Gg Umg Intermittent Trigger Sticking/Stiff Issue

[WhiteRyder]

Hello All,

Really hoping with your experience someone can ID the issue i am having on my UMG. It started while in use and i think it started from when my battery (lipo 7.4v (25/50c)) when flat while i was in full auto in an intense firefight (so didn't notice it running low). The trigger jammed as far back as possible, putting in a fully charged battery didn't change this and changing fire modes wasn't possible and it was stuck in semi... i forced the trigger back with quiet a bit of force (a repeat of this can be seen in first video below) and then i could change fire modes and use the gun again and it shot normally expect the problem still exists where it sometimes jams back while in use (like every 200 shots I guess) and it also now has a problem of the trigger needing a very hard pull from the start position of its travel (an example can be seen in the second video link) quiet often (like every 50 shots).

Warning: I may have dropped some swear words in the videos (watch on silent if that would offend?)

Video link showing the trigger locked to the back and me forcing it forward:

https://drive.google.com/file/d/1pQd_jzZQ7jl2SGYl0Umiy7k015mXroVb/view?usp=sharing

Video link showing the trigger being very hard to pull then the gun shooting normal(?):

https://drive.google.com/file/d/1pHpvwWByzju3J0Il6dhoCv9pR44ikTTt/view?usp=sharing

some extra notes that may be relevant:

• seems to struggle more in semi mode but think it does fail in full too. i think the trigger lock to the back has only happened in semi but the stiff pull from the beginning of its travel does happen in full for sure.
  
• its normal that a half pull of the trigger only cycles half the shot (normal to this gun anyway it has always been the case (not the best trigger action on a UMG)
  
• changing form decent to budget BB's had no impact on issue
  
• im not confident enough to open the v3 gearbox up
  

Any help would be apricated and im happy to answer any questions or even make more videos to get to the bottom of this, thanks in advance.

 

[Sneaky]

The only thing I could think of is that something is in the way of the trigger arm, past the pivot point.  Could be a wire has moved, but something is getting in the way of that trigger pull, as it should be a smooth action.

To be honest with you, do you know someone who has the knowledge of opening a v3 gearbox.

 

[WhiteRyder]

Thanks for the reply, I dont know anyone with gearbox experience as I'm quite new to the game. I could give it a go myself and follow YouTube, I will have the tools but not sure how much damage I could do with no experience?!

 

[WhiteRyder]

View attachment 62919noticed (after taking gearbox further apart, this pic was to help me put everything back in right place) that there is a missing bushing on the gearing behind the trigger as seen in middle of pic. I assume this is the cause of the problem and now have replacement 6mm bushing on order and some shims just incase. Will give gears a tiny bit of grease while in there too. 

 

[Sitting Duck]

my initial reaction...

Don't worry too much about nozzle position - it is just a bit slight overspin

(and I mean slight, if it was seriously pre-cocking, the nozzle would have retracted & returned)

Too many people worry about nozzle position thinking something is wrong - it isn't if all operates OK

By the looks of things you have more pressing issues to concern yourself with

6mm bushings, how old is this gun ???

Which might indicate a bit of wear (so much the bushing worn away completely - sarcasm)

think you might want a pack of shims too - coz can't see any on that sector/missing bushing-gear

take pics (loads), but try to change as little as possible - just get her working again on your first attempt

do a couple of dry runs closing up box without spring, so you get the hang of fiddly trigger & Cut Off Lever

(all trying to jump around as you close it all up)

Get the hang of how it closes up - springless, will help you when you finally close the box fully

Best of luck

 

[WhiteRyder]

Hi,

UMG comes stock with 6mm (oiless) bushings I found out, even the new ones still on sale, my gun is about 6 years old and has fired 10k~ in just the last 6 months alone I quickly calculate from memory.

Glad the nozzle position isn't an issue thanks for the info.  

I did get the gearbox completely open (and have plenty of pictures if you wanted to see them now) and honestly when putting it together again is when I noticed the missing bushing as the other bushings were out of alinement with the case (attached to the gearing still rather than the case). Seems doable from what I have seen and now read on these gearboxes but the shimming process sounds time consuming and with a bearing missing its probably needed as may have had one there. I plan to replace all 6 bearing FYI.

Thanks for the advice, 

 

[WhiteRyder]

Problem fixed. 6 bushings replaced, the remaining 5 were tatty and the shimming was pretty much nonexistent so my probably rookie shimming job should be better than nothing. Greased it up too abit. Gun shoots and sounds nice now.

I have spotted a crack forming in the piston so I wonder if it's best to replace now or wait for it to fail if that's still potentially a long way off?

View attachment 63119

View attachment 63120

View attachment 63121

 

[WhiteRyder]

update for anyone with a similar issue that finds this thread... from replacing the busings and greasing the gearbox and putting back together again the gun went from 285fps on 0.25g bb's to 334fps on the same bb's!!!!!!!!!!!!!!!! My gun was too hot to play with so I had to purchase a spring to down grade the fps so I could play yesterday, lucky they had an on site shop and I had the tools in my car so took it apart on the floor of my car!

 

[Lozart]

Definitely replace that piston head!