LCT AK74 NV Response Up Custom

It's been a while since my last gearbox disassembly review. My apologies.

Let's get started with the customization. We'll go for a slightly higher rate of fire and a slightly lower muzzle velocity.

First, we'll start by selecting the parts.

Selection and procurement of custom parts

First, we selected and procured the following custom parts. Not all of them fit in the photo.

Here is a list in the most appropriate order:

Other items include various small parts and consumables, such as Tokyo Marui high-viscosity grease, GAW extreme-pressure grease, Bell Hammer extreme-pressure grease, and crimp connectors.

We will put these together.

Custom preparation

Gearbox modification

First, completely disassemble the gearbox and sand down the contact points of the sliding parts with #1000 grit sandpaper.

I diligently polish the light blue marker area.

Next, the corners of the window at the front of the gearbox are not rounded, so I'll use a rotary tool to file them down.

The finished product looks like this

I'm not just looking at it from the front, but I'm also carving it in a three-dimensional way, almost as if I'm licking the corners. I don't intend to put that much stress on it, so you might wonder if it's even necessary, but it's for my own satisfaction.

Switch wiring

Next, since we plan to convert this to a MOSFET, we will change the switch wiring to a signal wire. Since it's a signal wire, we will use thin 0.75 sq wire from Amon.

First, we'll disassemble the original switch.

Grasp the disassembled terminals with soldering clips (the wires have already been cut). Then prepare the signal wires.

Remove the original wiring using wire cutters or a soldering iron, then apply pre-solder to the terminals and signal wires.

All that's left is to connect them.

Then, simply cover it with heat shrink tubing and assemble the switch, and you're done. Since there are no positive and negative terminals for the signal wires, you can use any color of heat shrink tubing you like.

While this process is underway, the motor break-in stand is working hard to keep the motor running.

Short-stroke switch assembly

Next, we'll install the short-stroke switch. First, remove the switch pins and electrodes from the original switch.

Simply transfer the removed electrodes and pins to the short-stroke switch, and you're done.

This time, the pin size didn't match, so I attached the electrodes with adhesive. It's not a place that will be subjected to much stress, so it should be fine.

By the way, a pin punch stand like the one in the picture is very useful.

Eagle Force Maintenance Bench Block for Handguns
It's incredibly convenient to have. Moreover, it's designed for handguns but can also handle longer firearms, making it very useful. In fact, I personally didn't see the need for their M4 version.

Next, glue a spacer to the trigger to shorten its stroke. Note that there are spacers for both AK and MP5 models.

Then, we'll assemble the switch assembly and check that it works.

Move the switch to check how well the electrodes are connected. This time, no adjustment was needed.

Make sure the cutoff mechanism properly flips the switch. If you discover a mistake later, you'll develop the "no semi-automatic" syndrome.

That completes the switch setup for now.

Next, we'll compare the shape of the part to be replaced with the original part to check for any differences.

Sector gear

First up is the sector gear. It's from the Big Dragon brand, and the ratio is 16. This is my first time using it, but it's beautifully machined with no burrs or anything like that.

Spur gear

Next is the spur gear. There's nothing particularly noteworthy to say about this either.

Bevel gear

Finally, the bevel gear. This one has eight anti-reverse latches, which is great. In fact, that was the deciding factor in choosing it. The original only has four.

　

Tappet plate

Next, we'll compare the tappet plates. The Lonex one is lighter, which is a good thing. The shape of the blades is almost identical. The nozzle forward travel is also almost the same. At the right-angle section, the genuine part has better precision and reinforcing ribs. This time, we'll use the Lonex.

Now, let's do a preliminary assembly of the parts and check how it works.

There don't seem to be any interference points or other issues, so we'll proceed with this replacement part.

AOE adjustment

Now we'll adjust the AOE (Angle of Effect). First, we'll look at the current tooth contact.

This is the worst possible way to start it. Is this how it's supposed to be even with the stock parts? I'll fix it right away. Normally I would add Haneite to the cylinder head, but the LCT has a one-piece cylinder and head, which makes it difficult, so I used a GAW AOE adjuster that I had lying around. All you have to do is remove the piston head and put it in between.

But when you look at AOE again...

It's still not enough, and the sector gear and piston rack gear seem like they might interfere with each other, so I'll shave off the second and third teeth of the piston rack gear. I'll add 3mm of Haneite rubber and 1mm of plastic sheet to the piston.

Now, attach the piston head. (I decided against using the AOE adjuster.)

I also use a rotary tool to grind down the rack gear.

After scraping

Let's look at Age of Empires again here.

I think it's gotten much better.

Next, I'll check the clearance between the piston and the gearbox rails, as that's what I was concerned about.

There's quite a bit of play, so cut out strips of 0.14mm plastic sheet 2mm wide and glue them into the recesses of the piston. A brush-on type of adhesive is recommended.

・Loctite instant adhesive with brush
The brush makes it incredibly easy to use.

After checking for any looseness, everything seemed okay, so I cleaned the piston and then assembled it. This time, there was a thrust bearing inside the piston head, so I applied Bell Hammer grease and tightened it with a bolt coated with threadlocker.

Bellhammer No. 2 Gold Grease
This is a classic, top-quality grease. No. 2 has the same ingredients as No. 0 but with a higher viscosity. I primarily use it for metal-to-metal connections.

Loctite High Strength 243 Threadlocker
As a precaution, this threadlocker is corrosive to plastics, so it's best to use it only on metal.

We won't be doing a sector cut this time, so we'll apply threadlocker to the sector bolts and tighten them securely.

That completes the preparation.

Next is shim adjustment. Please refer to this for instructions on shim adjustment.

This has gotten a bit long, so I'll stop here for now.

Next time, we will continue working on the LCT AK74 customization (until it is completed).

LCT LCK74 AK74 NV AEG
I think this is one of the best electric, wooden-stocked AK74s I've ever seen.