Maintenance Log: A well-worn Velocity Arms VA36 / JG G36 (56k warning!)

[MaciekA]

Hi guys,

After long summer of playing with the Velocity Arms VA36 (JG G36), I've decided to take a first swing at disassembling this gun, cleaning it, maintaining it, inspecting the interior for wear & tear and possibly upgrading it. I'll try to log my progress in this thread as I get these things done.

This gun has treated me really well and has never had a single jam, failure, misfire, or even mis-aim. I got it for $270 with one mag. The hop-up and feeding have been excellent the entire time -- in fact, since buying the gun I had not touched the hop-up adjustment even once. In spite of all the reliability and fun this gun has generated, the one thing I've always wondered about is the internals. I've heard a lot of horror stories about JG guns and was very curious what this gun would look like after a few dozen games and entire weekends of being passed around between various folks all firing full auto out of it for hours on end. After months of abuse, is this thing just moments away from a catastrophic failure? Is there a terrible surprise awaiting me inside ...?

There's a variety of information out there about the JG G36 and I was able to get it apart very easily with the help of a few sources (SHWELL11 on YouTube, and Evike's disassembly videos in particular are a good source. Mechbox currently reports as infected with malware so you should all avoid their tutorials).



The rifle comes apart easily, with a couple surprises. When taking this thing apart don't get confused by the missing screw where the hinged stock attaches. Mine was missing it, if your's is too then you simply won't need to remove it. Hopefully I can find an appropriate screw to use in this spot. A note about pins and screws on this gun: many of them come out very easily and I had at least one screw holding back the barrel assembly that had begun to strip. It may be worthwhile to hunt down replacement screws (and nuts) if you want this rifle to survive frequent disassembly.



Here's the gearbox and the grip removed from the body. It doesn't look like a million bucks, but feels solid. I was relieved to see the spring/piston appeared to be settled in a relaxed position. A ported cylinder is present to match with the G36C's short barrel (port is not visible in the photo, it's on the other side). The area around the port on the cylinder is a bit scratched up, but the cylinder feels solid (and heavy).



By removing the large screw out of the motor grip, tapping out the pin seen here on the left and putting the selector into semi (as well as pressing on the receiver button), the gearbox easily slides out. The gearbox is a heavy metal painted black. The wiring is a little thin for my evolving tastes but I haven't experienced any issues with resistance yet.



I was anxious to remove the motor cage from the gearbox so that I could get a look at the pinion gear. I've had so much trouble with pinion/bevel alignment with both my G&G and G&P M4s (as have my friends with their G&P M4s) that I've come to expect nasty surprises when it comes to pinion inspection. Happily as you can see above, the pinion's teeth look to be in great shape, suggesting good alignment with the bevel gear. Being inexperienced with the version 3 setup, I can only guess that maybe this has to do with the motor cage design.

On to the gearbox...



When I saw that little caramel mountain of goo, I let out a chuckle. Is this the secret to the ultra-reliable VA36? Probably not.. I'll be re-greasing this thing for sure. Overall though, the gears are in mint condition and I was very happy to see that none of the abuse had yet gotten to it.

A bushing is visible in this picture and on the left side of the gearbox, I can't tell whether they can come out or whether they're actually part of the gearbox. On the right-hand side of the shell, they come out rather easily and are metal. Which brings me to the right-hand side of the gearbox...



I don't know how I didn't notice this at first but when I looked over I laughed again. Awesome. I'll never run out of grease!

Back to the gears.



Removing the sector reveals that it is gradually polishing the surface of the cut-off lever to a fine chrome finish. Oh well. I was bound to find SOME skeletons in this closet, and at least now while I'm already in here, I'll actually have something more fun to do than just cleaning and re-greasing. On that note: I didn't find any shims in this gun at all, but it's been a remarkably quiet gun for the lack of shims. I wonder if the mountains of grease is how JG gets around the lack of shimming. In any case, it didn't hurt performance or reliability for a whole summer. Not bad.

Heading up north towards the spring guide:



I think I'll be replacing this with a metal bearing spring guide. In the absence of things to fix, I gotta pimp something out right?

Nozzle:



The nozzle is plastic, and has a nuclear-symbol opening rather than circular opening like my other nozzles. Perhaps this helps guide the airflow to the middle of the BB in the hopup chamber? While I'm discussing springs and nozzles, I might as well mention that this gun has chronographed a consistent 360fps at several games. I suspect the spring is probably an M110.

Piston:



The piston is in great shape and the teeth look to be in good condition with no major wear (the picture masks it a bit with all the grease). The spring seems to be attached to the inside of the piston, which seems odd to me compared to the other rifles I have.

Wrapping up, here are some goals for this gearbox:

1) Upgrade the spring guide, maybe the piston and piston head.
2) Re-grease and re-shim the gearbox to reduce the wear I've seen.
3) Rewire the gun for Deans as I continue to standardize on Deans-wired batteries across my collection.

If anyone has any requests for pictures, or suggestions for project ideas, I'm all ears. I'll try to post progress / updates here.

[klondike_bar]

looks in nice shape! i recently purchased a VA36 as my first gun, and have wondered too how well everything inside is gonna run over time. its good to see that these guns are fairly solid!

i dont know much about the oil/grease but id agree that your caremelized grease could likely do with an update

[MaciekA]

Update:

I've cleaned the internals up considerably, did some shimming, re-greased and reassembled. After that I chrono'd it at 365 - 367 fps.

The noise level seems to have dropped a tiny bit due to less rubbing on the cutoff lever. I also tried to get more clearance between the gears than I saw before.

I didn't measure RoF before doing this work but it feels like it's dropped a bit, probably due to my shimming. I will probably give it another try some time this week to see if I can get the best balance between RoF and play / contact.

Some notes from re-assembly:

1) This thing is really tough to get back together compared to a V2. The trigger is really really tricky to keep in place while sealing the box and holding everything else together. I feel like I've completed a rite of passage just by getting that trigger spring and those two trigger shafts to align while holding the main spring, cylinder and just about everything else with my greasy hands. I read warnings on various forums, and they were all correct. Prepare for some hair-pulling...

2) If you take this thing apart make sure to take lots of pictures of how the wiring is set up or it will be hard to put back together. If the gearbox is jammed into the lower receiver without care, the wires will probably strip.

3) It appears to be extremely easy to bend or damage the selector plate during re-assembly. I had to go very slowly and watch both sides of the gearbox slide in to ensure everything "slotted in" correctly.

4) Aside from the gearbox shell itself, the motor cage seems like it might be the first thing to go if anything metal were to "go" on this gun. The bottom of the two halves of the cage has one side that bends out ever so slightly and has the seam open into a 1mm gap when the gearbox is out of the grip (I suspect the two halves are pressed together while in the grip. Hard to say).

[FoxhoundNB]

It's nice to see one of the low-end brands holding up well. I have a Kalashnikov (D-Boys?)AK-104 that still looks brand new inside after 2 seasons of very regular use (mostly as a lender)

Honestly I'm often surprised at the quality of some of the low-end manufacturers.

[AngelusNex]

Originally Posted by FoxhoundNB

It's nice to see one of the low-end brands holding up well. I have a Kalashnikov (D-Boys?)AK-104 that still looks brand new inside after 2 seasons of very regular use (mostly as a lender)

Honestly I'm often surprised at the quality of some of the low-end manufacturers.

thats the thing, They are pretty much the same as high end. Though, with high end you're paying for quality control, you're more likely going to get a perfectly working gun then you are with a low end gun... however, lately, I've been seeing allot of "high-end" guns being shitty (G&P, CA and TMs that are crap and break down like crazy out of the box)

[iKliiu]

Follow Gear Shimming Tutorial - YouTube.

Also, I'd suggest you adjust the AOE. These china guns can last forever if basic tuneup is done.

[MaciekA]

Originally Posted by AngelusNex

(G&P, CA and TMs that are crap and break down like crazy out of the box)

This is true, both my G&P and my G&G lasted no longer than 5 minutes out of the box. Overall though they've been fairly easy (for me anyway) to keep in a high-performing, high-durability state. I'll try my best with this G36, but we'll see.

[MaciekA]

Hey guys, small update.

Last week I shimmed this gun (since it came with no shims and the sector was making contact with the cutoff lever) but I wasn't terribly impressed with the results sound-wise and the RoF seemed to have dropped. Today I went ahead and stripped the gearbox again, gave it a good clean and started with a thinner set of shims, and also used some new grease (Modify gear grease with Teflon). I tried my best to spend some time testing out each shim config as I went, testing for play and re-sealing the gearbox with each shim application.

I'm really pleased with the results, the sound, the responsiveness of trigger, and the improved RoF. Here's a video of me testing a 7.4V LiPo and a 9.6V NiMH battery with the updated gearbox:

JG G36 (Velocity Arms VA36) Testing After Shimming and Re-Grease - YouTube


You'll notice that my fire mode selector gets rattled around as the gun fires, which is not a new issue. I'm not sure how to fix this. If anyone has any suggestions, I'd love to hear them.

[SuperHog]

Is the gauge marked on the wires? I have seen wires with very thin insulation and large wire conductor in it.

Looks like it is running smooth and quite from the video.

Check the tension of the spring detent on the selector. It shouldn't rotate during firing at all.

[Kos-Mos]

G36s selectors are held on each side by only a grub screw. I guess they are just not seated properly. You can remove them and make sure to apply a lot of pressure between the internal gear and the selector (need to have mechbox removed). That fixed my issue with my older KWA G36

[MaciekA]

Originally Posted by SuperHog

Is the gauge marked on the wires? I have seen wires with very thin insulation and large wire conductor in it.

Hmm, I didn't think to check it, I'll be sure to when I'm back in there.

The wiring does seem pretty thin and it sucks to have it travel through multiple sets of Tamiya connectors to reach the battery, but either way I haven't even had a hint of any heat from the motor, wires, or connectors on this gun. When using Tamiya with my G&G M4, I can detect heat on the connectors, (using the G&P M120 motor), but on this G36, nothing of the sort. The motor doesn't feel as thirsty.

If I ever swap out the motor in this thing, replacing the wiring will definitely be on my hit list.

[MaciekA]

Originally Posted by Kos-Mos

G36s selectors are held on each side by only a grub screw. I guess they are just not seated properly. You can remove them and make sure to apply a lot of pressure between the internal gear and the selector (need to have mechbox removed). That fixed my issue with my older KWA G36

Thanks for the tip, I'll try this next time I sit down with it.

[MaciekA]

update:

Re-assembled the gun and ran it through the chronograph with 7.4V lipo, 8.4V NiMH, and 9.6V NiMH batteries.

JG G36 (Velocity Arms VA36) Chrono After Maintenance - YouTube

[Styrak]

That's nice and consistent.

[MaciekA]

Update:

It's been a while since my last update but I've been tinkering with this gun on ever since my last update, and I've toyed with many things.

Swapping the Bushings and replacing the gears

Contrary to my initial report earlier in this thread, this gun has Nylon 6mm bushings, not metal ones as I initially thought, and not 7mm as stated on the VA website. Hopefully they update their listing. Anyway, it took me a while to notice this as I didn't inspect the bushings very closely. I've read that plastic bushings are the first thing to go in guns firing beyond stock Japanese limits, and this thing is firing around 360fps, so I figured I'd get metal bushings.

This actually turned out to be trickier than I expected. In this gearbox, most of the bushing holes can be described as "innies", with a small inset circle for the bushing to rest in, but the sector gear's hole is an "outie", with an outset circle rising above the surface of the gearbox shell. This was fine with plastic bushings that were able to slightly deform and squeeze, but with metal bushings, it actually made the stock sector gear a tight squeeze with considerable friction against the bushings. Shimming to raise or lower the gear was thus impossible (since there's no extra room). The raised outline represented a decent amount of thickness, so I decided to risk it and file it down flush with the gearbox shell, which helped quite a bit.

To give myself even more room, I swapped the gears for a G&G set which had ever so slightly more wiggle room. I'm happy with the shimming now, easy/free rotation with very little play.

New selector plate

Tossed out the stock selector plate (which had bent out of shape somewhat from my carelessness) for a new one. Works great.

Metal Bearing Spring Guide

For the heck of it, decided to replace the stock plastic spring guide and throw in a metal one with a ball bearing washer. I'm re-thinking this decision due to possibly having slightly less space for the piston+spring to be pulled back towards the rear of the gearbox. Not sure how much of an issue that could be.

Checked AoE / piston tooth removal

After some more usage of this rifle and closer inspection, there was a very slight amount of wear on the piston from the sector gear engaging the second-to-last tooth, so I filed it down. Tooth engagement looks a tad better now.

Modify G36 Cylinder Set


I gave the Modify G36 cylinder set from airsoft parts a whirl. It comes with a nice piston, piston head, cylinder, and cylinder head. All of these parts look to be really nicely made. Unfortunately, the cylinder head is completely incompatible with this gearbox shell and seems to be made for some other G36 gearbox shell, so now I have an extra cylinder set lying around. If you have a V36 or a JG G36, don't try this cylinder set, it won't work. Live and learn I guess .

G&P M120 small type motor


I decided to try one of these in this to see how it would do, but even with good bevel to pinion alignment, I had trouble making this combination work. The motor seemed to get fairly hot, even though I could move the shimmed gears with a feather touch. When the gearbox did cycle, it would get a good RoF and feel snappy. Occasionally though, it would seize (with the spring fully compressed) and the motor would get hot. Pulling the trigger would only jiggle the piston a little bit but not complete the cycle.

I also observed some blue arcing inside of the motor itself. I've gone back to the stock JG motor, and it has absolutely none of these heating or cycling issues. I'm still scratching my head over that, because I don't see why it would be the motor's fault -- especially since I took a lot of time with motor height adjustment too.

The current incarnation of this rifle, with metal bushings, better shim job, spring bearing guide and G&G stock gear set, remains firing in the mid 360s.