Something in my mechbox snapped off. What is it?

[Dozer_01]

Hey folks,

So my gun died at the recent wasaga game. It appears one of the motor wires wasnt touching the actual mechbox on the way to the motor. It's kind of odd, but i fixed that part of it. I took a look at Arnies step guide to dissasembly, and did so in the correct way. I opened up the shell and the trigger unit decided to bulge out. I carefully put it back in place, then about 10 seconds later the trigger flies out. wtf eh? So having took it apart, i decided to take a look at what was actually IN these systema M120 complete mechboxes. The internals were lubed half assed. I removed the whole wiring/ switch assembly and came across a broken off post seen in the below picture.



I just put that post back up for the pic...it cleanly snapped off...
Is this required? Could that have caused the trigger to bulge out?

Any help is appreciated.

Thanks guys.

[mcguyver]

That post is what stops the top contact slide from being pulled out of the switch by spring tension from the little spring which sits directly below the tappet. That post is required.

[CDN_Stalker]

Holds the trigger and contact block in position. Both will pull back under spring tension and you'll find the trigger block angles up and rubs on the tappet plate. Had two mechboxes do the same thing. I just drilled a small hole, tapped it for #4-40 screw threads, then Loc-Tite'd in a short set screw to replace the post. Works perfect every time.

[Dozer_01]

Oh ok.

Thanks guys. Im glad i didnt totally scrap my shell.

cheers!

[JohnnyDo]

Originally Posted by CDN_Stalker

Holds the trigger and contact block in position. Both will pull back under spring tension and you'll find the trigger block angles up and rubs on the tappet plate. Had two mechboxes do the same thing. I just drilled a small hole, tapped it for #4-40 screw threads, then Loc-Tite'd in a short set screw to replace the post. Works perfect every time.

I second this suggestion. I ahd to do this to a mechbox a couple of weeks ago. I used drilled, taped and inserted a stainless steel bolt with loctite. After I knew the loctite was cured I used my dremel to grind the height down and to grind off the head of the bolt on the outside of the mechbox. worked excellent and really was not all that hard to do.

#4-40 is also what I used as anythign larger would interfear with other components.

[ILLusion]

This is a super common problem with Progear/G&P reinforced mechboxes.

It occurs if you do a lot of semi-auto fire.

It's made a lot thinner than standard Marui gearboxes in order to accomodate full-toothed sector gears that require half-tooth pistons such as Systema Infinity and Ultra Torque up gear sets as well as Prometheus Max Torque gears.

Best way to avoid it is through prevention. If I don't intend on using one of the above-mentioned gear sets, I surround that entire post with steel epoxy and once it's hardened, I grind it down to shape.

[Guardian]

Originally Posted by ILLusion

This is a super common problem with Progear/G&P reinforced mechboxes... ...I surround that entire post with steel epoxy and once it's hardened, I grind it down to shape.

Interesting you have to reinforce the reinforced mechbox. It's always something isn't it.

[CDN_Stalker]

They gotta make their money somehow, right?