i need to upgrade a agm mp40 gearbox and put a high tourqe motor in place of the chinese one (WHICH MOTOR WOULD FIT?)
ive done ak47`s, mp5`s, a minimi, and a g3, but the agm mp 40 just dosnt work when i do it.
upon rebuilding it either fires a few shots then locks up,
or it just locks up right away
after 12 attempts at stripping/rebuilding im close to giving up.
ive just stretched the existing spring a bit.
then rebuilt it just to see if i did it right.
any advice much appeciated 
im not after tuneing it up with new pistons, nozzles, hops and such, just the chineese approach of a big fuck off spring , and to hell with the piston/cylinder leaks
also would a m150 spring bugger the gears and bushings already in it ???
any gearbox gurus that can offer advice please post
"Take that you rotton helping of strawberry flan!"
Joseph Porta to "strawberrys and cream", in the sven hassel book ,ogpu prison
The MP40 is pretty crap air loss wise ( through the hop unit & air seal nozzle ) but I have seen the standard motor crank a PDI 150% spring with no probs running a 8.4v 1400 mAh batt, I would change the piston head, spring guide & bushings, if it locks up it may need re shiming, due to the air loss though dont expect much more that 350fps,
Steve.D
steve, the motor seems to be sparking when i fire it, think the brushes are on the way out 
im not really arsed about air loss, just want the thing to turn the gearbox well
thanks mate
"Take that you rotton helping of strawberry flan!"
Joseph Porta to "strawberrys and cream", in the sven hassel book ,ogpu prison
Just change the barrel and hop... it makes a MASSIVE difference and keeps you below all the fps limits
its an mp40 gearbox and motor, but in my g41 rifle. it not in an mp40 case
its got a new psg 1 tightbore barrel, and new hop rubber in a ak47 hop unit.
its the gearbox itsself that the problem and the motor, stipping down again, it seems
"once more in to the gearbox my friends, once more"
Thanks guys
"Take that you rotton helping of strawberry flan!"
Joseph Porta to "strawberrys and cream", in the sven hassel book ,ogpu prison
I always thought the MP40 box was a heavily modified V3, just wondering if an AK motor might fit. As for the locking up I would try winding the gears by hand with the motor detached and the spring out, you may get a better idea why its locking when everything is movin at a slow speed...
thanks slick , never thought to try it without the spring
"Take that you rotton helping of strawberry flan!"
Joseph Porta to "strawberrys and cream", in the sven hassel book ,ogpu prison
