The DEFINITIVE Guide to Shimming You Airsoft Gearbox | AIRSOFT TECH

Do we really need another shimming guide?...

A friend of mine keeps asking me a very serious tech question that - quite frankly - I've never seen answered anywhere:

"Which brand makes the best shims?"

Obviously, the answer is Prometheus, because they're a bit more expensive than some other shims.

"Do we really need another shimming guide?"

Probably not, but Airsofters and techs tend to obsess over shimming their AEG. Current draw, rate of fire, wear-and-tear, and the noise of an AEG can all sometimes be directly attributed to shimming.

The problem is that the "tried-and-tested" techniques of shimming seen in guides all over the internet that are supposed to work perfectly every time - quite simply - don't. This topic has been discussed online to death. But my personal experience is that most guides don't stress the most salient points.

I want to share with you my simple and reliable way to shim any AEG gearbox. I'll be using an E&C V2 gearbox in a completely standard configuration, but most of the principles are the same regardless of brand, gearbox version, replica, and gear set.

Keep reading to find the step-by-step process I follow for how to shim an airsoft gearbox.

Why do we shim our airsoft gearboxes?

Shimming is the process of adding metal washers above and below the gears in an airsoft gearbox so that they spin freely without moving along their axles.

Well shimmed gears should be quiet, not bind together, spin freely with little effort, and have enough tooth contact between gears without the faces of the gears contacting and creating friction as they cycle.

The goals and intent of what we're actually trying to do by shimming the gears of an airsoft gearbox are:

1. Reduce gearbox noise, motor heat, and improve battery efficiency

2. Prevent premature wear and damage to the gears, motor, and piston

3. Improve battery life, decrease the likelihood of gearbox jams, and (in extreme breakdowns) reduce the likelihood of your LiPo battery from exploding.

Good shimming means your AEG will last longer, require less maintenance, suffer fewer breakdowns, and perform much more reliably. It's as simple as that.

If this doesn’t sound like your cup of tea but you’re looking for a gearbox upgrade, get in touch with me below:

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Getting your Airsoft Gearbox ready to shim

If you're new to ripping open AEGs, get yourself a decent soldering mat like my blue silicone one. I can separate out parts and keep things neat so screws don't go missing. The squares on the right hand side are also great to keep stacks of shims in place for the gears so that I don't lose them once the gear is shimmed but we haven't lubed up yet.

Three tips to get you started: