This gearbox gage was developed for airsoft enthusiasts who make modifications or build their own guns.
Major Time Saver
FIRST STEP
Open gearbox and remove the gears. Place the gage as shown in image. Make sure it is seated in the bearing/bushing holes.
SECOND STEP
Put the gearbox back together. You need to install some of the screws or clamp the gearbox together. Insert a 2.5mm allen wrench through the bearing hole and back out the set screw till it makes contact with the opposite bearing. Do this for all three screws. Next open gearbox and remove the gage.
Third step
Take a pair of calipers and measure from the top of the screw to the step. as shown in the photo. Keep track of this measurement for each gear.
FORTH STEP
Take one of the gears and measure across the flats where the shims go, as shown in photo. Subtract that from the corresponding position on the gage and it gives you the shim amount. In this case it would be .035 inches.