G36C Trigger Problem

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MisterG

AF-UK patch owner
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So, after a few successful upgrades I got cocky and thought I'd take apart the gearbox as FPS was going from 320 to 345 and thought maybe there was an air leak.  Put PFTE tape on the cylylnder head to get a better seal.

All seemed ok after a lot of faffing getting the trigger spring right.

However after a few shots, the trigger shuttle/trolley jams.

I've taken it apart 3 times and still get the same problem after a few shots.

I've google and checked Youtube, but can't seem to find a solution.

Anyone have any ideas?

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Anti reversal latch, it’s always the ARL! Or the way you have left the gears.Have you any photos of the box open?

 
I feel like such a tit.

Turned it over to take another picture and it is the safety catch blocking it.  Which is weird, as it would fire a couple shots, then stick.

If I push the safey catch all the way it fires fine, full auto.

Cheers

G

 
Actually it's the selector to be more precise.  Must be missalinged inside.

At least I'll be an expert in V3 gearboxes when it's sorted.

But I'll leave it for the morning, too knackerd to take it down for a 5th time.

G

 
Managed to get it working more or less, then a tooth broke off the piston.  Not having much luck with AEGs atm, maybe I'll take another look at that Tippman for sale?

Looks like I'll be running the Evo outdoors on the weekend, unless I can get a good cylinder in time.

Cheers

G

These were the pics in case anyone spots anything obviously wrong.

The last pic shows when the switch arm which presses the microswitch slips and jams.  Anyone know the right name for that part?

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The cut off lever on G36's can sometimes ride high on the trigger dolly and cause the trigger to slip.

Do you find if you pull the trigger slowly you get a normal single shot, but if you pull it fast you get a partial cycle or just a blip.

One of the fixes is just to file down the cut off lever nub that sits under the dolly just a fraction so it doesn't touch the dolly until the cam on the sector gear throws it up. Go too much with the filing and you will need a new cut off lever. So be warned, and go slow if you go this route.

The problem isn't actually the dolly or the cut off in this instance, it's wear on the upper part of the tracks that the dolly rides in. Once the upper track wears to a certain point the cut off lever is in always on mode. A new contact group will also fix it if you don't want to mess with the cut off and is a more recommended fix.

You also need to check the back of the dolly. I can see the trigger has a nice sharp edge to push the dolly, but the dolly might have a rolled/worn step at the point where the trigger pushes.

The trigger riding that upper track due to cut off pressure is where trigger resistance comes from on the G36. So if you like the tighter trigger like new get a new contact group. If you want a light trigger file the cut off.

 
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I ran out of time to do any more on that gun, am having more severe gear box issues, which I will try to work on this weekend.

Motor sounds like it is revving loose/not making proper contact with the gears and needed 2 trigger pulls for single fire.

It might be just need some more grease since putting in the new piston/piston head, or didn't put it back together right.

I'll post some more pics on Saturday as the internals have changed.

 
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I've put a picture up of where you would file in a regular trigger system. However looking at those images I think the problem is the dolly.

I've highlighted the parts that get pushed by the trigger, you need to inspect those edges. They should have a sharp defined edge that the trigger can push against. I think yours have worn down to a curved edge and that is why it's failing to push the dolly. You might be able to re-cut a square edge onto those with a warding file.

The trigger spring can also be positioned better, Get the loop on the dolly at the bottom not the top of the spring, It might help keep the back edge down.

Other than that I can't see an awful lot wrong there. And certainly not something glaring that would cause the trigger to ride up like yours is.

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Looks like you didn't put the AR latch back in correctly this time.

Gearbox is rotating correctly then hitting a hard stop. The 2 hard stops in the video are in 2 different positions.

The gearbox is then rotating backwards.

That would suggest the AR latch is catching the spur gear on forwards drive, And not arresting the gearbox when the trigger is released. You got it the wrong side of the bevel gear I'm afraid.  It wants to be the motor side of the bevel gear, like you have it in this picture.

You have an inspection hole on that shell,  Inspect your box and I bet the AR latch is pointing towards the airseal nozzle.

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The AR latch is in correctly then.

It's getting to the stage where I would send it out, as it seems there is a problem that isn't visible on the pictures.

If It were my Gearbox I would strip and rebuild it fully. But I know the V3 box pretty well and would be able to see and feel any problems. Via pictures that isn't going to happen. So your only option is to go find someone who knows V3 boxes and have them take a look. If you lived closer I would take a look for you. Chances are there will be guy at the mall that @Duff can recommend, he seems to be a little social beaver in this regard.


 

 
Ok, thanks for all your help.

I'll try changing the pinion gear, and if that doesn't do the trick, I'll probably look for a tech.

This is now my project gun, so may also decide to do a full strip down myself, just for the experience.

 
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It could be the pinion is slipping, but I would still expect the AR latch to hold the piston if that was the case. That full reset of the piston is throwing me as it shouldn't be happening.

Assuming 18:1 gears.

1 turn if the sector = 18 on the pinion. 10 teeth on the pinion. So 180 teeth on the pinion for a cycle.

30ish teeth on a bevel gear. So 6 turns per sector revolution. (24 AR latch notches)

Your seeing about 50% of the piston travel back, so 1/4 turn on the sector. That should be 6/4 = 1.5 bevel gear turns.

1.5 bevel gear turns should give 5-6 opportunities for the AR latch to engage assuming it's got 4 locks per turn on the bevel gear.



It should work out that you have 15 degrees on the sector gear for each AR notch. Something somewhere is wrong. I noticed you put a new piston in (blue v/s the JG) it might be bad engagement on the piston, and the AR latch is working, but the piston itself is giving you the problem. Or the piston head isn't well fixed and it's allowing the front edge of the piston body to ride up off the sector.

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I took the spring out and I can manually get the piston to do a full cycle by turning the gear that engages with the pinion fom the motor with my finger.

So I think that probably eliminates some of the issues above as a cause.

I'll see how I get on with the new pinion.

I believe the gears are stock, so 18:1 should be right, I'll double check when I open it up again.

Cheers

G

 
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You seem to have a handle on it but yes I do highly recommend Luke from the Mall. If you get stuck go and bend his ear.

 
As this is now my spare gun, I have time to get it sorted.

I've watched loads of vids on v3 gearboxes on Youtube, challenge is this is a  non-standard v3, with a microswitch.

I've taken it apart so many times now, I can put it back together without looking ?

Getting it working is the next step :rolleyes:

Cheers

G

 
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