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G&G L85 - How to fix the trigger.


Stealthbomber

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A lot of people seem to have found there's a design fault with the G&G L85 trigger which means that, after a bit of use, it stops firing in semi-auto.

After going to the trouble of sorting out the problems with the blowback and the piston, only to find that the damned thing stopped firing in semi, my L85 has spent a quiet year in my wardrobe.

I finally got around to taking a look at it again last Friday (mostly due to the fact that it fell out and landed on my foot when I opened the wardrobe) with a view to fixing the trigger problem.

Well, I found a way to fix it, skirmished it on Saturday and have been giving it a lot of abuse today as well. I've put a couple of thousand shots through it over the weekend, mostly on semi, and I'm pretty sure the fix is reliable.

I'm just uploading pictures to photobucket and making a couple of paint sketches and I'll post the details up here in an hour or so.

 

So, that's it. The gun finally works. Properly. Bloody amazing! :D

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Okay, Photobucket has co-operated (finally) so here we go...

 

On a TM gun the cut-off lever hooks underneath the trigger block and pulls it upward to end the firing cycle when you shoot in semi.

The G&G L85 trigger block is a pretty poor design. The cut-off lever hooks into the side of the trigger block and, because of that, it's exerting an unequal force on the trigger block.

Instead of pushing the trigger block straight upwards, it twists as it lifts. That's the first problem.

 

The second problem is that the cut-off lever is actually a pretty poor design. It doesn't move very much at all. In fact, whoever decided to put the pivot point where it is wants shooting. Because the pivot point is 2/3rds of the way toward the trigger, when the sector gear cam pushes the cut-off lever roughly 2mm, it equates to less than 1mm travel at the opposite end. Boo! <_<

 

The 3rd problem (related to the first) is that, as a result of being twisted, the trigger block stretches out of shape very slightly.

 

As a result of the above problems, the cut-off lever no longer flips the trigger block up out of the way and the gun keeps on firing in semi-auto.

 

Something had to be done!

 

Trigger01.jpg

 

Yes, blame the cut-off lever. Curse it, swear at it. Spit on it. Unfortunately, you can't do anything with it to solve the problem so undo the tiny screw that fixes the wiring in place then turn the gearbox over and take a look at the trigger block.

 

Trigger02.jpg

 

Note that you need to undo the 2 allen screws that hold the motor in place, disconnect the motor terminals and then slide the motor off before carrying out the following modifications.

It's nothing to do with the motor but you need the motor disconnected to give you enough slack in the wiring to mess with the trigger block.

 

Trigger03.jpg

 

Remove the 2 allen screws that secure the trigger block cover plate. Note that G&G shim the cover plate to ensure it holds the trigger block firmly but not tightly. If there are shims under the plate keep them and put them back.

 

Trigger04.jpg

 

With the cover off you can see how the trigger bar pushes on the trigger block.

What we're going to do is file away at those two parts so that the trigger block will flip upwards with less force than before.

 

Trigger05.jpg

 

Once the motor wires are hanging loose and you've removed the screw from the other side of the gearbox you should be able to ease the trigger block straight out the right-hand side of the gearbox and then the white contact block can be removed and filed.

Take care not to lose the spring as you dismantle it.

 

Trigger06.jpg

 

The front edge of the trigger bar, where it presses against the trigger block, was also filed slightly round and finished with fine wet-and-dry so it was smooth.

This is done to assist with the job AND to help stop further wear as the metal catches on the plastic block.

 

Trigger07.jpg

 

Here you can see the finished modifications to the trigger bar and trigger block.

You only need to remove about 1mm from the face of the trigger block and just round off the edge of the trigger bar slightly.

 

Trigger08.jpg

 

High-tech MS Paint sketch showing what we need to do and how the 2 parts work against each other.

 

*** VERY IMPORTANT - IF YOU OVER-DO THE FILING THE BAR WON'T BE ABLE TO PUSH THE TRIGGER BLOCK FORWARD AND THE GUN WILL NO LONGER FIRE. ***

 

You have been warned! :waggle:

 

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Bonus....

 

mine has started to play up a little, occasionally not firing on Semi.

The lastest and more mind boggling little episode in the crazy life of my SA80 is that it is now double-tapping on semi, then missing a shot, then double-tapping again.

 

Time to dig out the spanners again me'thinks.

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Nice little tutorial Stealth'.

Does this also apply to the ARMY model?

Well, the trigger design is the same so I guess so.

 

I can't really stress enough that if you over-do this the trigger bar will slip underneath the trigger block rather than pushing it forward and the gun will, basically, be useless.

 

All you're aiming to do is reduce the joining surface slightly so that the pathetic amount of movement that the cut-off lever has is enough to knock the trigger block away from the trigger bar.

 

*EDIT*

Just occured to me...

Don't think I've ever heard anybody mention that the G&G L85 has 8mm bearings.

Does the AA gun have 6mm or 8mm bushes?

 

Also, am I the only one who thinks the L85 gearbox looks like a giant prawn? :unsure:

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...Just occured to me...

Don't think I've ever heard anybody mention that the G&G L85 has 8mm bearings.

Does the AA gun have 6mm or 8mm bushes?

Good question...hold on... *gets up from chair, opens box, takes <40secs (and just the one small screwdriver that comes with it) to remove lower gearbox* :D;)

6mm brass bushes.

 

Also, am I the only one who thinks the L85 gearbox looks like a giant prawn? :unsure:

Yes :P

Although looking at it I can see where you're coming from ;)

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Also interesting is that the trigger mechanism uses an active braking system by shorting out the motor contacts a split-second after the power is cut off.

Never really noticed this before. Was too busy swearing at the various mechanical parts.

 

Again, dunno if the AA L85 has the active braking feature as well.

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Shorting or reversing?

It just shorts the 2 motor contacts together. Doesn't reverse anything. If it did the battery would discharge (and the gun would melt) during the time when you aren't pulling the trigger. ;)

 

The motor instantly becomes a dynamo once the power to it is cut off. If you short the two terminals it's MUCH harder to make the motor turn and that's why it stops so suddenly.

 

I keep saying this but the G&G L85 has a LOT of terrific design features, including the active braking.

The split gearbox is good. The way the motor fits is good. The gearbox is a good design. You don't need to remove any of the bolted-on bits to open it up.

It's actually way ahead of the similar-looking TM M14 gearbox.

 

The way the inner barrel clips into the gun is good. The way the gun field-strips is good. The way the fire-selector and trigger aren't fixed to the gearbox is marvellous.

In fact, I reckon it's one of the best designed guns out there.

 

As usual, G&G managed to snatch defeat from the jaws of victory by failing to test the gun properly before releasing it.

I mean, seriously, is it possible that the gun could have gone through any kind of testing without somebody noticing that it eats pistons when you fire it in auto?

I really find it hard to believe that, with a bit more R&D, they wouldn't have chosen to sell the damned thing with a normal piston and spacer rather than the 18 (19?) tooth piston.

In fact, if it'd been me, I think I probably would have designed the gun with a thicker cylinder head so the piston spacer wasn't required but, meh! :rolleyes:

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...I keep saying this but the G&G L85 has a LOT of terrific design features, including the active braking.

The split gearbox is good. The way the motor fits is good. The gearbox is a good design. You don't need to remove any of the bolted-on bits to open it up.

It's actually way ahead of the similar-looking TM M14 gearbox.

 

The way the inner barrel clips into the gun is good. The way the gun field-strips is good. The way the fire-selector and trigger aren't fixed to the gearbox is marvellous.

In fact, I reckon it's one of the best designed guns out there....

Pretty much what I thought when I first stripped the AA...and that's why AA copied it down to the last detail I guess.

Is the reason for the longer piston simply to fit in with the gun's design (shape/size-wise) then?

 

 

 

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\

Is the reason for the longer piston simply to fit in with the gun's design (shape/size-wise) then?

I guess so.

 

If you look at an AR15, the gearbox sort of perches over the front of the magwell. In the L85 it has to be behind the magwell so they needed to find a way to make the nose of the gearbox reach a bit further forward.

 

I suppose, if things had been different and the first ever TM AEG had been an L85, they'd have solved it by inventing mags with the feed nozzle at the back rather than the front.

Then, when they'd made an M4, they'd have had to made it with a stubby little cylinder. :D

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Also interesting is that the trigger mechanism uses an active braking system by shorting out the motor contacts a split-second after the power is cut off.

The PSG-1 was the first model to introduce the braking effect. It's passive to be exact, because active braking means reversing the polarity and not just shorting the motor contacts. I believe the clone version has this as well. It must have, if the semi is working properly. Getting an AEG to pre-cock the piston is really really tricky if you don't have a braking circuit.

 

A very nice and clear tutorial. This applies to other AEGs as well: I've seen some M4/M16 series guns refuse to shoot semi, because the trigger was a bit too high so it wouldn't release the trigger block. So it's quite universal and not just nice to know for G&G L85 owners.

 

Your G&G has 8 mm bearings or am I seeing things? Because I could swear the ones I've seen had 8 mm solid bushings. Is that still the old A1 you bought when they were released?

 

-Sale

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  • 1 month later...

I finally got round to carrying out this mod, after being a little reluctant to do it due to the possibility of buggering it up completely. It works faultlessly now, sweet as a nut.

 

Sale I can confirm you're not going potty regards the bushings as mine has solid ones.

 

:)

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