Will I get PME?

[Katana]

So just finished a new build as old one was even more stressful and died after use so new specs are:

Lonex Gearbox - 8mm Bearings

SHS 16:1 gears

Lonex bearing spring guide

SHS lightened 14 tooth piston with AOE corrected

Lonex POM piston head

Lonex cylinder

Lonex cylinder head

Lonex tappet plate

Lonex nozzle

Gate Titan

ASG 30k Motor

Guarder M90 Spring

I know the whole gearbox isn't necessary to post but what the hell. Anyway this is what I am worried about...

Because of the weak spring I am worried that I am snapping all kinds of sh*t up inside the gearbox. RPS is definitely around or above 30 and maybe 31 or 32

I could Short stroke the gearset and I do have my old lonex spring which was an m120 with a few coils cut off and I ran -3 teeth on the sector but I literally pretty much only have 11.1v lipo's and really enjoy the insane TR + If I can help it, I would rather not do the whole SS thing because it is annoying but if it is necessary I can still do it. 

I mean could also also grab a pdi 6.08 barrel instead which should lower the fps so that I can put that lonex spring in which is probably more like an m115 or m110 now and not need to short stroke. Again, I'd rather not as I have a prommy in there right now at 6.03 and it gives out some good results. Anyone know?

Thanks guys

 

[Dechande]

Just short stroke, it's not difficult (15 minutes with a dremel?), you'll get better trigger response and it'll greatly reduce the chance of premature engagement, especially with the faster gears.

If you've spent all that money and time already, just buy an M100/110 for a few quid.

 

[Katana]

Just short stroke, it's not difficult (15 minutes with a dremel?), you'll get better trigger response and it'll greatly reduce the chance of premature engagement, especially with the faster gears.

If you've spent all that money and time already, just buy an M100/110 for a few quid.

True but I don't want to do it if I don't have to. I want to work out if I simply have to first before going through with it. I'm thinking that the lightened piston changes things slightly.

 

[Sitting Duck]

Think you are close to it myself (and so do you or you wouldn't be asking)

in fact I'm amazed she isn't over-spinning or double firing but the Titan's AB is kicking in to lessen the over spin

Running the gun on full auto is where you will wreck it

semi with AB you will be ok as piston is stopped asap before you risk hitting the fan

OK - how is the piston head fitted to piston ???

did you use the bearings at piston head - if so lose them

buy some of these:

http://www.ebay.co.uk/itm/Black-Nylon-Plastic-SPACERS-Standoff-Washer-M3-M4-M5-M6-M8-M10-or-M13-12-PACK-/331684716193?var=&hash=item4d39f31ea1:m:m83Kn_qgDKqTDOiMEmnM_Tw

15mm diameter x 10mm thick & maybe 5mm thickness

On your piston you probably have this:

get rid of these bearing/race stuff for starters....

Those 2 x races/washers & bearing weigh about 3.5gms and they compress the spring by about 4.5 - 5mm 

Now take a 10mm spacer if you wish to SS

or a 5mm if you don't but I advise that you do SS with a 10mm spacer

you may need to widen the M5 hole in those spacers to fit the collar mount through - no biggy

now add a race if you like to ensure the nylon spacer doesn't get chewed up over time from spring

(not an absolute must if the end of spring isn't sharp or have a 'ooky bit or burr on it)

now you have a thickness that is now 11mm AND weighs 2.5gms !!!

So you have saved 1gram - wow (Every little helps as Tesco says)

Plus 6mm extra spring compression !!!!

EDIT - in case you haven't figured, you will need a 5mm longer M3 bolt though

(old gearbox case bolt lying around perhaps ??? Or Fleabay M3 aprox 15mm - 18mm)

This now means you can remove the first two teeth on the sector gear going from 16 down to 14 teeth

The spring will still be compressed the exact same but the stroke is 6mm shorter and piston is 1gm less too

This theory bit on paper is the exact same BUT there is a slight tiny thing to take into account though

The stroke is shorter which if you have a ported cylinder will still be the exact same - volume wise that is

HOWEVER - think of the piston & its release like a standing 1/4mile at Santa Pod say....

Your official 1/4 mile is now say 10 yards shorter so your actual top max speed crossing the line may be slightly less

Not much at all tbh but all the same need to point out a possible tiny drop say 5fps

yes you lost 2 x 15fps from removing 2 teeth on sector but the extra 6mm spring compression claws that back

So you should get the same figure but the slightly shorter release or run-up

means the final speed or max acceleration is a whisker down so to speak - reckon about 5fps

Now on the other hand you could SS more/less than 2 teeth but depends on your barrel

if you got a full 455mm then no you can't SS at all really coz you need a full stroke

at say 380 or less - well a 363mm you can SS 2 teeth or perhaps 3 teeth no problem

Back to the build in question.......

16:1 gears are actually about 17.25:1 - aprox 8% not expected 12% increase over std 18:1 gears (18.65)

They offer little extra resistance in gearing to slow a released drive chain/motor so overspin or piston appearing in window

(13:1 & 12:1 gears are much more strenuous or a steeper hill start in helping to slow drive chain on non-AB mosfets)

Anyway you got AB in Titan so now biggy I guess but if possible tweak the AB to only moderate braking if possible

The 16:1 gears would likely put out a 19-20 rps on 7.4v

you are running (with quite a risk imho) 11.1v so this would get to say 30rps maybe a couple more coz of bearings

It is risky if you unleash hell on full auto as I explained

I certainly would strongly consider SS 2 or 3 teeth with a higher spring like m115

and/or spacers to compress the spring if needed on original or if fps is a smidge low after SS

Anything past 25rps on full stroke is starting to risk it a little....

the gun should be overspinning or getting near firing twice if AB is disabled/not fitted

a titchy gun like MP5k will likely need a m115 to produce anything near 340fps

due to short barrel so a MP5k could cycle a little faster than a full size AK47 perhaps

But in general around 25rps is about where you get overspinning bordering double firing

Reason you probably are not getting this is Titan's AB but I'm damn sure you would otherwise

We are not going to completely eliminate the overspinning just by taking off a couple of teeth

you would probably need to look at say 4 teeth & m120 - but then you gotta be careful if taking more teeth off

say 2+2 each side but that can mess with tappet release timing - so you trim tappet fin but add longer delay clip

or you take say 3+1 but still cycling at speeds you may start to effect the timing slightly.....

think it should be ok but tbh....

All we are concerned about is PE or PME smashing up stuff

So yeah just consider perhaps SS 2 teeth off the sector's first 2 teeth

DO NOT TAKE OFF THE LAST 2 TEETH !!!!

First 2 teeth that engage the piston first at the large initial pick up tooth

You can then put in the m115 or space up the existing spring by 6mm - the 2 x 3mm pitch teeth you remove

Phew- no doubt I have gone way overboard once again

 

[Sitting Duck]

True but I don't want to do it if I don't have to. I want to work out if I simply have to first before going through with it. I'm thinking that the lightened piston changes things slightly.

If you are crapping yourself - don't

The 16:1 & 18:1 sector gears are the same - or should be

So you could take an old sector - 16:1 or ye olde 18:1 sector and grind the f*ck out of it

as long as it spaces/shims up ok with the rest of the shs set you will be fine to use an 18:1 SS sector gear

no need to muller the rack a couple of teeth as long as last tooth on sector is not a jumbo fatty tooth you are fine

If you are worried - grab a 18:1 ye olde sector - see if it spins ok in box

then dremel the hell out of it

it is when you bollox a 12 or 13:1 sector you end up kicking yourself coz you are a bit screwed

but 18:1 & 16:1 sectors are same

(should be)

Finally - if you ignore this risk of PME you may wreck your piston - maybe bevel if it smashes up

Then you will get not only PME but also be a bit upset like a tart with PMS

yes you could dial in some bells n whistles settings to lower rof I guess

(I don't have a fancy mosfet - damn thing costs more than many of my cheapo guns)

or run on 7.4v and be well safe but you would lose that snap you just fell in love with

It is up to you & your call in the end

 

[Katana]

Thanks for the help Duck,

I'm going to look up some tutorials on the safest way to not f*ck my sh*t up short stroking. I kinda knew that I would have to do this beforehand anyway but didn't really want to believe it. I don't have any 18:1 gears by SHS lying around so I guess I just can't f*ck up haha.

I'll shave 3 teeth off of the sector gear on the pickup side and then if my fps is too low, I'll then do the piston head compression mod as you said. I believe the piston head does have the bearings installed but I am about to go back inside of it now to SS so then I'll know for sure. 

On the up side, the new asg motor I just picked up is a freaking beast. 16tpa just like the shs high torque but man this thing is built like a tank. I needed a new one because the SHS HT I had just died on me which was kinda weird but the amount of crap that kept building up on it was ridiculous and the Titan actually stopped working and gave me the error fault for damage to the sector gear which there was and a faulty motor but at least it is working now.

 

[Sitting Duck]

I'll shave 3 teeth off of the sector gear on the pickup side and then if my fps is too low, I'll then do the piston head compression mod as you said. I believe the piston head does have the bearings installed but I am about to go back inside of it now to SS so then I'll know for sure. 

I'd just take 2 off tbh - you can take another tooth off easily

can't put it back on later if you went OTT

you got a chopped m120 Vs a m90 Guarder which is really a m100

So the m120 is at least a m115 or possible m110 if it was run in or faded like springs do

each tooth equates to ROUGHLY 15fps or m005 if you like

so 2 x teeth would knock off 30fps or m10 of that m120 that is likely a m110 I feel

if the spring is irregular and fitted correctly - tight coils at spring guide

then fitting ar$e about face - tight coils to the piston head will increase fps by about 10fps I have found

should be fitted correctly to assist in easier spring retraction

but tbh 10fps on 16:1 gears on beefy motor won't give it a hernia

(just a thought if you are trying to regain/lose a few fps after all this "fun")

I'd go for just two teeth first on the old chopped m120/115/110 spring and see how you go

than go too nutz - even with best maths n testing in a APS UAR it is still a bit of a guess work

(a less wild guess but all guns vary & all that a little)

Oh and that copper dust is the brushes & commutator wearing out on the SHS

I don't think SHS's love 11.1v too much, there was geeky link about brush composition

The correct brushes are firmer but their make up was different that they didn't wear

or wear the commutator as much as softer brushes or something way over my head

something to do with different wear patterns on the commutator indicating this n that

(way way over my thick skull head - I run on 7.4v with say 13:1's and so far ok)

All motors suffer wear on the commutator over time but think SHS don't love 11.1v a lot

Hopefully the ASG might last longer considering the cost & build spec

or was it this one....

I don't know/care

rebuild the SHS with a lame stock std motor winding (say 22tpa+)

and you should get a very torquey motor to pull DMR or 12:1 stuff no problem

 

[Katana]

I cut 2 teeth as you said but on my last build i had around 340 with the 3 teeth cut on 13:1 gears and the same spring i am going to use so if i am going to use the same setup but with 16:1 gears, would that equate to the same fps or does using 16:1 gears change the fps when it comes to short stroking some way?

 

[Sitting Duck]

I cut 2 teeth as you said but on my last build i had around 340 with the 3 teeth cut on 13:1 gears and the same spring i am going to use so if i am going to use the same setup but with 16:1 gears, would that equate to the same fps or does using 16:1 gears change the fps when it comes to short stroking some way?

Nope - gears and motor speed or rate of fire do not alter the fps

well I guess you could argue going nutz full auto generate friction heat wear in o-ring causing seals to lessen blah x 3

But f*ck me that is splitting hairs on a flea or something.....

Nope - gear ratios n stuff don't effect the fps - that is down to stroke/compression/volume & crap

you should get the same fps on semi regardless of gearing

stroke length - yes but ratio nope

Each gun is slightly slightly different....

you can try the wider barrel if fps is a smidge high and not happy with shooting

or take off another tooth if she is shooting say 355 once hop is all dialed in correctly

then another tooth should get her down to 340fps

but you would be kicking yourself if you find at a max of 325fps and hop needs a tweak etc...

or that would drop to 310 or less from 325 if you chose the 6.08

I'd rather go down a smidge at a time than lop it off and regret it

A pity you not got a spare sector - I got a couple of SHS's 16:1 sectors I'll never use

(got one here left over coz used the 16:1 spur & bevel (not sector - dohhh) in the FH HC05 DSG)

So if you balls it up lmk & I'll send you a couple 16:1 sectors if you need them

I won't use them I don't think

So with that in mind if you wanna say WTF & chance it then cut a 3rd tooth off

(just going by your own findings of how that spring worked out)

Not sure if the set was a gen 3 (likely) but should be 101% compatible

 

[Sitting Duck]

I cut 2 teeth as you said but on my last build i had around 340 with the 3 teeth cut on 13:1 gears and the same spring i am going to use so if i am going to use the same setup but with 16:1 gears, would that equate to the same fps or does using 16:1 gears change the fps when it comes to short stroking some way?

Yeah WTF - cut off a 3rd tooth if you are sure the spring was pushing 340fps in same/similar gun

If it is well down then I'll send you another sector and you just cut 2 teeth off to put back say 15 fps

it is just sitting here doing nowt anyway....

see lazy bastid, hasn't moved for hours

 

[Katana]

It's altogether and actually sounds healthier than it did with the m90 which is weird. The shimming hasn't changed at all or the motor height but it just sounds healthier. Strange....

Thanks for the help man. I won't be able to test the fps until the end of this month which is kind of a bummer but I'm sure it is about right. If it isn't then I'll probably buy an m115 or m120 to up it again as I think it will only benefit from the added spring strength. I'll chuck the m90 in some low stress, random slow build which I could whip up pretty soon and use that as a backup. 

Thanks again man. 

 

[Sitting Duck]

Well if you need owt gis a shout

16:1 sector or a spacer or two if you want

 

[Katana]

Seems like my fps has taken a nose dive meaning that there is a tappet plate timing issue but I did shave off from the pickup side. Is it possible that my sector gear shimming is too high and the tappet plate is rubbing against it? I don't have a sector delay chip on my sector gear so maybe I need to add one?

 

[Sitting Duck]

Seems like my fps has taken a nose dive meaning that there is a tappet plate timing issue but I did shave off from the pickup side. Is it possible that my sector gear shimming is too high and the tappet plate is rubbing against it? I don't have a sector delay chip on my sector gear so maybe I need to add one?

you sure the hop/box went back ok if it was working ok before ?

if the screw or stock tube M5 bolt goes in real tight the front of box can tip up and scrape for crap seal

you sure the hop is pushed back correctly to seal against box ???

if it was working ok before

Normally spur is shimmed low with say a 0.15mm shim & a thin one on top if required

(SHS gears are quite chunky which leaves little room to shim if bushings/bearings are a bit chunky too)

Sector is normally spaced half & half - with bearings I'm guessing say 0.20 on both sides of sector

Delay clip - might need one @ 30rps

http://www.ak2m4.co.uk/internal-parts/gears/zci-gear-delayer

nice clip and fit either way too

think you might need to investigate for hop/box alignment first

then if no joy then delve deeper but unless your sector is shimmed high tappet should reset fine on release

you can check clearance by placing tappet in other half of box, then the sector gear to check for rubbing etc...

PITA these bloody guns

 

[Sacarathe]

Someone mind decoding PME? Google wouldn't tell me what the E stands for.

 

[Katana]

I dont think it is alignment as I haven't changed any of the pats like the hop up but could of put it back together with something a bit off so after checking that, it doesn't seem to be alignment. 

I fitted a sector delay chip and even on a 7.4v, the gun shoots about 30 feet and then plummets with hop on or off irregardless. 

Can you put a sector delay chip on the wrong way round because I have never fitted one and took the SHS one off of my 13:1 gears to fit the 16:1's but it doesn't seem to have helped at all?

My spur is shimmed very low with I think about 0.2mm on the bottom. I backed off the rear screw a bit and tried because it was screwed down quite a bit but it doesn't like it. Deffo looks like it is firing like it's about 190ish or something which obviously means there is some real sh*tty air seal somewhere. Just trying to find the little bastard. I put a lil extra grease on my sector just to see if I got this issue before I last put it back together so if it is all smudged as f*ck, maybe that'll show it. I'm using the abbey lt2 gun grease and I saw that it was kind of sticky in low amounts and I put some of that on the sides of the tappet plate so could that be it? Just a random thought, I doubt it but I suppose it is worth mentioning.

 

[Katana]

Someone mind decoding PME? Google wouldn't tell me what the E stands for.

Pre-mature engagement. When your piston can't reset in time for the sector to pick it up again so it scrapes against the piston rack early and wears both the sector and the piston down. The faster your gun shoots, the worse PME gets. Unless you up the power of the spring, lighten the piston etc.

 

[Sitting Duck]

It's altogether and actually sounds healthier than it did with the m90 which is weird. The shimming hasn't changed at all or the motor height but it just sounds healthier. Strange....

This bit is throwing up some questions though....

Are you SURE the spring you put in is what you think it is ???

And as you said you can't chrono etc....

I'd be tempted to plop the m90 Guarder in there just to check stuff

no way should the fps drop that much unless perhaps the spring isn't what you think it is

even if you fit the spring previously in an AK 455mm full cylinder to get 340fps

You would of lost say 30fps on SS 2 teeth so is your barrel say 200mm  or something to drop over 100fps

(that is assuming the 340fps spring was being used a longer barrel like 455mm)

I'm thinking something is out of whack or the springs are not what you think/expect them to be

or you had a 455mm build and now a 200mm barrel to lose expected fps that much

or you got some springs mixed up

The bit where it sounds healthier - could be a lighter spring than before (as well as a slightly less stroke but not DSG stroke)

So the spring power is maybe much less and will sound healthier if it is really low

just wondering what happens if you swap springs - can't get no worse (would of thought)

 

[Katana]

The spring is definitely correct, I put my Lonex spring back in it's packaging the second I took it out when it was taken apart the first time.

 I think the sounding healthier came from the motor height as the G&P grip is a tight fit for the motor so it gets wedged and I pushed it down beforehand and then put the motor plate on which may have put it in slightly too far which would explain why I coulnd't work out why it sounded fine a second ago and then now all of a sudden doesn't. I placed the motor in the next time I put the lonex spring in and let the motor plate push it down which made it seat correctly.

I have no idea the brand of the delayer that is inside but I thought it was an SHS which apparently it's not as this one is metal and not shaped like the universal ones but shaped like it should go a certain way round. I've switched the delayer around so it's facing the opposite way to how I installed it and am going to see if that helps. The gun was shooting wildly as well with obvious inaccuracy problems and more of a loss of compression than just an fps drop as it was extremely inconsistent.

I have my hop up/ everything outside of the gearbox setup like this:

Lonex Gearbox

Lonex Hop Up Unit - 4 o-rings added to push against the gearbox and seal (worked on my last setup with the 13:1's perfectly and nothing there has changed

Prommy hard flat nub

G&G green bucking - Flat hopped

363mm Prommy Barrel 6.03

Edit: With the sector clip switched around, I won't be able to see how she shoots til the morning

 

[Sitting Duck]

is this the delayer...

or this one...

The first one can't be reversed coz it is chamfered a bit

The metal one goes one way only

The purpose is to hold the tappet back for a longer duration but not too long in higher speed guns

It is to help it feed better that is all, if the tappet is held back for too long the tappet timing can seal late at nozzle/hop

you can trim the fin to release it earlier to compensate and/or cut coils on tappet spring to get tappet returning faster

The laughable thing in all of this is DSG's don't/can't have delayer's but they feed ok - though need good mags

The delayer is not a must for general modest builds say @ 20rps

but @ 30rps it would help or assist on some weaker/picky mags that was all

I'd consider forget delayer atm as it may only add to the problem at this stage

check tappet spring is quite strong and the area inside box doesn't have any crap in front of it

Keep the box simple - remove delayer if your mags are good

also if you haven't glued the nozzle onto tappet yet (you should of)

then sand down the tappet plate front to jam nozzle a smidge more forward perhaps

Next thing is to very closely examine the sector and tappet plate fin at rest

Right by the axle shaft the fin can on some builds especially a mix n match build

The fin can get restricted by the sector's outer axle or copper sleeve the shim sits on

yes I know it is a v3 gearbox but the lower cut out area of fin is required to allow the fin to fully return

this may also happen if when you shave tappet plate front - might wish to go forward more

but might be restricted on the center of fin hitting the copper sleeve

NOW I'M NOT SAYING START TEARING UP YOUR LOVELY LONEX TAPPET PLATE FIN !!!!

I'M SAYING CHECK IT ISN'T STOPPING THE FIN GOING FULLY FORWARD

The odd thing is if/why she was ok but after SS the fps dropped so much or leak appeared

which was why I was suggestion was spring actually what it said on tin

I've got various bits mixed up before but ok we will go with spring was pushing a chopped m120/115