What size bushings

[UhhNoggy]

Does anyone know what size bushings are in the Cyma CM.517? I've tried googling but all the complete Cyma V2 gearbox's I find don't say the size of bushing just the material. 

If no-one knows how would I measure them?

 

[Sitting Duck]

8mm cross type

why do you need to know/change them ???

They are fine as they are - robust bushings

if you change gears, you can only fit the fastest @ 16:1 in there

unless you do some slight modification

(cut away a bit of the arc shape re-enforcement on numerous boxes)

careful modding with a dremmel
& say a couple of 20p size cutting discs....

https://www.youtube.com/watch?v=AE29OdDaRHg

Or taking a sledgehammer to crack a walnut method...

https://www.youtube.com/watch?v=6ZMLjBSNFu4

Spur gear "might" be a bit tight on some chunkier gear sets

but a 8mm bearing on top of spur should give you just enough free space

They are fine as they are - except for a possible tight spur gear on faster sets

(1 x 8mm bearing will suffice)

Gears are strong but bevel is a bit rough on meshing with most motors/pinions

hence if you can't find a nice bevel to mesh well will motor/pinion

then perhaps change the set if you are really fussed

unless you know what you are doing, I'd use the gun for what it is

sinking a load of money into a CM517 is not perhaps the wisest of ideas

do-able but still will be a £70 gun

If you enlighten us what your intentions are and what fps the gun is atm

then I can help you avoid spending too much money on this cheapo gun

(it's a good cheapo gun, but still a cheapo gun - so avoid going too nutz)

Some Cyma v2's like MP5 boxes ofa while back were 7mm & not re-enforced

V3 Cyma's might still be 7mm

Lately though the CM515 & 517's are 8mm cross type on re-enforced M4 V2's

(also slightly slightly different 8mm v2 M4 boxes used in P&J & higher metal M4 Cyma's)

But 8mm cross bushing is the answer to your question in your 517

http://translate.google.co.uk/translate?hl=en&sl=fr&u=http://www.france-airsoft.fr/forum/index.php%3Fshowtopic%3D198758&prev=search

To get the box out is a bit of challenge....

worth filing of these two stupid lugs just a bit to help remove/refit box

(Why they cast/put these extra lugs on there is beyond me)

 

[UhhNoggy]

The fps is 346 and the site limit is 350 so I'm happy with fps but I have found myself playing more semi than full auto. 

I was looking to put a high torque motor with a 12:1 gearset, shimming the new gears and using 8mm bearing bushings all SHS parts, my aim is just to achieve a faster trigger response while using semi auto, without looking into a Spectre (like you said I can fill the entire gun with new internals but it's still a £70 gun) 

The reason I'm happy to put a little money into the gun is because I doubt I can convince the wife to let me buy a £300 Ares or TM 

Hope this helps

 

[Sitting Duck]

I was looking at putting 8mm bearing bushings in and then fitting a shs 12:1 gearset in....is this not possible? 

Click to shrink...

Leave bushings - especially under spur gear

You have to grind away a bit on the arc to fit 14, 13, 12:1 gears in there

the inner teeth on the higher speed spur gear grind on the arc of side of gearbox

watch the two youtube vids I linked to

not just Cyma but many boxes that are re-enforced at the rear you need to do this

not hard, just more of a pain tbh on some Cyma, D-Boys, APS, some JG's I think....

they have this ARC thingy that gets in way

SRC have re-enforcement but not all re-enforced boxes have this protruding arc

that impedes on larger inner row of teeth from spur gear meshing to bevel gear

Edit: my bad, it is the inner ring of teeth that becomes larger & rubs on arc

This is the teeth that meshes to sector from spur not bevel gear (outer lower teeth)

Soz, you remove the arc as the spur's to sector teeth rub on arc

(not bevel as I originally said)

Other boxes, G&P, G&G, ICS (split box), VFC are not re-enforced

(so higher speed gears drop straight in)

If you don't grind away the extra material - then the lowest you can go is 16:1

(which is really 17.25:1 ratio in fact so less than 8% increase in speed to 18.65:1)

if you leave the stuff as, you could put a shs ht motor (cyma motor is slow 28tpa)

replace the tamiya with deans and you should be nearing say 19rps

avoid a high speed motor, the shs or RA motor will do fine

is the gun UK spec under 350fps ???

Only coz if it is 400fps you can use a metal rack piston, remove heavy spacer

& correct AoE plus SS a couple of teeth to bring her down to 350fps

(I've done that to hit 340fps on original spring)

 

[UhhNoggy]

I'm not quite sure with the UK spec thing you said, I bought it from patrol base and I'm just stating what they said (don't have a chrono)

Im not sure if you saw the edited post but RoF isn't a priority the only reason I'm thinking 12:1 is for a faster trigger response.

You have convinced me to leave the bushings alone 

 

[Sitting Duck]

I was looking to put a high torque motor with a 12:1 gearset, shimming the new gears and using 8mm bearing bushings all SHS parts, my aim is just to achieve a faster trigger response while using semi auto, without looking into a Spectre (like you said I can fill the entire gun with new internals but it's still a £70 gun) 

The reason I'm happy to put a little money into the gun is because I doubt I can convince the wife to let me buy a £300 Ares or TM 

Hope this helps

Click to shrink...

Ahh OK, the gun is UK spec

Drop in a SHS RA HT motor...

https://www.ak2m4.co.uk/ra-high-torque-motor-long

(move ya ar$e as they do sell out and take 2/3 weeks to restock)

Chuck that in there, fingers crossed the motor height will roughly ok

add a small bit of grease to new motor pinion if possible

(might need to adjust it a smidge but should be sort of ok)

Really you should check/adjust shimming blah blah blah...

But that will do you proud.....

In reality you should rip box open do AoE, check shims and stuff

but you "could" just drop that in as is for a while....

6/12 months later then service and tweak stuff inside

Or if guns busts sooner rather than later

Or chuck the gun and buy better

(it's a toss up when to keep throwing money into this gun or just move up

 

[Sitting Duck]

I'm not quite sure with the UK spec thing you said, I bought it from patrol base and I'm just stating what they said (don't have a chrono)

Im not sure if you saw the edited post but RoF isn't a priority the only reason I'm thinking 12:1 is for a faster trigger response.

You have convinced me to leave the bushings alone 

Click to shrink...

Drop the better motor in there if you want a bit more zest

should go from say 12 to about 18rps and change to deans than tamiya

that connector will also give you 1rps to 1.5rps increase too

Look if gun busts, you can fix it cheaply or cut your losses

it is easy to fix up, the box is sound (bit qwirky v2 box with a v3 spring guide etc...)

but it is a strong box, the receiver is a bit brittle in cold weather

a cheapo clone of a G&G Raider - it s a medium length Raider 300mm barrel

(G&G do a short 233 or long 357 - should have done a 300mm medium like cyma imho)

the receiver is a bit weak, the buffer tube is plastic, the mag catch is plastic

so it isn't as robust as G&G receiver but if you are careful it should last

if it busts badly, you lost little and take new motor into next gun

you could replace loads of bits if you wish

but just keep it sensible than sink another £75/£100 into it

look into deans & motor

google youtube for deans connectors tweaks

CUT ONE WIRE AT A TIME !!!! (cut, fit shrink tube, solder, insulate & move on)

A short by cutting two wires together at battery will make you $HIT YOURSELF !!!!

 

[UhhNoggy]

Drop the better motor in there if you want a bit more zest

should go from say 12 to about 18rps and change to deans than tamiya

that connector will also give you 1rps to 1.5rps increase too

Look if gun busts, you can fix it cheaply or cut your losses

it is easy to fix up, the box is sound (bit qwirky v2 box with a v3 spring guide etc...)

but it is a strong box, the receiver is a bit brittle in cold weather

a cheapo clone of a G&G Raider - it s a medium length Raider 300mm barrel

(G&G do a short 233 or long 357 - should have done a 300mm medium like cyma imho)

the receiver is a bit weak, the buffer tube is plastic, the mag catch is plastic

so it isn't as robust as G&G receiver but if you are careful it should last

if it busts badly, you lost little and take new motor into next gun

you could replace loads of bits if you wish

but just keep it sensible than sink another £75/£100 into it

look into deans & motor

google youtube for deans connectors tweaks

CUT ONE WIRE AT A TIME !!!!

A short by cutting two wires together at battery will make you $HIT YOURSELF !!!!

Click to shrink...

Well that's fine by me! I'll go for the HT motor and yea I'll most probably get some deans connectors aswel. Thanks for the help!!!