First AEG Repair / Upgrade Completed Successfully

[Crunchmeister]

I've successfully completed my first repair and upgrade. Some of you probably read my thread a while back asking for help identifying a mystery part that had fallen out of my mechbox (http://www.airsoftcanada.com/showthread.php?t=49527). The thread then expanded asking a few more questions about a few problems that I had. I made a last post in that thread the other day saying that I had managed to reassemble everything, but was having another issue.

For a brief history on the gun for those who haven't (or don't want to) read the other thread. I blew out the spur gear on my TM M4A1 in early December. I figured if I have the gun apart to repair it, I might as well also do some internal modifications. I ordered a Modify torque-up modular gear set and a Prometheus MS110SP spring. Earlier attempts to install the parts had failed (read the other thread for details if interested). So knowing that I would soon be getting a C8 metal body for the gun, I shelved the project until a couple of days ago when I went through the whole process again.

At first, I though I was successful. I mounted the mechbox into the lower receiver, installed all the pins, grip, and motor, and managed to successfully fire the gun. Upon reassembly of the rest of the gun, the gun would no longer fire. I was rather disappointed, having been proud of myself for having baslically built a "new gun" from the ground up with a new body, etc and had it working up till that point. But it was late and I was tired so I put it aside until I had more time to properly troubleshoot it.

Tonight, I finally had time to try again. From my observations, it didn't seem like the motor was being powered at all, so I figured the problem might be electrical. After checking the intergrity of the fuse, I opened the grip and removed the motor, then reconnected the wires to the motor and pulled the trigger. There was no power to the motor, so either the motor had died, or it was an internal electrical problem. Touching the battery leads directly to the motor terminals made it run, so I narrowed it down to an electrical problem.

So once again disassembled the entire gun and mechbox. I discovered that one wires on the trigger mechanism had broken loose. I quickly soldered it, and reassembled the mechbox. Upon mounting it into the lower receiver with the grip and motor, it was once again firing. I assembled the rest of the gun successfully, and it's now completely functional. I now have my metal bodied TM M4-based C8A2 - at least it's first steps. I still need some cosmetic mods to complete the look, but this is definitely a good start.

The performance has increased pretty significantly. Since it was stock , I'm assuming it fired at roughly 280 fps like other stock TM guns. It might have been a bit faster because I run a 9.6V battery instead of an 8.4, but I can't imagine it was too much higher than that. Now it's ROF is lower due to the torque-up gears. It's still fast, but now it's slower than my CA M15 rifle, whereas before the upgrade its ROF was faster than the M15's. But the power increase is pretty dramatic. For its initial test fire, I loaded up my 2 of my 130 rnd midcaps and fired at my almost new Crosman 'gel' target (only had about 200 rounds fired at it from my pistols) at about 20 feet. I not only hit the target accurately, I went right through it! So I had to find out how powerful it had become.

Damage done to the target after firing one 130 magazine at it

I performed the Coke can test at 1-2 inches as per the "Poor Man's Chrono" guide on Redwolf's site, and I managed to punch right through both sides of the can. I was unable to penetrate the bottom or edges of another coke can. According to their chart, that's 350 to 370fps. I'm very pleased with the results, as this was the approximate velocity I was going for.

Yeah, I'm quite proud of myself on my first successful teardown and upgrade of my gun and to have such fantastic results in the end. It took several attempts to get it right, but it's working now, and it's been a fantastic learning experience for me. This is probably laughable to a lot of you guys who've done this 20 739 times, but to have done it all by myself (with a bit of advice from some of you guys along the way) feels like quite an acheivement for me. And now I feel quite confident that I can repeat this process on any Armalite and no longer feel intimidated by it. I'm definitely not overconfident to the point of thinking that I'll never run into any issues or problems with future work, but now that I've disassembled and reassembled my C8 so many times, I know the process well enough that I'm no longer afraid of breaking my gun. I know all the parts from the mechbox to the externals and how they go together. And I now know most of them by name too, so that's also a good start.

I feel so confident, in fact, that my M15 is next to get upgraded. Within the next couple of days (after some research and price-shopping), I'll be ordering a new spring (another Prometheus MS110SP that should get me in the 380-390 FPS range), piston and piston head (these last 2 in order to replace the chronically problematic CA parts). And after that, both guns will be receiving tightbore barrels to increase their (already good) accuracy. The C8 will also be receiving a heavy outer barrel for cosmetic purposes.

And a note on the Modify modular gearset. I don't know how much time people normally spend shimming gears when doing a fresh install, but these things are a great time saver. The gears are all pre-shimmed and attached together in this pre-assembled unit. All you do is pop in the new steel bushings and install the gear assembly. Getting the anti-reversal latch and tappet plate in is a bit trickier because of the "outer shims" on which the gears are mounted, but it's quite easy after you've done it a couple of times. Their action is very smooth, so I'm assuming that means they are indeed correctly shimmed. I'm a noob and I don't really know what to look for in a good shim job, but if it's completely fluid motion without any signs of grinding or friction, then these gears do exactly that. I wouldn't hesitate to install a set in my M15 should I encounter grear problems with it.

Modify Modular gear set

So just for pimpage, here's a couple of pics of the final product - at least in its current stage of the mod process.

[Forever_kaos]

Great to see and hear that you made it through and you learned alot. I'm still waiting on 'cracking' my gun apart for upgrades after the 26th and with Ancorps help. Glad to hear your triumph though!

[Crunchmeister]

Yeah. I feel great about this. Considering 2 of my 3 current AEGs are Armalites, with another one (HK416) coming soon, I'm pretty confident I'll be able to maintain, repair and upgrade my Armalites without having to ship them off to a gun doc whenever I have a problem or want them upgraded. I'm sure I'll hit other stumbling blocks and problems, but at least now I know how things are supposed to work, so I'll be going in with some experience under my belt.

Since I fired an AEG for the first time last fall, I've been fascinated with them and how they worked. Really, the whole gun and mechbox are pretty simple devices. But they're also ingenious devices with how well such a simple deisgn works so well.

By installing this metal body, I've essentially built this gun from the ground up, except for a few minor outer parts and the wiring and selector switch assembly in the mechbox. It's been a great learning experience and I'm glad I did it. I was very intimidated the first couple of times I opened up the mechbox, but once I did it a couple of times, I found at least most of it is fairly straightforward once you know how it all works. But still, there will always be problems that need to be solved. I know I had my share! lol

But I'm glad I did have these problems. It caused me to do a lot of troubleshooting, disassembly, reassembly, fitting, repairing, etc. And in the process, I was forced to closely examine all the internal workings of the mechbox and how the entire AEG works. I developed a fairly good understanding of what happens inside the gun to make it fire, and what happens during the firing cycle. It's been an invaluable experience. And IMO, there's no better way than to learn hands-on from experience. Having someone who knew what they were doing with me to walk me through the process would have been much easier, and I more than likely would not have had all the problems I had, but I definitely wouldn't have learned everything I did doing it myself. I didn't break anything during the the build, so it's all good.

That being said, I'm hardly declaring myself an expert or calling myself a gun doc, but at least now that I've done it, I feel good about doing it again (and again, and again...). lol

[ThunderCactus]

V2 is my favorite mechbox to work with, it may not be the best but it's easy to put back together lol

[diamond_SEA]

Ya i just got my v3 mechbox up and running again, and its not an easy reassembly.

[Wilson]

I love that C8!

[AngelusNex]

I taught myself too..... on a v3, surprisingly it wasn't so hard for me, now I work on mine and my friend's guns

[CDN_Stalker]

V3 annoys me a lot more than the V2 does as far as assembly goes. Currently am working on a CA G36K and the mechbox (largely the trigger and shims on the bevel gear) annoy me the most right now. And I'm swapping springs to try to get it under 400fps (had a 120 spring in it, not sure the make but it's pale green anodized, leads me to believe a Prometheus, but was shooting upwards of 430fps) for the owner to sell it. Tried my old PDI 150% (350fps in stock MP5) and it sits around 395-405fps, and the new Madbull 110 springs I have in stock, 415-425fps. So you can see I'm getting WELL acquainted again with the V3 mechbox and all it's rugged annoying glory!

Glad to hear Mission Successful for you Crunch, happy to hear some of my info helped you out.

[seabass]

Im gonna be balls deep in a v3 next week for the first time, It should be fun, shimming is the only thing im worried about

[Omi-san]

I prefer to work on my V2 as well.

My V3 trigger assembly (CA G36k) pops out all the time. So does the spring and I can't keep it in place using the hole at the back of the mechbox like on the V2. With one hand holding the trigger and one holding the spring down, I couldn't close it.

I ended up using the sticky blue paste meant to hang posters. Just enough to keep the trigger assembly in place without hindering with its movements. Then I could easily close the mechbox.

[Crunchmeister]

I have a question about motor seating. Can it affect velocity? I don't see how it could, but this is what I observed tonight and want to run it by you guys. I'm a noob and out to learn as much as possible so that one day, I don't have to bug you guys with this stuff.

Tonight I took out my newly upgraded C8 for a little target practice in my house. I bought a new target to replace the one I destroyed with this gun on the weekend, and set it up at the end of a long hallway in my house. From my firing position, I was about 30 feet from the target. That extra distance was enough so I wasn't blasting right through the target this time . The BBs were hitting very hard, but didn't go through.

I shot off a couple of 68 rnd mags in mixed auto and semi-auto and noticed the motor's sound seemed louder and more high pitched than before. I assumed (and correctly so) that it was because my motor was too low. So I started to raise and lower it until it ran as quiet as possible.

I loaded up a 130 round mag, and started firing again. While I can't comfirm this, the sound of the BBs impacting the target seemed harder then before I adjusted the motor. The way I understand it, The motor drives the gears, and the sector gear drives the piston and tappet plate. When the gear releases the piston, the spring releasing is what creates the compression and in turn, determines the velocity of the BB. The motor shouldn't have anything to do with it the release cycle. Yet, the impact sounds appeared to be louder than before the motor adjustment.

Now, the impacts may also have just sounded louder because I no longer had the motor whining right by my ear. Without the extra high pitch whining noise from the motor near my ear I might have been able to hear the impact sounds more clearly.

So, motor seating affect velocity, or was I mistaken thinking it shot harder?

As a side note, I also realized that those Modify gears have made my gearbox a lot more silent than before. The new spring has definitely made the sound of the shots a lot louder (in a good way), but the gearbox itself is very quiet in comparison. When stock, this gun's internals used to be a lot louder than my M15. Now with the motor correctly seated and the new gears, you can hardly hear the gears and motor over the sound of the shots. I'm quite impressed with these gears and I may just get a set of high speed Modify gears for my JG 416 when I receive it.

[m102404]

Awesome work and great write up! Nice to see someone put the time and effort into sharing their experiences with the rest of the forum in such a thorough way.

I'm not sure about the motor seating depth affecting velocity...even if the extra pressure of "over-seating" the motor resulted in slowing down the gears, when the sector gear finishes pulling the piston back everything but the spring and piston are removed from the "power" of the mechbox...so the piston should go forward as fast as it ever did. I could be complete wrong on this (I'm often wrong...but I learn fast!). You're probably experiencing the "Proud Papa" syndrome...where the elation of getting your rifle working in that sweet spot enhances all your senses...LOL!

There's definitely a sweet spot when the gear noise is the "deadest"/quietest when seating a motor.

If you have to work on the mechbox again...you can cheat and just hook the grip/motor up to the mechbox without having to install the mechbox in the lower receiver...saves time and reduces the number of nicks you might make knocking out and reinstalling the flora pin. You can still test the full function of the mechbox (safe, semi, auto) by manually moving/holding the selector plate.

Last note...are you using the stock TM mechbox shell? I've not had it happen...but there's plenty of reports here that it does not do well in the cold...

Great stuff!! Now the madness of building your next M4 from scratch begins...

[Crunchmeister]

Yeah, that's how I understand the gun to work too, and I don't see how the motor or gear speed could affect the BB velocity, since the gears are completely free from the piston when this happens. I'm leaning towards thinking it just sounded that way because I could hear the impact sound better without the motor noise. I just had to ask to make sure. I'm fairly confident that I totally understand the workings of the gearbox now that I've had to troubleshoot it so much on my own.

Yeah, I was actually thinking about that while at work today - attaching the grip and motor right to the gearbox to test. Glad to hear that actually works! Had I thought of that on the weekend when I was having all these issues, it would have saved me a lot of time installing and reinstalling the gearbox in the lower receiver to test it out! Man, that was so time consuming.

And yes, I'm using the stock TM shell. The only internal upgrades are the gears, bushings and spring. And of course, the metal hopup unit for the metal C8 body.

Not sure about building a gun though. I mean, I've essentially done that with this gun, since I had it torn down almost completely to do the work and upgrades on it. I have too many Armalites as it is. I'll have my RS T56 in about 2 weeks, then I have to start looking into an MP5 and a machine pistol to round out the collection. Possilby an M249 to convert to a C9 down the road. Yeah. If I ever get another Armalite, it will more than likely be a Systema PTW.

And I will rave about them some more. In terms of operation, these Modify gears are SO worth the $80. I love the sound of this gun now. You can barely hear the gears at all. I just fired off another 68 round mag here in my basement, and once again went through my new target. Guess I'll have to use the BB trap when using this gun and save the target for my pistols.