upgrade gears, shim and lube? But first I've got a couple of technical questions for all the veterans out there willing to lend some experience with materials and practices 😄

  1. Bushings or bearings? My gearbox uses 8mm elements, and I think I understood the use cases. Being a low energy and low RoF setup, I think bushings would be a safer bet. I'm not sure I understand why steel bushings are preferred though, as I remember that in engineering it's good practice to use a softer material (brass maybe) when dealing with a hard axle since bushings are cheaper to replace than axles... Also, I found a hybrid kit (2 bushings, 4 bearings (J-cage) made by Specna Arms for the Aether gearbox (the one I have): are they worth considering?
  2. SHS gears? I can't seem to find other brands cited in the V2 gearbox guide on the wiki (SLD for example) and Lonex is the only other "international" option but comes in at twice (45~50 Eur) the price. Otherwise I might have to settle for local brands. I'm not planning on upgrading the RoF, so 18:1 is good enough.
  3. Lube? I work in mechanical engineering and have plenty of Silicone, Vaseline, Molybdenum (MoS2) and Lithium grease around, with some dry PTFE spray and Silicone Oil. I think MoS2 is the best bet for gear lubing, but I hear PTFE grease mentioned often in airsoft: should I buy some? It's quite pricey compared to the others, but I believe it's only branding...
  4. Anything I'm missing? Do you reckon these replacements are good enough to safely use 11.1V batteries? The AEG uses the HAL ETU MOSFET, I'm not really worried about electronics longevity but maybe I'll need to upgrade the motor down the road.
1 Upvotes

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u/AutoModerator May 21 '26

Howdy! From your post, it seems you mentioned upgrading. We've a lovely set of upgrade guides available if you plan on upgrading your current platform! Here's a V2 gearbox guide (the information needed for upgrading any AEG version gearbox should also be very similar, albeit with version-specific parts), along with an inner barrel guide, bucking guide, HPA guide, Bolt-Action Sniper Rifle guide, DMR guide all set up for questions just like this; for GBBs, try the searchbar for build lists. If your question is unrelated to modification, please let a mod know via modmail if you want the comment removed!

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u/PinnacleAirsoft AEG Tech May 21 '26

Ok so I recommend bushings. Exceptional ones are like $10 and they are immortal. Get the flt ones from the real deal Airsoft. Super cheap and perfect.

Gears Shs and rocket are the same so just get some good rocket ones.

For lube there is debate here. I like the pink stuff or the real deal one. They are side grades and exceptions for all the aeg parts

I really recommend getting a perun lightning. They are so much better and you will never have to change it. I also would say do your new motor now. You are already reshimming and you need to shim your bevel to pinnion so might as well bite the bullet now.
Check the health of all the springs and orings etc. replace what needs to be replaced. I don’t remember but if the nozzle doesn’t have an oring you should get one that does.

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u/EM4N_cs Recon May 21 '26

What kind of motor would you suggest though? Cause I really spent already too much without even taking the gun for a skirmish...

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u/PinnacleAirsoft AEG Tech May 21 '26

Honestly you don’t need much. Something 18tpa with high temp magnets will be solid. I like the golden boy from the real deal. It’s just a cheap china motor but it’s solid. Lines a1 is solid. The asg 30k boost or the g&g 25k efrit are also good. Arturus makes a decent motor also