Bloody CM16

[adazrambo]

Hi All,

 

I acquired a G&G CM16 from a friend around about a year ago, took it for it's first test today at local skirmish and this gun is plagued with problems.

 

Firstly it seemed severely underpowered, when chrono'd one of the guys said it was around 150fps below site limit which is 350, not only that but the range was probably around 30 feet at the most and i was having to lift the gun up to compensate.

 

Secondly, around about an hour in the handle/trigger became awfully hot, almost to the point of being unable to touch it, eventually the fuse blew and it melted the casing around it so i bypassed this by rigging it directly to the battery.

 

When speaking to some of the regulars at site they thought it may be because the motor isn't seated properly or something. Any of you guys had similar before?

 

Debating weather it's worth getting fixed or biting the bullet and buying a new gun.

[cyrexx]

I would recommend having a go at fixing it, it will be a good learning experience

 

The FPS loss is going to be either a compression issue or the nozzle is not engaging properly.

 

If the handle is getting hot it probably means the motor height needs adjusting or/and it could need re-shimming.

 

Has the previous owner been taking the gun apart?

[adazrambo]

I would recommend having a go at fixing it, it will be a good learning experience

 

The FPS loss is going to be either a compression issue or the nozzle is not engaging properly.

 

If the handle is getting hot it probably means the motor height needs adjusting or/and it could need re-shimming.

 

Has the previous owner been taking the gun apart?

 

Ok thanks, so assume a new spring will be needed for compression issue?

 

Ah yes! that's what one of the fellas said now you've reminded me, how would I adjust motor height?

 

I'd say it's likely he's been tinkering with it!

 

Cheers for help.

 

Adam

[Hef Legend]

New nozzle

Possibly Spring

Some Orings, for the nozzle and piston

[cyrexx]

https://www.youtube.com/watch?v=FlV5peGEnag This is how you test how good the compression is. i

 

If the compression is fine try this method https://www.youtube.com/watch?v=MFnUjxdiXuU.

 

if that seems ok, watch this https://www.youtube.com/watch?v=jj0mM8A2C3A# to find out if the nozzleand tappet is ok. The video also shows how to change the motor height.

 

If the nozzle is fine then it is probably the spring that needs changing.

[adazrambo]

Great - thanks for all the replies i'll give them a try!

[Sitting Duck]

 

Ok thanks, so assume a new spring will be needed for compression issue?

 

Ah yes! that's what one of the fellas said now you've reminded me, how would I adjust motor height?

 

I'd say it's likely he's been tinkering with it!

 

Cheers for help.

 

Adam

 

sounds like one of my first SRC's i "tried" to tinker with - lol

tinkering with guns - yeah bit of a learning curve that one - still learning btw like us all

 

to service a gun is actually really cheap unless major failures but still not end of world

(at worse a new gearbox - £40-ish)

but often like was said:

 

spring - £5, shs m100 or element m105

seals - not the ocean/zoo kind - they are tricky to maintain

piston o-rings - ebay# 271015542147 - very expensive, will have to save up a couple of quid to buy some more soon

AoE neoprene pads - yes sorbothane is best but for most low to medium build guns neoprene will suffice - ebay # 250981193606 - M4 size

(2 usually required to correct AoE - G&G should have removed 2nd tooth so maybe a slight shave/file to reduce slightly 3rd tooth)

 

O-ring M4 nozzle - £5-ish and should be fitted - red shs is a good decent one

new M4 or V2 cylinder head £8 aprox give or take a quid or two

(can use ptfe tape wrapped around the old head - but me I'd get a double o-ring head and maybe tape if needed for best perfect seal)

 

pack of shims - probably really bollox'd and bevel shimmed too low by previous owner - £4-ish

 

Gears - should be fine, don't try for mega high speed ones unless you upgrade motor - good gears n motor will cost ya £50 aprox

plus where do you start & stop - if doing that gear/motor then you gotta fit mosfet & rewire n crap too

 

I'm trying to give you a brief - pah when is anything reply of mine short n brief - lol

giving you a basic easy / cheap idea to service & get her back running again to last a while.....

 

Bearing spring guide - better than piston bearings but bearing spring guide is gonna be maybe something to leave for next time with motor/gears/fet options

Unless you wanna just go the whole hog - which tbh I'd advise doing it in gradual stages

 

a rough cheap list of bits to service it with, unless gears or tappet plate is bollox'd

black stock piston, tappet plate, cylinder will be fine etc......

 

only other thing as gun was s/hand is maybe get some 8mm bushings/bearings as the bronzey G&G's do wear a little quicker than steel bushings

 

hopefully wiring is ok and motor hasn't burnt out etc... - but that cheap list of bits will do ya proud

it is all in the fitting - especially shimming and little grease up - so read up a bit

a little time and it is just a like building a kids basic little lego kit

though at first when it don't go according to plan - it seems like Death Star or Millennium Falcon mofo

(yeah I'd take a gearbox anyday than another christmas/new year wasted of my life doing that f*cking falcon mofo with kids)

 

as long as it is just a normal CM non-blowback gearbox there isn't much inside a normal box really

[Sitting Duck]

Blimey - did I just type all that crap - probably scared the poor sod off

now he thinks - yeah right am I gonna read all that $hit - I'll just get a new gun

[BigAl]

Hmm buy a gun stick it in cupboard for year and take it out straight to a skirmish, good plan. lol

 

Firstly you say you bought it from a friend so have you spoken ti him about it. He may be able to help you fix it or point you in the right direction.

 

If that doesn't work try asking around at the site, i'm sure there be some kind sole there than can help you out for cost of parts, perhaps buy him a pint.

[adazrambo]

Cheers Sitting Duck! Covered all bases there! Decided to have a little play around.. Here he goes..

 

Well you lot are going to laugh, absolute amateur hour but I've dismantled down to gearbox to see how things work and I attached image left? Any ideas?

[adazrambo]

Couldn't upload. Number 32 on exploded diagram.

 

http://guay2.com/web/drawings/gb/CM16-box.pdf

[Sitting Duck]

Couldn't upload. Number 32 on exploded diagram.

 

http://guay2.com/web/drawings/gb/CM16-box.pdf

 

wtf is this - painting by numbers - AR latch - the spring to be exact

had one break in a cm18 when pushing her on 11.1v

oops tell a lie it was the latch itself that cracked but spring was like a pube

 

element/shs ar latch n spring will sort it but you need to investigate fps drop

 

upload to imgur and copy/paste link

 

I love the pdf title - CM 16 Gear Box EXPLODE - yup often they do just that opening them first time around

 

mr cm18 clonked and then the AR didn't work at all really, and piston kept rolling back if slightly compressed

thought it was a mangle pubic hair spring but as I removed it - the latch just cracked in two also

only had this once so unless a bad batch or bad luck - hasn't happened since

 

still you have pi$$ poor seals or fps though - but yup could of played a part in gearbox lockup

"might" be other issues related so remove spring and spring off tappet plate and see how all the bits turn inside

 

if all looks ok the remove cylinder with tappet & piston etc.....

close up box - holding by hand is ok for first initial test - spin gears trying to get finger in cylinder window and flick the sector

check for major snagging - like a tiny dot of plastic between teeth of gears

there will be loads of play - half that amount once closed up which is a proper check you do afterwards

DO NOT OVERTIGHTEN SCREWS - I say using a thumb and index finger as tight as you feel you can do it up is plenty

using a clenched fist to tighten box will just strip the fine threads on gearbox casing quickly

 

basically you need to ensure nothing is catching/locking up

also check wiring - hopefully just the AR caused a jam and no real damage

then sort out your seals - not the zoo type

 

bevel should have one thinest shim on top or nowt if using thick bushings

(this is a rough guideline only but so many shim it too low and tbh you have to use thin bearings and no shim to shim too high imho)

read up ffs on shimming - you may not master it for a long while - I'm still far from what I call pretty good at it compare to real techy's

but you will understand the basics of spacing/stacking them gears to get it nigh on as best as possible

 

there is loads of crap to check and a few replacement bits

check how much play is in the bronzey bushings - if s/hand there could be a bit of play by now in the holes where gear shafts run

so replacements "may" need to be considered if excess movement.

replacing these will deffo through out the shimming so you gotta understand it all a bit

 

then look at them seals n stuff - clean up dirty gunky grease - bit of new lithium grease on gears/bushings/shafts

silicone grease on piston's o-ring once sorted with new one etc......

 

take your time and try not to lose any tiny springs n such

 

few dry runs closing up box with out spring - then hopefully she will be sorted soon to put all back together

you did keep them bits safe and take a few pics btw...