Systema/G&P Mecha-Box advice? *EDIT* Project complete!

[zener]

Hey guys,

I'm in the midst of building an M4, so far I've put together:

-G&P Zombie Killer Metal Bodypt# gp542b
-G&P Body Furniture kitpt# gp790b
-G&P CQB/R RIS w/Barrel pt# gp249
-G&P Extented Battery ButtStock (Crane style)
-G&P 9.6v 2200mah Battery
-TM EG1000 motor
-Magpul Grip
-TM 363mm inner barrel
-King Arms 200mm Silencer

I'm planning on using the drop-in style Systema mechbox for the simplicity of not having to get one built and putting parts together. I've decided that the M120 level mech-box is the most practical for the style of play, feild FPS limits, etc.

I'm a loyal Redwolf customer and I've made most of my purchases from them. As a bonus, they offer free shipping on all systema gear boxes. So, no brainer, buy mechbox from them.

Unfortunately they only ever seem to have the front wired versions of this box and not the rear wired versions. I was planning on buying the rear wired one but I'm at the point where I'm just going to get the front wired box.

So is there any difference (aside from wiring) between the two boxes? Advantages/Disadvantages?
Is there much of a hassle to route the wires to the back?
Should I wait another 3 months(or whenever) for the rear wired boxes to get back into stock?

This is my first attempt at buidling a gun and I consider myself a little-wet-behind-the-ears in the feild of "M4 AEG assembly/disassembly". Is dropping in a mechbox, wiring, and lining up gearbox to motor myself going over my head?
Redwolf posted a warning about:

The alignment of the motor on your gun to the first bevel gear must be done correctly in order to avoid stripping the gears on first test.

How do I go about lining everything up? Is there an internet guide/tech article for lining up the motor to the bevel gear?

Sorry for all the questions... I appreciate your patience. Look forward to any advice.

Thanks,
Joel

[Styrak]

You can have the motor misaligned and test it, and it won't have to much bad effect, just fire 1 shot on semi and listen. If it needs adjusting, adjust it and fire once again.

It doesn't do that much harm to the gears.

Also, you could get a magnum or turbo set for about 300 shipped, which includes a motor, from www.airsoftglobal.com or maybe other sites, I didn't look any farther than that.

[ILLusion]

Get the front wired version (for M4/RIS) and rewire it to the back. All it takes is one wire approximately 1 foot long to replace the positive wire that runs from the front battery compartment to the trigger switch. Swap that and run it to the back.

Next, take the black (negative) wire that runs from the front power to the grip... and just run the wire from the front out the back. Nothing needs to be cut or replaced - it's just a regrouping.


This is easier, cheaper, and more reliable than getting a rear-wired version. If you get a rear-wired version, you'll either have to:
a) De-solder and resolder new wiring from all contact points leading out the back of the gun = extra money spent on wiring
OR
b) Cut off the battery plug coming out the back and solder on longer leads = insecure splice which could lead to crimping from the added bulk - this could potentially lead to a short circuit and burning battery right besides your face. Not fun.


Besides the wiring, the difference between the front-wired version and rear-wired *may* be the cylinder size. It's weird, I've seen the rear wired version with both a full (M16) cylinder as well as a ported (SR16) one.

If you're not familiar with splicing, desoldering and soldering (to get the Dean's plug on to the new gearbox), this project may not be something to tackle yourself. There are destructive modifications that need to be performed on to your receiver to get wiring out the back.
Although the G&P instructions say to hack a hole to let the wiring go through, there is a WAY better alternative. As long as you maintain 16AWG wiring (or smaller), you can just run them through the buffer tube. A groove will need to be cut in to the edge of your receiver to allow the wiring to snake from your gearbox through the lower receiver in to the buffer tube. Doing it this way will allow you to completely separate the gearbox from the lower receiver. Why G&P suggests the other method is completely beyond me...

As for motor alignment - read any Tokyo Marui manual. It tells you how to adjust motor height. There are also many guides and posts on this particular topic across the internet as well as on ASC. The *best* way to check motor height is to open up the gearbox, remove the spring, spring guide and piston assembly and then close up the gearbox. Screw it up at some critical points to keep it together, then attach the pistol grip, motor, motor plate and grip plate and run it that way. Removing the spring takes all tension off the gears and reduces any misaligned stress against the pinion & bevel gear.

[zener]

Thanks guys! I appreciate the quick replies.

I'm fairly familiar with soldering as I have to deal with it on occation with my line of work. I think I sometimes let things appear more difficult than they are, I guess I needed a little confidence booster. I'll take your advice ILLusion and go with the front wired gear box.

I'll update this thread as things progress and I'll likely have more questions.

[bruce]

You might want to get another spring besides the one in the mechbox if you plan to get a tightbore inner barrel later. I got a reading of 425-35fps when I installed one in a team mates M4 with a KM inner barrel. The post that keeps the contact switch also broke after a few games. Not what I would expect from that mechbox.

[Zekk05]

Note: the pistons used in the drop in mechboxes are the red ones. ie: the ones that will break before you hit the 5000 rounds milestone. so you may want to invest in a black piston as well, just to have it onhand when the red one breaks. (read: WHEN the red one breaks, not If)

Difference between rear wired and front wired? well, look at the model. Generally speaking, rear wired M120 gearboxes are for the M16's, the front wired for M4's. The m16 rear wired box will have a non-ported cylinder for M16 length (509mm) barrels, the M4 front wired box will have a ported cylinder for M4 length barrels (363-400mm). Cylinder matching is important and will affect your guns velocity and accuracy greatly.

The one I got, the spring only shot 270 fps. it was a huge disappointment. Either I got a lemon box, or the spring was mis matched. Either way, the 120 is supposed to fire @400+ speeds, so you will definately need a new spring. (as most fields cap out at 400)

[ILLusion]

Originally Posted by Zekk05

Note: the pistons used in the drop in mechboxes are the red ones.

Not for the newer releases - the recent releases from the factory carry their new black piston.

I also still do not agree with the statement that red pistons will break within 5000 rounds. I have a 1st generation red one - the one with the so-called "messed up steel tooth"... that one has run flawlessly for well over 30,000 rounds in my first AEG I've ever owned - purchased and modified in 2002 and has pulled springs that shot anywhere from 270fps up to 475fps.

[Zekk05]

Im envious of your piston. LOL
Mine shattered pretty fast and was pretty consistent with other peoples red pistons shattering. same breaking point too.

[zener]

Well, change of plans.

I found a complete G&P gearbox for $200 shipped and decided to scoop that up. There were no Systema mechaboxes at Redwolf available and I was told that it might be a while since Systema's factory is undergoing some changes.

I've heard good things about G&P guns and I assume the complete gear box should be no different. But I'm always looking for opinion/advice so if you guys have any knowledge you are willing to share about the G&P gearboxes, please let me know. It shouldn't be any different that a Systema mechabox? (In terms of just dropping it in)

Its also rear-wired, BTW.

[Amos]

From what I've heard the mechbox if G&P's weak point (Although I don't have any 1st hand experience with G&P, I've never owned or serviced one)

You would have been better off with the systema box IMHO.

[Capt. T/O]

i have a G&P mechbox.
its reinforced, so you really dont have to worry about the mechbox itself.
the gears should also be reinforced... so no worries there.
should be aware that the trigger post is a weak point.. had mine break that too long ago as i was adjusting the hopup RIGHT 10 minutes before a game was to begin.


as good as a G&P mechbox is, i think a systema is better

[zener]

Yeah I would've liked to get a Systema mechbox but I need an AEG for the outdoor season and its killing me to have it sitting here without a mechbox.

I did a little reading an found that, yes, the G&P isn't as superior as a Systema but with a few tweaks it should be comparable. As far as I know the tappet plate is a little weak and prone to breaking. As well as there may be shimming required immediately before installation. But that was only one account.

It does have a lot of similar qualities to the Systema.


G&P Complete 7mm reinforced gear box for M4 / M4 RIS / SR16 series Marui compatible A.E.G - Full Stock. (380~440 F.P.S.)

-7mm steel bearing.
-7mm reinforced gear box.
-Complete reinforced internals: Spring guide, piston, piston head, cylinder, gear set, cylinder head, wiring, M120 spring and nozzle. (All the parts are G&P reinforced parts.)




Systema Complete Mecha-Box for M16A2/SR16, M120/Torque-Up.

Includes:
- M120 Spring
- Reinforced Gearbox with 7mm Bearing
- Teflon Cylinder Set
- Torque Up Spur Gear Set

So I'm hoping I will get similar performance to the Systema. I will continue to update this thread and let you all know when things get here and how it performs. I have a friend who has almost the exact set up as me for his AEG but he has the Systema M120 gearbox in his (We are building similar guns as we usually play together in a small squad). So I can hopefully do an in depth comparison between the two once my gun is complete.

If your worried about cracking your mechbox just get a sorbo pad

[PsycoticClown]

http://redwolfairsoft.com/redwolf/ai...l?prodID=21325

Thats the box I am getting for my gun, I am just going to get a M120 and M140. Also going to get a Trigger master, that way, depending on my role at each game, I can switch from designated marksman, shooting 420, or go semi-only with the triggermaster and be a designated sniper. Comes with a magnum motor too, supposedly one of the best motors. The M120 torque up boxes cost $220 anyways, the magnum is $79, so why not just buy the better mechbox?

[m102404]

The mechbox you bought is fine. It absolutely needs to be reshimmed and regreased properly, but the stock parts in it are (usually) fine.

Note: A M120 spring is pretty stiff, and in most M4 rifles will end up shooting over 400fps (that's the local field limits around here). If you swap to a M110 (Modify springs are fantastic), you'll be just under 400fps and your motor will love you for it.