When I wanted to upgrade my M1A1, I found no internet guide, takedown FAQ, nothing. I hope to remedy this with this guide. I am by no means an expert on internals, my photos may or may not suck, and I might have even forgot some pictures that may help, but hey, this is literaly all that's out there. Any comment, suggestions, or critisisms are welcome. In fact, if I've done anything wrong, please let me know.



Do takedown the M1A1 you will need, at a minimum.

---Assorted Screw drivers, Phillips and flathead.
---A torqe driver set
---a hex key set

You also might want some glue, I'll show you where.



This is the screw that holds the upper and reveiver together. A large flat screwdriver does the trick. Notice that the screws that go through the stock from side to side don't need to be touched, ever.



You can also remove the other screw at this point, but it is not neccesary. Now push the small tab at the lower back of the receiver, it should push in easily. Now push HARD on the upper receiver, towards the front end of the gun. Make sure you have a grip on the lower reveicer as well, the upper will slide off the lower with pressure.



The lower and upper receiver taken apart. Notice that the hop up is attached to the upper receiver and barrel. I did not take apart the hop-up, and I won't unless I have to. Sorry. Also, note, that if you went ahead and took the whole stock off already, the nut that holds the shorter screw in. This is where the glue comes in. Find out where is goes(there is a slot made for it, not too hard to find) and glue that thing back in. It won't affect the operation of the gun. Set the upper reveicer somewhere it won't get in the way, you won't be needing it for the rest of this.



Next, remove the pistol grip. Another job for a large flathead screwdriver.



Then the pistol grip comes off with a little pressure.



Next comes the motor cage. There are two, brass looking screws on the right side of the gun. Medium Phillips.



This post has been edited by hsimoorb: Oct 18 2006, 08:36 PM

Simply pull off the wires from the motor connectors, and remove the housing.



This is the tricky part. Unfortunately, it's also the worst picture I have. Basicaly, there are two, tiny, inaccesable little hex nuts that you have to loosen. Loosen, not remove(I made the mistake once). There is one hex nut for both the selector lever and the saftey, you need a tiny little hex wrench, and a lot of paitence. I cannot stress enough that you only need to loosen these by about one and a half turns, not remove them. After that's done, the levers will slide right off.



When you remove the levers, watch for these little buggers coming off. They might fall out of the lever, they might not. Just keep track of them.



A cruddy picture of where that nub thingy is supposed to go.



At the end of each of the selector guides, is a small, phillips head screw. Remove them.



After the screws are gone, those guides simply pop out.



If you have not already removed the stock entirely, do so, and disconnect this small connector.



With a little force, the greabox should now come out of the lower receiver.



There are three, black, plastic bits that are not firmly attached to the gearbox. This photo is for reference when you put everything back together. The peice you put in the forward and rear positions does make a difference. One is for the saftey, one if for the selector. For now, remove all of them and keep them in a safe place.



This is, again, a reference photo.



Start the mechbox dissasembly with this screw...



...and this one. They are both small torqx screws, neither have washers,



The switch assembly can then be removed.



Whatever this thing is called, I used brute force to push it off, towards the rear of the mechbox. If there is a better way and force and force alon please let me know.



For whatever reason, this peice here can pivot on this one screw. Once the gearbox is put together ad screwed tight it is immobile, so I don't know what it's use is. Either way, it's a standard phillips screw, remove it and the mystery peice it holds on.

***I don't have pictures of this next part, forgot to take them. Not that it needs pictures though. There are two torqx screws, on on the top front of the mechbox, one towards the rear. They both have washers, so don't loose them. Also the rear one, for whatever reason, has a brass sheath around the screw, and is wedged in between two tabs on the machbox, just make sure you don't loose it and put it back when you assemble the box.

Also, after you do this, there is nothing holding the shell halfves together anymore. You're going to want to release as much pressure on the gearbox as possible, by releasing the anti-reversal latch. It's quite easy to get to, through the opening for the motor. it's towards the front of the mechbox, simply push it so it disengages form the bevel gear, in case the spring has excess tension, this will releive it.

Next, et a small screwdriver, insert it into the rear of the mechbox, where there is a small hole. Push down on the screwdriver, this will keep the spring from flying everywhere when you open this thing up. When that is done, pry apart the two halfes and...



Another referece pic. I will not do a close up of every mechbox part, only the ones where you might have trouble.



Piston, and piston head, unscrewed. I show this because of that small metallic peice you see. It goes on the inside of the cylinder and it is what the piston head screws into. Also, when I first disasembled this, the stock marui spring was actualy latched onto this peice, so you had to unscrew the stock piston head to get it off. Hard, becasue you have to cut away a part of the piston head to get to the screw. Also, this metal peice has a latch that goes into the cylinder, and keeps it from rotating. ***Being as inexperienced as I am with internals, I realy don't know if this is common, or something that marui did to add a little wieght and give the thompson the pleasant pop-pop-pop report that it has.



If you know about V6 gearboxes, you know that one of the sets of bushings is odd sized. This shows the proper orientation in the gearbox, in case you got confused. You can also put the sector and spur gear in the box, and see if the gears mesh properly(that would be the right way to do it)

Thank you SO much for this tutorial, couldn't find anything out there either.

One word of advice, rename your post from GREARBOX to GEARBOX. Got an extra R in there. It might help people who search for the word gearbox, I only found this post by chance.

Any tips of modding the bolt so it attaches to the piston or spring and moves with the firing mechanism? I've heard it's been done before, just don't know how to go about it.

Lol, I just noticed that typo. Too bad I can't edit the post now, new time I'm definately going to spend some more time correcting spelling in the future. As it is I went over this thing twice correcting things and as you can see, there are still some bloopers in there.

As for the bolt-mechanism thing. There are guarder kits for the AK that do the same thing, but they require you to literaly cut a long hole in your gearbox shell. If you're willing to do that, I don't see why it's not possible. All you'd have to do is fashion something that would connect the bolt and the piston. It would DEFINATELY reduce the lifespan of the gun to fruit-fly levels though.

This post has been edited by hsimoorb: Jan 1 2007, 01:42 PM

Do you have a link to one of those kits?

It explains how to do the conversion too.

Well I managed to do it. Awesome mod. Check out the video in my post below! Was done without a kit, all by hand and I somehow managed to pull it off.

Hasn't seemed to affect the performance of the gun at all.

I might re-inforce the parts so that I can get a longer lifespan out of them. A whole gearbox upgrade will also be done soon, to make sure of the stability.

Here is the link to the video in case you missed it.

http://www.youtube.com/watch?v=0x2UaqiInqk

It's just... sweet :D

Like I said though. Dunno how long the plastic piston will last. Stainless steel here I come!

hey I just installed metal bushings, spring guide, sp120 and a piston head. I got it all togather and went to shoot it but it made a little noise and stoped. I think the gears locked up. So I opened it and found my tappet plate had snapped were the cam pulls it back on the gears. If remeber what kind of shimming u had that would good.

Here is a link to a new tappet plate: http://www.trinityairsoft.com/ps-484-35-ta...s-by-angel.aspx

V6, right?

Indeed.



Huh? Would you mind re-typing that?

Is youre air nossel/tappet plate spring really stiff? It seems it takes a lot of strength to push it in when its in the gear box.

Yes, I've noticed that the tappet spring is a lot stiffer than in any other gearbox I've worked on. As long as it has full range of movement, you'll be fine.

Ok, thanks.

It just seems hard to believe that the tappet plate can take that much strain at the cam contact point.

Do you know where I can find a Thompson OUTER Barrel (not the actual barrel but the outer barrel with iron sights)? My friend got a Thompson and he needs an outer barrel to replace the one he has now( don’t ask how/why its a long and boring story). hes willing to buy a used one if he has too.

thanks for the help,
totman

This post has been edited by totman: Mar 11 2007, 05:52 PM

http://www.uncompany.com/pageproductdetails.asp?prodid=6560

Thanks a Ton

totman

THANK YOU THANK YOU THANK YOU... I was looking for this for so long

I just couldnt figure out how to remove those selector swithces... if I knew how to earlier, I could have fixed my barrel too which had snapped off and now held together by super glue ( works very well)
* be careful when carrying this thompson on your back the barrel will began to woble

but I wanted to upgrade it with a Deep Fire M120. which should give it around 390 fps. I want to know how much the mechbox can take without having to get new bushings and gears.

The bushings in the pictures were metal. Did the come that way?

Those are aftermarket guarder bushings in the pic. If you're upgrading to 390fps I'd definately suggest a set of those. The gears will be fine for a while, but you might want to look into a new spring guide w/bearings, and a new piston head w/bearings.

Alright thanks but I found out that those only give it around 350, so do I still need anything else to upgrade?
I really don't want to tamper around with anything else besides the spring because ive heard about kids getting there guns to shoot lower then 200 fps and jamming up the gears

do you know anywhere where the sell those hurricane upgrades?

For 350 you should be ifne with just the bushings and the spring. Just so you know though, you'll have to tamper with the piston head to get it off the spring. You can either clamp it with some pliers and twist it off, or cut into the piston head to get to the screw head.

I would definately not suggest hurricane uprade parts. They're pretty much uniformly lower than TM quality, part for part. Go for Guarder or systema/area 1000 bushings, and a PDI spring.

alright thanks, well I know I have to remove the piston head but what I meant by tampering is with the gears while knowing about all the things that can go wrong if I don't shim them correctly or get the wrong timing

alright thank you very much, your guide was a big help
for right now im just gonna upgrade the spring and look into the other parts when I have more money willing to spend

pivoting piece

quote:
For whatever reason, this peice here can pivot on this one screw. Once the gearbox is put together ad screwed tight it is immobile, so I don't know what it's use is. Either way, it's a standard phillips screw, remove it and the mystery peice it holds on.


answer:
It is for mounting the motor horizontaly backwards for use in the P90.

sorry for the necroposting but I see some important things I learned that haven't been addressed
Good review, also, as I didn't see this I don't know if you knew this, but the hex are a 1.5 on the metric scale I do believe.
Also, with the Cybergun/Cyma Thompson, the spring can be rather stiff, so I recomment sliding a thing screw drive down the back, into the spring guide, and keeping a hand on the cylinder. If you don't you run the risk of ejecting one or both of these parts, which I have done, and that can damage them, or damage the room you are working in.
Also, when reinstalling the gearbox, you must pay attention to where the wires go. If they are not secure they will get pinched and damaged, and/or your gearbox will be stuck or wont go in. If you gearbox wont go back in, stop, check to see if the wires are binding and DON'T assume that it is just a tight fit. if you do, all you will hear the next time you pull the trigger will be "click, click, arrrrrrr" because you just did what I did, and broke the wires. This goes for all gearboxes, don't try and force them.

I'm just going to chime in here and say that the Cybergun/Cyma Thompson is a very very close clone of the TM. The only differences I've seen are that the plastic on the nibs for the safety and select fire switches and the safety lever piece are white plastic instead of black plastic...

And, yeah, watch the wiring... that's always a watchword in AEG's, but more so on this particular one.