I will be referring to different parts of the crown gear throughout this article, so let's get them identified and out of the way. For this article I will be referring to two different parts of the crown gear, the head of the gear and the tail of the gear. See the pictures below.
If you look closer at the pictures above you will notice that the gear on the right has a more prominent head than the gear on the left. The gear on the left is more like the standard crown gear for the T-Jet. The gear on the right is a RT-HO gear. You can build up the head of the standard gear using washers if you like. It usually only takes one. The picture below has two for demonstration purposes only. (See the below picture)
Everyone has their preferences about the the type of crown gear to use, for me, I like the RT-HO because of the prominent gear head. First it protects the gear teeth from the chassis, and second I only have to worry about adding washers to the tail side of the gear when trying to remove gear lash/play.
When I install a crown gear I use a wheel press, a guide rod, tweezers, and a home made guide tool. The guide tool was easy to make. I used a handle from a disposable sponge brush and an AFX Magnatraction front axle with the head ground down just enough to fit through the crown gear. Note: Do Not grind the head away completely.
The high level concept here is I use the guide tool to get the washers and crown gear aligned and in the slot correctly. While the guide tool is aligning the holes of the washers and crown gear it is then used to pilot the guide rod. Once the guide rod is in place I check the gear lash/play to see if I need to add or remove a washer. Once I feel that I have the correct washer/crown gear combination I then use the guide rod to pilot the actual axle.
I insert the guide tool through the chassis hole closest to the crown gear slot. I push it all the way through and then slide my washers onto the tool.
I insert the guide tool through the chassis hole closest to the crown gear slot. I push it all the way through and then slide my washers onto the tool.
I then pull the washers with the tool to the chassis. This is why you DO NOT want to grind the head completely off.
I then snap the crown gear in beside the tool and push the tool forward through the crown gear hole.
I now insert the guide rod in the other chassis hole and use the guide tool to pilot the guide rod through the crown gear, washers and the other side of the chassis. You will have to learn to "feel" your way through this. After a while it becomes easy.
I use a guide rod that is 0.055 inches in diameter. It slides through the chassis holes and crown gear hole easily and minimizes the gear slop when checking for gear lash. When the guide rod is in position then check the lash/play in the crown gear using a pair of tweezers. I turn the crown gear about 1/4 turn and check the gear play. I repeat this until I rotate the gear completely. This is also where you will have to learn to "feel" your way through. This is also where I decide to either add or remove a washer. I have different width washers from as large as 0.015 to 0.003 of an inch.
When all is well with the gear lash it is now time to install the axle. The guide rod will pilot the racing axle through the washers and crown gear. For this process you will need the wheel press. See the picture below to set this up.
Now the last part of the installation is to press the racing axle through the crown gear, washers, and chassis axle hole. To do this you will put you thumb and forefinger together and squeeze the guide rod with one hand and with the other hand you will turn the knob on the wheel press. By doing this you will keep the ends of the racing axle and the guide rod together tightly when moving through the holes in the crown gear, washers, and chassis.
As with anything no one way is the right way. This is how I install a crown gear when trying to remove gear lash/play. Hope this will help some and give some some ideas to move forward. Anyway, may your crowns run straight and freely without any lash!! :-)