WE Tech M4A1 AEG

[Zack The Ripper]

Hello and happy new year to you all!

I have a question regarding the WE Tech M4A1 AEG, as the thread title may suggest. I figure there are many knowledgeable airsofters on good ol' ASC who can maybe answer my questions.

I have owned one for about 6 months and bought it as a project, but about two months after purchase and gaming it a few times for testers, I put it in my hard case and it hasn't been gamed since. I was going to sell it, however I would like to follow through with the additions and upgrading on it and game it again as it is a little beast of a gun, especially for the price.

Story aside, I know this gun is able to use 7.4V LiPos no problem; however, I want to step it up a notch and see if I can get away with using some 11.1Vs in this bitch to really crank up the tripper response and rate of fire. In doing this though, I know I could absolutely wreak havoc on the internals if not looked after and upgraded properly. Luckily for me, the gear box (Version 2) on these WE AEG's are carefully shimmed in the factory before final assembly, so I caught a small break there. The motor seems to be pretty strong and has a decent rate of fire with 9.6V NiMHs, but as I have not removed the motor thus far I don't know which model and brand it is specifically: I do know it is a long type motor though. The hop-up that came stock in the rifle is very solid and works extremely well. I have actually gotten 2 hits just beyond 150 feet if you can believe it - It fires at about 380fps with .20gs. Aside from a tight bore I don't see the need to change anything about the barrel system. I was thinking a MOSFET may be a good idea, but have heard mixed things about them as I'm sure I will on this thread.

So, rambling complete, what I am looking for is some advice on what else I will need to make this bitch 11.1V LiPo ready without destroying something on the insides. Any gun docs or persons with experience with this platform or similar platforms; please, give me any advice/thoughts on the matter so I can make an informed decision as to how to upgrade this rifle properly the first time so I can avoid spending unneeded simolians down the road.

Much appreciated, and again, happy new year!

[Off_kilter]

A proper shimming and true wired in MOSFET are what you need for 11.1 Lipos.

[Zack The Ripper]

Originally Posted by Off_kilter

A proper shimming and true wired in MOSFET are what you need for 11.1 Lipos.

Well the shim job is pretty good in the gear box, so just a MOSFET and I should be good to go?

[MaciekA]

Realistically, you yourself will be the judge of when you're "ready to go". Upgrading to powerful batteries will take you on some twists and turns and possibly a failure or two until you've stabilized your setup... At some point you will be at a game and realize your WE M4 has fired X number of rounds over N number of games and survived without failing. That's when you can put your seal of approval on it.

There are probably several dozen unique ways for your gearbox to fail due to using an 11.1V battery and MOSFET. This combination will deliver a lot of power to your motor, basically all the power that it can possibly ask for. Depending on the failure about to happen, it sometimes depends how many Amps your battery is able to put out during a runaway trigger (or short circuit) scenario or longer full auto bursts. If your motor is a strong neodymium motor and you have a battery capable of >100A of output, be prepared to get good at cleaning small shattered bits of parts out of your gearbox

Some likely "11.1V failure" weak points in your gearbox off the top of my head:

• - Piston pickup tooth (or other teeth) getting sheared, collapsing, or otherwise failing due to full auto. Fixed with a stronger piston and AoE correction. You're unlikely to get the other common piston problem, pre-engagement, since I believe you're running your WE at >400fps right now without speed gears.
• - Feeding problems caused by weak tappet plate spring (or other slow tappet movement issues) and/or caused by lack of sector delayer. Mashed BBs and jams, double feeding, lost compression issues, etc, can all happen due to this.
• - Assorted failures in and around the piston itself. Shattered piston heads due to lack of loctite/threadlock, shattered plastic spring guides, shattered plastic cylinder heads.
• - Sector gear losing teeth due to lack of AoE or weak metals.
• - Pinion gear / bevel gear failures due to less-than-perfect pinion-to-bevel alignment and or shimming.
• - Gear shaft failures due to weak metals.
• - Anti reversal latch shaft or tooth failure due to weak metal (it's crazy how often I see this one, even with high end gearboxes!).
• - Bearing failure. I just destroyed an 8mm G&P bearing a couple weeks ago during routine maintenance and testing. Inspect the race and bearings on your bearing bushings and make sure you can spot the signs that one has gone wobbly or failed on you. They seem indestructible at first but you can break one merely with the force of your hands if you know how.

What I recommend doing is just diving in and doing a few basic initial upgrades to jumpstart your project. Get your MOSFET installed (grab the GDS-4005, it's small and easy to install) and try running it with 9.6V and 7.4V batteries, just to make sure you've got the MOSFET installed correctly.

AoE: This is the biggest impact upgrade you need to do yourself that doesn't just involve throwing upgrade parts into your gearbox. When you're done with the MOSFET, the first thing to do is try to improve the survivability of your piston during high RoF fire through AoE. I recommend reading everything you can about adjusting AoE (angle of engagement) and fine-tuning your shimming (search around for pinion-to-bevel shimming or adjustment).

To summarize, you will want to make sure that your sector gear pickup tooth meets the piston pickup tooth to maximize contact surface area to spread out the force of collision and to minimize stress. During high-RoF fire, these two teeth come together with a strong force at a high speed, so if they don't come together "flat-face-to-flat-face", it is likely that one tooth will destroy the other over a short period of time. Plastic or nylon teeth get ground down or sheared off. Stronger metal teeth will usually have a sudden catastrophic failure and crack off. It can be prevented.

Here is a good picture I randomly found on Google that describes the type of failure I'm talking about:



Here's a random picture of angle of engagement between the sector and piston:



As you can see from this picture, there is an angle at which the pickup tooth of the sector can meet the pickup tooth of the piston. The setup in the picture is not ideal -- for example, it's pretty clear that the second and third tooth on the piston will have to be cut in order to accomodate the arrival of the sector gear's pickup tooth, like this:



I've drawn some dashed lines here to show what you would shave down with a Dremel tool in the pictured setup. Your setup might vary once you apply adjustment with sorbo...

Which brings me to the actual "AoE" part!:

This is somewhat down to experience and very fine details, but the angle of engagement in this picture is actually not good (good for illustration though). Let's extend some of the lines to see the angles and see why:



When these two teeth come into contact, the contact surface will more closely resemble a 1 dimensional line than a 2 dimensional plane -- a good way to aggravate any weaknesses in the piston, but also a bad way to transmit the torque of your motor to your piston. This is a very common failure point with high voltage batteries. The way you fix this angle is to move the piston back a very small amount. Usually all you have to do is install a 3/16" sorbo pad on your cylinder head and you're good to go. Often times, depending on the power of your setup, you will also want to upgrade your piston to one that is stronger. Some pistons can't handle high RoF at 400fps and above no matter how well your angle of engagement is adjusted. I recommend destroying your stock piston or any cheapies you have lying around (as a learning experience) before you throw down cash for a fancy Lonex red (or whatever).

So that's AoE.

Aside from AoE and a MOSFET installation (two tasks which will keep you more than busy enough), I would actually carefully not touch anything else in the system right now. That way if something goes wrong you have a good idea of what caused it, and you'll only be addressing one problem at a time.

I will add though that it might be useful for future purposes to determine if your motor is a neo motor vs. ferrite motor. Try checking to see if it sticks to your fridge or a steel locker door. If it does, you've got a neo motor, which is what you always want. (edit: an exceptional neo motor will attract every damned tool on your entire desk to it the instant you take it out of your motor grip.. arghh!! if you have one of these, pick up the habit of placing it in a magnet "safe zone" away from your work space every time you take it out)

[Zack The Ripper]

Thanks Maciek, greatly appreciated; this is the info I needed. Talking to Hawke he said similar things and recommended just getting the MOSFET and just gaming the gun with that until something breaks in the gear box that way I can see what was weak and what needs improving. I know that WE takes pride in the fact they shim their gear boxes very well before sending this guns out, and after putting probably about 10,000 rounds through it with 9.6V it's still shooting wonderfully. Appreciate the detail you laid out though.

As far as the motor goes it's definitely a ferrite motor. I am always getting alan kets and other bits stuck to the pistol grips on my CYMA AK and my G&G SCAR, but I don't have the same problem with my WE M4 (just double checked). Any brands/models you would recommend? Just took a look and saw this decently priced Lonex motor: http://www.airsoftstore.ca/index.php...products_id=20

[MaciekA]

Originally Posted by ZackTheRipperC

just gaming the gun with that until something breaks in the gear box that way I can see what was weak and what needs improving.

I'm a big fan of this method.. You can probe the ins and outs of a given combination of parts better that way.

That said, depending on how you run the gun you may run into the effects of AoE sooner rather than later. If you plan on full auto bursts, you should check on your piston pickup tooth after each game to observe the wear in progress and possibly anticipate that it's about to fail in the next game. When I was working on successive versions of the Diablo, I was able to see that it would fail soon.

Having a gun fail half way through a day isn't as big of a deal if you bring backups though. It's more informative that way too, since you get to do a post-mortem.

Originally Posted by ZackTheRipperC

As far as the motor goes it's definitely a ferrite motor. I am always getting alan kets and other bits stuck to the pistol grips on my CYMA AK and my G&G SCAR, but I don't have the same problem with my WE M4 (just double checked). Any brands/models you would recommend? Just took a look and saw this decently priced Lonex motor: http://www.airsoftstore.ca/index.php...products_id=20

You can't go wrong with the Lonex motor. It's got a unique sound to it and seems to handle an M120 spring and 16:1 gears with ease. Very snappy.

I'm also a big fan of the Chinese "beater" neo motors, anything included in a CYMA or JG gun is usually pretty damned good if you have it lying around the workshop. These are the motors I have occasionally run while waiting on an order of nicer stuff like the Lonex.

[Zack The Ripper]

I believe the next bits spent on me credit card will be a MOSFET and that Lonex motor. Thanks for the advice.

[MaciekA]

If you're ordering from airsoftstore you might as well grab a sorbo pad too, because that's the only other thing you're missing...

[Zack The Ripper]

Everything is ordered already. Sorbo pad with be the next on the list before I game it. Thanks for the help.

Getting a MOSFET, Lonex piston/piston head, Lonex high speed/high torque neodymium motor, silver wiring to replace the copper stuff, and changing over to deans connectors as well as bullet connectors as I will be using a PEQ box for battery storage and will make it easier to connect from inside the hand guard to the PEQ box (good old front wiring with a drop in hand guard rail system). I would rear wire it, but I want to keep an LE stock on this and with this model, rear wiring would be a bitch compared to say a KingArms M4; just the way the motor sits and the way the buffer tube is set up. Also, I like the look of the PEQ box, I'm one of those guys. I'll grab a sorbo pad before completion of this little project just for "insurance".

[Stealth]

You want us to just throw the sorbo pad in? I'll get John to throw it in if he hasn't already packed it.
You can give us an IOU or whatever. LOL

[Zack The Ripper]

Wow yes please! I'll PM you my order number.

[MaciekA]

Best service ever

[ThunderCactus]

Could just link him to the lipo thread lol

[Zack The Ripper]

Originally Posted by ThunderCactus

Could just link him to the lipo thread lol

I actually did check it out, but because this WE M4 isn't a very common rifle I wasn't sure if there were exceptions to the "norms" for using LiPos in this platform. Figured its always good to get a second or third opinion.