Urgent: Gearbox advice

[Garf3r]

Today i rigged up my l85 with a external PEQ box 9.6 3600mah battery, (i usually use 9.6 1600mah ones inside)

anyways after firing it (over 3 mags of 120rd's) i heard the infamous screach! i opened up my l85 and got to the gearbox to find the gear had unaligned itself, so i though shims, so i shimmed the gear, put it all back together, fired it again, it did it again, only in less time, so i opened it up again to find that the other gear had unaligned, so i shimmed that one too, put it back together, it now works but im wondering, is this going to happen again?

I have a plastic blowback gearbox, now this is a star, not a ares, so im wondering, should i get the metal gearbox and avoid this again? Or have i fixed it and wont need to

I need to kind know by firday on what to do.

[madwelshman]

Re: Urgent: Gearbox advice

well, changing a 9.6v for a 9.6v shouldnt have made that much difference, true, the discharge voltage will have increased slightly, but ROF wont have been affected too much if any, your gain is in how long the battery will last.

As for the issues you've now incurred, they are down to poor shimming, should have shimmed all the gears, not just the one, but hey, as long as nowts broken, now everythings shimmed, you shouldnt have a prob anymore. Keep an eye on that plastic gearbox though, wear and flex will/could be an issue in the long run

Personally, i'd take out that blowback bollocks, its only asking your gearbox to work harder, adding more strain

[Garf3r]

Re: Urgent: Gearbox advice

the blow back is only a plate witha catch and as the piston goes back anyways it takes it with it, and theres a return spring to bring it back, the plate is ultra light.

as for the shims, i realise the mistake i made when first upgrading the gearbox 2 yeras ago

it seems to be in working order now, im going to run 12 mags through it 2moz and see how it performs

just hoping i dont need to fork out £60 on a new metal gearbox, so would the shims that are no in place stop the gears from unaligning?

[madwelshman]

Re: Urgent: Gearbox advice

they should do, the only problem you might find is theres too much shimming, fingers crossed there wont be any issues now, its not uncommon for guns to be incorrectly shimmed, my CAm15A4 was from new, but it stil worked for 3 years, till I had it serviced, then was told how badly shimmed it was! lol

Hopefully you've sussed it mate, the gbox should hold up, thats what its designed to do!

[Garf3r]

Re: Urgent: Gearbox advice

ill wing it for now, ill run as many mags threw as a can, a cant believe that changing to a bigger bat made it go crazy, or maybe it was gona go anyways, have no idea, but a tell you this 9.6 3600 seems 20x faster than a 9.6v 1600mah

[Caveira]

Re: Urgent: Gearbox advice

I'm open to correction from someone who knows electronics better than me, but my understanding is that the higher discharge rate gives a higher level of torque (for lack of a technical description) to the set up. Like using a longer handle on a socket wrench, you don't need to move it any faster to have more effect.

Poor shimming is always an issue, but with the plastic gearbox, the added strain put on it by the battery may be making it flex beyond it's normal limits.

Also, if the blowback mechanism attaches to only one side of the 'box (which it sounds like it does), then this will cause additional strain, as it will create a tendency for the casing to twist.

[Garf3r]

Re: Urgent: Gearbox advice

it doesnt attach to the gearbox in any way, its a plate on the side yes, but theres a solt on the top of the gearbox that this just sits in and as the piston goes back it pushes this along, the blowback has never been the issue, its my shimming i reckon

[madwelshman]

Re: Urgent: Gearbox advice

yep, you will allways see the difference in say, even a 9.6v 1600 cheapsoft, came with the gun battery, compared to a decent quality 9.6v 1600 decent quality one, when you up the physical size, so the amount it kicks out, like drinking a coke through a straw, or just picking up the glass, and taking a good swig! its the same size, but lets more out. up the size on the battery and the discharge rate normally increases drastically, giving you more oommpf

[Garf3r]

Re: Urgent: Gearbox advice

ah but it will last longer though, hope it will as that was the point, got my eye on a 5000mah one

[madwelshman]

Re: Urgent: Gearbox advice

you might find the discharge rates going to cap off, dependant on sizes.

a mini battery, is capped at a discharge rate of 25amps (25,000mA)

a large type battery, well, I havent seen one with more than 30amps (30,000mA)

They might be out there, but the 5000mAH wont be faster as a discharge rate, than one at 3600, it will just last longer, think of mAH as the storage capacity, (like a bigger glass of coke! lol) the bigger the number, the longer it will last on the field!

(stats from a 10.8v 1400mAH but only 2/3a cells)

10.8V 1400mAh 2/3A mini battery pack Airsoft Vapextech

Weight: 220g
Capacity: 1400mAh Measured at 280mA (0.2C) discharge.
Capacity at 15A discharge: Typically >1350mAh
Max Discharge Current: 25,000mA (25 Amps!)
Max Charge Current: 1400mA
Size:136mm x 45mm x18mm

Although you will see an increase in rof, the discharge rate will drop, its a weird one, the benifit would only be slightly in favour. Some have even found a decrease in rof, increasing thier battery voltage size, i.e. from 8.4v large type, to a 9.6v mini, as they couldnt fit a large 9.6 in there, only to find due to the drop in discharge capacity, they loose rof!

[Garf3r]

Re: Urgent: Gearbox advice

ah right so see when it comes to charging this bad boy up, what current should i be puttin her through?



i have that charger and it only goes up to 4amp, n it says thats for 2600-6000mah, but see when i do a rapid charge, it does it for a wee bit then cuts off to the beep but it aint fully charged :S

[madwelshman]

Re: Urgent: Gearbox advice

yeh, NEVER fast charge any battery at 4amps! or you will well and truely screw your battery!

I have given up workking out the equation what I do is, if its an over nighter, long charge, I whack it on 0.5a and let it run, it then clicks onto trickle charge anyways. fast charge, 2a max (used to do 3a, but I got told off! was told that was too much! lol)

[Garf3r]

Re: Urgent: Gearbox advice

so soz for been a total pain, if its say the 3600 im charging, on say 2amps, a rapid charge it, it then cuts off to trickle, so how long do i leave it at trickle? 5 hours or sumit?

[jagillham]

Re: Urgent: Gearbox advice

Charging calculator:

http://www.zeroin.co.uk/showthread.php?t=17927

[Gaffa]

Re: Urgent: Gearbox advice

Actually fast charging is completely normal - look at the many thousands of airsofters who use a Pro Peak. That charges at 3.5A, so 4A won't do much more.