Modify Gearbox Shim Set Mixed

Modify Gearbox Shim Set Mixed


In stock



Modify Gearbox Shim Set

4 types: 24pcs in total ( Mini types: 0.1mm*6, 0.15mm*6 / Standard types: 0.3mm*6, 0.5mm*6 )

Precisely shimming the gearbox minimizes the up-and-down play of gears to reduce noise and enhance smooth operation, as well as inter-gear efficiency to reduce load.

  1. To adjust the gap between the gears and gearbox housing.
  2. To adjust the gap or height between the 3 gears (sector gear, spur gear, and bevel gear) to minimize friction against the gearbox.

Note Gears must not be shimmed too tightly to avoid over-stressing the motor resulting in damage.

Why Shim the Gearbox?

  • To prevent gears from rubbing any other part of the gearbox, where contact should only occur between the gear shafts and the ball bearings, the cogs of the gears, the sector gear and the piston, the cam of the sector gear, and the cut-off lever; the sector gear and the tappet plate.
  • To reduce friction between gears and ball bearings. To reduce friction between gear wheel sides and gearbox, high-quality AEG shims of the suitable gauge must be used to enable adjustment of the gear gap for minimal friction.
  • To adjust gears to achieve maximized direct contact against cogs of another gear so as to realize optimal torque transfer between gear and piston as well as cam of tappet plate and cut-off lever.


  • Material: Stainless steel
  • 4 types: 24pcs in total ( 0.1mm*6, 0.15mm*6, 0.3mm*6, 0.5mm*6 )
  • Small outer diameter is best to use with ball bearings

Don't forget - if you aren't comfortable or experienced enough to carry out your own weapon servicing, repairs or upgrades, we can help! We have experienced airsoft technicians in-store and can do the work for you. You can even book a service with us online by clicking the link below!

Book a Gun Service.

To buy an airsoft weapon in the UK you must have a valid airsoft defence.

This is not a licence, it is basically just proof that you intend to buy an airsoft weapon for use in airsoft.

An airsoft defence could be a UKARA or membership with the British Airsoft Club, and various other forms of defence.

You can only obtain an airsoft defence once you are over the age of 18.

To get an airsoft defence the law is that you should play at least 3 games of airsoft, and that you must have been playing for at least two months.
You can still buy an airsoft gun without a defence, provided you are 18 or older. If you choose to do this we would, by law, two tone (paint in a bright colour) parts of your chosen weapon. This is because an airsoft gun is considered a RIF aka Realistic Imitation Firearm, because they are so close to the real steel, whereas when you paint parts of it in a bright colour it becomes an IF aka Imitation Firearm. The reason being that the bright colours make it look less realistic to the public, and therefor less likely to be mistaken as real, were it to be used for any other purpose than airsoft.

When you order a gun from us you will need to add your defence details in the comments section of the cart. If you do not have a defence you will need to write the colour that you wish to be used for two toning your airsoft weapon.

Here is what's stated in the VCRA (Violent Crime Reduction) Act:

For airsoft skirmishing, the Association of British Airsoft is putting in place arrangements to allow retailers to check that individual purchasers are members of a genuine skirmishing club or site. The key elements of these arrangements are:
1. new players must play at least 3 (three) times in a period of not less than two months before being offered membership
2. membership cards with a photograph and recognised format will be issued for production to retailers
3. A central database will be set up for retailers to cross-check a purchaser’s details
4. member’s entry on the database will be deleted if unused for 12 months.
The defence for airsoft skirmishing can apply to individual players because their purchase of realistic imitation firearms for this purpose is considered part of the “holding” of a skirmishing event.
Size Chart