gearbox jamming

kdouglas

hey guys, i posted this across on ASI, but just wondering if anyone here has any suggestions:

i decided about 1 month ago to upgrade the barrel in my cyma mp5 (cm027), so i bought a system 6.04mm precision barrel, because of the way the original cyma barrel/hopup is made, you need to cut the hopup section off the new barrel and fit a plastic hopup part over the barrel, did this and it all went grand, then went to use it at a skirmish and it was fine for a few test shots and then something broke and the gearbox was making horrible noises, needless to say it didnt get used for the rest of the day...

so a few days later i opened it up and it turns out i had somehow managed to strip about 1/4 of the gears from the sector gear, so i decided to go ahead and order a full tune kit, figured i may as well upgrade the bushings/cylinder/piston etc.. while i was fixing the gears

ive since fitted the FTK, and discovered that the motor is not powerful enough for the upgraded spring, so i re-installed the original spring until i get a new motor/battery. I also discovered the air nozzle doesnt quite fit and would require a bit of a trim to fit in, so for now i've put the original air nozzle and tappet plate back in.

everything worked fine, but it was firing terribly, bb's were dropping after about 30-40ft, i then decided to put the original barrel back in, just in case it was causing a problem.

now it's not firing at all, when i pull the trigger, i can hear the motor wind a little bit and then it jams, no bb's are fired at all, once it jams it doesnt do anything else. it sounds as if the gears are jamming just as the sector gear is about to start pulling the piston back, but when i open up the gearbox i cant see anything that might be causing it to jam.

anyone have any suggestions on what could be causing this or any pointers on troubleshooting the problem? (a clear gearbox would really be handy for this sort of thing!)

liamo333

You could take it apart and put it back together again. Did you shim it they are like little washers that go on the center rod of your gearbox.

Edit: the gearbox dissasembly vids explain about shimmimg.

kdouglas

i've taken it apart and put it back together about a dozen times now. :P

the gears are shimmed fine too, thought that might cause a problem alright, but there's no slop in the gears when the gearbox is closed and the gears are aligned fine.

liamo333

Have you timed the sector gear properly? Talk to this guy, he does repairs on airsoft guns. If you send your gearbox to him he will fix it. http://www.airsoftireland.com/forums/index.php?showuser=12#

kdouglas

yea, timed the sector gear, but whether or not that actually makes a difference is open to debate, as far as i can see the gears will sort themselves out anyway...

i put a post on ASI about this already, the surgeon's reply was bin the gun and buy a TM/CA etc... the full tune kit will never work according to him, it may take a bit of modifying, but i reckon i can make it work, i see no reason why it shouldnt

(i know, i know, he's probably been fixing gearbox's since before i even knew what airsoft was, but i see it as a challenge to make this work)