Rebuild of a gen 8

Hey guys, just thought I’d start this thread for any one looking to mod there gen 8 or M4A1. So the story goes I bought a generic upgrade kit from eBay installed it watching YouTube videos lol the first time the build failed was because I hadn’t lock tight the plunger head to the piston and it came loose damaging a bunch of parts, the second time was because the gears were 13- 1s (far to fast for my build) and it stripped 2 sets of metal ladder gears. So I went an bought a shs piston to try and make the 13-1 gears work 🤦despite what I was told by the forum guys lol. And than this happened…! IMG_20200621_111648|375x500

I know I know serves me right lol. So now I am up for another set of gears, plunger and basically the lot. I guess i am posting this so maybe some others who are starting to mod blasters can learn from my mistakes haha. Sucks having to buy extra parts and basically spending double the money on a build that should cost you half of what youve spent :triumph:.


As someone gearing up to do their first internal upgrades I appreciate tf out of this post. Cheers dude🤙🏼


Lol cheers.

If I help one person out I am stoked and feel like the thread was worth it. Also I came across a nice little trick that most experienced techs would know but it took me some digging to find out. So the new Slimline bushings I’ve installed in my gear box were so tight that even trying to punch them into the allocated holes with a hammer wouldn’t work. So if you put the Bush’s into the freezer they will shrink a little allowing them to be installed easier or if it’s still tight ( like mine were) you can use the bolt, washer, nut method but they need to be M 3 size. Apply a washer on either side of the gearbox with the bushing in place and with a nut and bolt do it up untill you reach your required bush depth. Just make sure it’s going in streight before you really tighten it up. Worked awesome for me. Hope it helps.

very nice. i am in the process of building my gen8. and i had my piston head fall of too because i hadnt put loc-thread on :joy: oh well so you learn.

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Got a question for the brain trust if anyone is following this thread. Installing these 18-1 shs gears into my lucky gen 8 box has been an absolute nightmare I haven’t been able to get the gears to spin freely at all (no shims of course) even when I just have one gear in by itself. To say this gear box is tight wouldn’t be an understatement it’s nearly impossible to make them fit at all. I’ve been using a step drill bit to sink the bushings in deeper but I am running out of meat on the gear box. I think I could make it work maybe but the problem Iam having now is the bushing on the middle gear is now loose. And I have no idea how to secure it I’ve heard some people glue there bushes if they have to but can’t find any info about it. Has anyone experienced this problem before or have any info. Cheers.

First thing I’d check is if the bushes are in straight!! If they are in the piss a bit they will be tight. Yes I have glued bushes into a nylon housing before and it worked well. Be careful not to glue the selector plate in place… :man_facepalming:t2:

Hey mate, yeh they are streight, just curious what sort of glue did you use?

Not superglue… if they go in crooked they’re staying that way :joy:

Five minute epoxy works well and gives you a bit of time to make sure things are right before it sets off.


If I need to switch the bush out later will heat or something dissolve the poxy or is it a more permanent solution?

The five minute doesn’t set as rock hard as the high strength, so a bit easier if you need them out again. I can usually lightly scrape it out with a scalpel blade if I want it out.

There’re plenty of experienced builders on here who use other adhesives, I’m sure they’ll help you out. :blush::+1:

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