For you competitive T-Jet racers out there, here is an article about preparation of the top gear set... particularly if you are using a mass produced out of the box gear set as opposed to a precision CNC machined set like the ones you can get from RT-HO. When preparing a car for racing you basically need to think about four things... alignment/squareness, friction, current, vibration. This sounds pretty simple from a high altitude point of view, but, these things are intertwined in every part of preparing competitive T-Jet. If you are interested in how it pertains to the top gear set with respect to friction then click on the read more link below.
The following statement is what started it all. "The first thing I do to a mass produced gear set is de-burr the gears using my Dremel and brass wire brush wheel. I do not want to use anything harder than the brass gears therefor the brass brush wheel." This is where I found out NOT to do this if at all possible because it leaves scratches on the face of the teeth that causes more harm than good.
Lap the gears, yes. When the gears have been lapped and worked in together, then polish the wear side of them.You want to remove the burr on the bottom of the gear surface that rides on the top plate. You also do NOT want to remove any brass from the top of the gears because you want to keep them as thick as possible so they run square with the next gear. Next, never polish the idler hole or gear axes hole. It's a wearable surface let's not speed that along. Let the gear wear to the top plate.
Thanks again for sharing Scott Udave!! Much appreciated!!