Airsoft Gun Plastic Bushings

Airsoft Automatic Electric Guns (AEG's) use a set of six bushings or bearings inside the metal gearbox housing to properly align the gears and reduce the friction induced on the gear axles during operation of your gun. Some airsoft gun manufacturers install plastic bushings, some use metal bushings and others will install metal ball bearing units.

So what is wrong with plastic bushings?
They prematurely fail. How long? typically in 3 months time or less with only moderate use of your gun. In cold weather temperatures below 25F degrees the fail is even sooner as the frigid air can cause the plastic bushings to become brittle and failure is even quicker.

 The main issue with plastic bushing failure is the major collateral damage it will cause inside your gearbox when it happens. The picture above shows how a cracked plastic caused a lockup between the spur gear and bevel gear in mid cycle. The result is a stripped out spur gear that must be replaced along with the bushings.

Replace plastic bushings with metal ones ASAP. 

Airsoft Gun Bearings

Airsoft gun bearings do not fail nearly as quick as plastic bushings do, but they do fail! Bearings are great options for target shooters, bearings reduce friction inside the gearbox more than bushings and help lower the battery load on guns with high performance upgrades. The problem is, If you are a "Airsoft Gamer"  Small sand and dirt particles from normal outdoor operation get into the bearings and cause them to prematurely fail...6 months to a year.   

It can be very difficult during regular airsoft gun maintenance sessions to troubleshoot and find a bearing that is in the early stages of failure. Symptoms may include, continued fuse blowing,  stop-start motor-gear box lockup during use and then "suddenly" the gun works again, to "total gear box lockup" but when you dis-assemble the gearbox, all gearbox parts appear OK.

The above closeup photo of an airsoft gearbox shows a set of 7mm bearings that have failed. If you look at the bearing in the top right, you can see that it has experienced an epic fail. This shaft belongs to the sector gear which also controls the guns timing and is in direct contact with the piston and tappet plate. The bearing race is all that is left on the shaft and the rest of the hardened metal parts of the failed bearing are now inside this gearbox where they can cause a lot of damage with each cycle. 

If you take a look at the bearing located top left in this photo you will see that the grease from inside the gearbox has forced its way to the surface. This is a great troubleshooting indicator, this bearing has been getting very hot during use and like the bearing on the right will soon fail.

Bearings should be inspected from outside the gearbox on a regular basis for signs of heating or failure. When the gearbox is opened for yearly or semi annual maintenance, check the bearings by removing from the gearbox and placing bearings on gearshaft ends, hold bearing with your thumb and forefinger while wiggling gear back and forth with your other hand. The bearing units center metal ring called the race should have zero, or a very minimum amount of  sideways movement.

Airsoft Gun Metal Bushings

I prefer to install metal bushings in all my AEG's. They are durable and long lasting and I have not "ever" had one fail. In high torque gun applications, they can begin to elongate at the 3mm shaft axle hole, but this takes heavy usage over long periods of time.

Airsoft gun bushings and bearing sizes are categorized by the outside wall diameter (O.D.) and come in many sizes from 6mm up to 9mm in 1 millimeter increments. Each airsoft gun gearbox is specific and sizes cannot be interchanged, so it is vital to correctly measure and identify the bushing size installed in your gun before ordering airsoft gun replacement parts.

The above photo is one side of a version 3 gearbox with metal bushings installed. If you were to flip it over you would see 3 more bushings located on the other end of the gear shafts.

Metal Bushing-Bearing Installation Tips

A few, key things to keep in mind when installing metal bushings,

1) Bushing or Bearings must be seated firmly and level.

2) You Must correctly re-shim the gearbox after bushing or bearing replacement.

3) Bushings and Bearings should fit in the gearbox openings snugly. In many cases you may need to "press fit" the parts. Do not use excessive force, if light taps with a hammer on a bushing insert tool are not working then you may need to use emery cloth or a dremel tool and modify the gearbox slightly.

4) Be sure to check the bushing-bearing external face (as shown above) and the selector plate slideway on the outside of the gearbox (not shown above, other side of gearbox) for proper clearance. Binding between the selector plate and bearing-bushings can cause full or partial failure or  damage to the fire selector lever and cam as well as damaging the selector plate and causing erratic or failed selection of fire modes.

Until recently the bushing bearing type, "floating" gear sets have been the only option available. Installing this type of gear set is rather "mechanically involved" you must take apart the entire gun, remove the gear box and fully dissassemble...And that's the easy part, Re-assembly however may take much longer as the gears must be properly shimmed, and the timing must be set correctly, blah, blah blah.

Anyway, my point is the Modify company has released what they call modular gearsets. The beauty of these, they are plug n play, drop in your gearbox and ("Doctor Airsoft, you are ready to close the patient") ready. These gearsets are already bushed and shimmed and will fit most version 2 and 3 gearboxes. You have a choice of high torque, or high speed gear ratios and they are available in 6,7, and 8mm bushing-bearing sizes.

So now you know!      

Armsdealer...OUT!!