M4 V2 gearbox issues

[smokebelch]

Guys,

Im completely stumped and in need of some serious assistance.

I decided after much research and watching vids that I'd have a stab at building a high speed v2 gearbox, and this is where my problems begin!

I've purchased the following:

ASG Ultimate Cylinder

Madbull Alien Orange piston

ASG Ultimate Piston Head

ASG Ultimate Cylinder Head

SHS 13:1 gear set

SHS Air Nozzle

SHS Speed Motor

SHS Delay Chip

Assorted shims

I got the gears all shimmed ok (least it looked like they were, going in everything I've seen/ watched)

Assembled the rest of the gearbox with no issues.

First time I fired it up, it blew the fuse.

Opened it back up, couldn't see anything out of place.

Put different fuse in and tried it again and it fired ok.......for about 40 cycles then blew the fuse again.

Opened it up again and still cant see anything obvious, BUT noticed the wires from the battery were VERY hot! (has silver wire running throughout)

Tried for 3rd and final time, fired for a few times then stopped and smoke started coming out of my lipo 7.4v 2000mah!!!! at this point I'd ran out of fuses anyway so cant proceed until tomorrow when I get some more, but in the meantime I thought I'd ask you guys if you have ideas as Im stumped!

Any advice would be greatly recieved, but please no flaming, I admit Im a complete noob to custom internal work

Thanks in advance

 

[AK47frizzle]

Check the wiring, it may have a short circuit

 

[Mack]

Could be that the motor is trying to draw more current than normal, this could be the shimming not right or motor height not set properly. Or could be something simpiler like a short or wrong amp fuse for the battery

 

[Adam3088]

When it was firing what did it sound like, very whiny? Also if you remove the motor, cylinder and piston, screw the gearbox together and try to turn the gears, do they spin freely?

If you haven't already, probably want to dispose of that battery, sounds like it's fried..

 

[lazareth1]

When it was firing what did it sound like, very whiny? Also if you remove the motor, cylinder and piston, screw the gearbox together and try to turn the gears, do they spin freely?

If you haven't already, probably want to dispose of that battery, sounds like it's fried..

This ^. Check everything is running smoothly and the gears spin freely.

 

[Sitting Duck]

Guys,

I've purchased the following:

ASG Ultimate Cylinder

Madbull Alien Orange piston

ASG Ultimate Piston Head

ASG Ultimate Cylinder Head

SHS 13:1 gear set

SHS Air Nozzle

SHS Speed Motor

SHS Delay Chip

Assorted shims

your piston I think is full metal - presume you did aoe

your gears are 13:1

you motor is high speed shs perhaps ???

now if you got that stuff all fitted together correctly you could hit 30rps

with a full metal tooth piston there is no weak point to shred off plastic teeth

So if Pre Engagement starts to occur - which I reckon at 30rps it could your box will either:

smash f*ck out of everything - or blow the fuse

if using a m90 or m100 spring then it is very likely to get to 30rps or quite near @ say 25 to 27rps

but bear in mind the speed motors from shs do cycle a smidge faster than the fast torque motors

so think 27rps is possible without needing thick mofo wires in there

(this may be reduced if still using small tamiya and no fet etc.... but still that build is a quick build even with 7.4v)

My guess if the above is not applying just yet is bevel gear shimmed too low, piston binding in box

or something else putting extra strain on motor to blow fuse.....

if this was your first build then I would suggest you put back the stock gears and get her running ok again

then later on if you want to go quicker read up a bit on mosfet rewire deans and shortstroking perhaps

13:1 gears can make a gun cycle very quickly and over 25rps she can start to double fire...

and past this on a full stroke piston and m90/100 springs you can get PE

do builds/upgrades in stages - faster builds need a little more thought rather than just drop this n that go faster stuff in there

I know this as I have boned numerous guns by going mental without doing my homework properly

and pushing boxes too fast - way too fast many many times

(plus first builds I did were a disaster as well - still learning btw)

 

[smokebelch]

many many thanks for your replies guys.

I suspect the cause of the first issue was a short somewhere.

So, after a late night last night, swearing, soldering, rewiring shimming, swearing etc, finally got the gun running.

Trouble was it would lock up very soon after firing.

Checked everything, piston moving freely, gears spinning freely with no side to side play (so assume shimmed ok?)

So, put the original motor back in and all seemed well, so I boxed it back up. Still had a higher ROF than originally and I've learnt something along the way.

Got the gun reassembled.......misfeeding massively!!!!!!.......(had installed a delay chip too, forgot to say)

Anyway, long story short I've ended up taking in somewhere, and upon talking to one of the techs it turns out I shouldnt have been trying to run the 13:1 gears and high speed motor together anyway.

After a long conversation he's going to put 18:1 gears in, stick with the high speed motor, do a proper shim job, install prowin hop up with prometheus rubber, tight bore barrel, put in mosfet and anything else it needs to get it up to scratch in terms of speed and reliability.

Been a steep (and relatively exspensive) learning curve. But fully take on board the comments about doing a build in stages, will definately bare that in mind next time (this wont have put me off lol)

Thanks again guys, your advice was very much appreciated.

 

[Sitting Duck]

shimming needs a smidge of side to side play or the gears will bind/snag

getting them placed correctly takes time/patience and everybox is a little different to others

had a mp5 that still sounded like 2 cats killing each other in there no matter what I did

it is still a little smidge schreechy in my book but deffo got some play and now using a lightly used G&G gear set in there

I'm still learning new crap on every box

my first few builds had the bevel gear a bit too low - spun lovely

but when motor wound in it was forcing bevel real tight against the bush/bearing on top

not quite schreechy but motor/wire everything was getting warm-hot quickly from strain

read this - a lot of info there and you don't need to go nutz to get you gun running a bit faster

http://www.airsoftsociety.com/forums/f10/legacys-guide-building-high-speed-aeg-87504/

forget the really silly stuff, stick between 20 to 30rps, your gun just dies quicker or wears out faster

above 25rps you will need to shortstroke - again I screwed that up first time round too

so like a lot of things go easy at first - most good builds and by that I mean the quality not speed

most good builds are 25% decent - not awesome high priced parts

and the rest is 75% attention to detail how well they fit together - often a bit of file/sandpaper etc....

youtube is good for some stuff but some videos are guys just taking apart a nicely built box and putting it back with parts known to work

some of youtube you wonder if their results are really that good or genuinely that fps/rof on that weight of bb or voltage ?

like many things - you can read & watch loads but in the end you gotta take off the stabilisers, roll ya sleeves up and just go for it

you will screw up but you will learn from your mistakes and nothing is that boned or you just get another box

if you can solder, then you can knock up your own 3034 mosfet, or buy a £10 FireStorm one

if you get into 20's rps that is very good steady build for many first few builds - seeing that a little work reaps good improvements

again for little money n time.

Kudos for having a go, double kudos of knowing to get it sorted and try again next time

is why I buy the cheaper stuff up to £150 - push it - break it - fix it or leave it until I have gained the experience to fix it

(I have a few spare guns and that is all I will say - most work fine coz I haven't killed them all yet)

no worries - we are all still learning and I have broken my fair share sir - hence I have a good box of spares (boned boxes)

 

[Shizbazki]

Sorry if i am late to the party but the one highlighted in bold was the problem i think:

I've purchased the following:

ASG Ultimate Cylinder

Madbull Alien Orange piston

ASG Ultimate Piston Head

ASG Ultimate Cylinder Head

SHS 13:1 gear set

SHS Air Nozzle

SHS Speed Motor

SHS Delay Chip

Assorted shims

I bought one of these once to replace the broken piston in my mates WE SCAR-L and experienced the exact same as you did, gun would fire fine on Semi but on auto a few shots it would lock up and blow the fuse, turns out the Madbull alien pistons are a smidge (i am talking .5mm) too long for most V2 gearboxes, caused me to lose 6 hours of my life trying to figure out why the gearbox kept locking up, replaced it with an SHS blue piston and it worked fine.

 

[Sitting Duck]

yup some boxes have more allowances at back on full compression

plus bearing spring guides & bearing pistons can add 5mm extra tension each from bearing

The joys of shortstroking can overcome this on hotter springs to bring down higher fps

but I ballsed that up first time also coz I went with conflicting guides saying from start or some said end of sector

I went with last teeth on piston - correct

and last teeth on sector as it sounded about right - WRONG it balls up the tappet timings

shortstroking is done from removing the same off back of piston (leaving at least 1 metal tooth of course)

and same amount of teeth of START or beginning of sector gear

Personally think a bit of MadBull stuff is not quite as good as people think

often there are very good and cheaper alternatives out there

(a lot of people over at Z1 seem to love them but when I tried one it kept jammimg on a 510mm one)

zci barrels I'm impressed with for value for money

still trying out numerous cheaper pistons - I avoid shs blue 3 steel teeth - too soft and plastic teeth shred easy on higher speed builds

thought they was perfect - really light and seem to run well but when pushed on the 3 steel pistons it just stripped quickly

ACM grey 3 & 7 steel tooth cheapo pistons seem to be holding quite well in 25 - 33 rps builds so far but still early days

not got around to using a really nice ASG/Ultimate piston but it is a bit heavy so maybe for a dmr build than high rof

yup learning from our mistakes is one of best ways to learn - providing they don't cost us too much grief in the long run

 

[smokebelch]

some more good advice there, thanks guys.

Will add, the tech at Patrolbase where I've taken the gun (hope its OK to name the place) didnt seem too impressed with the piston either, he suggested changing it for a mapleleaf piston, he said the madbull does have a history of failing/ jamming.

Again, very steep learning curve, with alot of lessons being learnt. Biggest one of all being to ask first in regards to what Im wanting to do, and how Im wanting to do it!

Brace yourselves for a mass of questions in the future when I look at upgrading my other gun!

I will add in my defence, Im a mechanical engineer by trade so it is in my nature to just go tear ar$ing into something without thinking first! lol

Will let you know how the upgraded gun turns out when I get it back in a couple of weeks

Thanks again fellas!

 

[smokebelch]

Sitting Duck, on 25 Jul 2015 - 11:41 PM, said:

is why I buy the cheaper stuff up to £150 - push it - break it - fix it or leave it

thats my thoughts, at the end of the day, all this is on a specna arms! Cheap gun, but I like the feel of it, and to be honest until I started on it it was working fine!! lol

Trouble is, counting the parts I've bought and fitted, the alternative parts the tech will fit, the cost of those parts, and the labour, this little upgrade is on course to cost twice what the gun itself cost!......another lesson learnt!!! lol

 

[Sitting Duck]

read also this:

http://www.airsoft-forums.co.uk/index.php/topic/17294-ians-guide-to-noobism-on-a-tight-budget/

a lot of "upgrades" may not be an absolute must do first time around.

often the piston o-ring is $hit and sometimes it can be real $hit - new o-ring is like 50p or a pack of 6 or 10 for £2

AoE is very rarely done - on the cheap neoprene rubber washers will suffice for most builds unless you are smashing high springs at high speeds

stock gears, piston and perhaps piston head often are ok - if the gears don't skreech and piston ain't stripped just a better o-ring will suffice

if anything an o-ring nozzle will help and if cylinder head is ok a few wraps of plumbers ptfe tape will improve seals

(or maybe get a double o-ring cylinder head and see how a new head n nozzle fit together)

any parts you replace from the few crap stock bits you might change like I said

make sure you FULLY compare them side by side and check how nicely they fit together & mesh/operate

sounds really easy - it kinda is but at first you tend to think all stuff will just drop in there and work just as good if not better

the sad fact is the TM compatible crap these parts are supposed to be comes in 3 forms:

1 - yup goes in there lovely and no adjustment or tweaking needed - not as common as you might think

2 - goes in but is a bit long or snags a bit and a bit if file/sanding required to a lot of work getting it to fit

(the more parts you replace very often you will have to check-double check everything every step of the way)

3 - bollox is that gonna go in there coz either the part is a duff pile of crap or the box you are trying to put it in

is one of them weird not so TM compatible boxes - so it ain't going in there no matter what ya do to it

the more you do the more you learn this first hand and you really need mainly 75% care and say 25% decent bits

to get most stuff sining better than stock - even some old crappy spare bits n bobs reassembled in ya gun will give good results

a couple of more times messing about in there and you will wonder what all the fuss was about

think you might have started to run before you could walk doing a complete strip & high speed rebuild with some bits

that maybe not quite working out all prefectly running together 101% without a bit of modding here n there.

no worries - if you getting all stressed take a step back, look up some info or post up here

we have all been there - don't be afraid to take pics - easy to figure out wtf that tiny thing goes

loads of tips and methods you will discover on your own and also learn from others

still learning - when I stop learning that is when stuff gets boring to me but for now keep the learning curve going upwards

 

[smokebelch]

think you might have started to run before you could walk doing a complete strip & high speed rebuild with some bits

with hindsight, yes 110% !!l lol

edit:

in fact in all honesty, I probably tired running a marathon before I could even crawl!