Tail assembly Question

[Khaag]

Reassembling my tail after doing all the accepted tweaks: Boca bearings, silicone o-rings, tail shaft true-up, bushing in boom, ca c gear, etc. Spins up great with no main or tail blades. No vibes at all!

So... after statically balancing the tail blades to the extent possible, I installed them and spin things up for a dynamic balance. Must be pretty close as still no vibration! Can read the wording on the tail box just as sharp as can be. So why am I writing?

When I spin up and move the rudder back and forth the tail shaft moves laterally. It's restrained when moving to the right by the collar outside of the left bearing. The shaft slides left though when I move the rudder the other direction. Not too far, but definitely slides some. What holds the shaft in place on the right side? Appears only to be restrained by the blades and slider. Have I missed something on my reassembly? Or, is this just the way it is? Anything to worry about? It doesn't seem to be causing a problem, but doesn't appear to be right. Any ideas?

[kpod]

The right is retained by the d gear. The tail shaft has the d machined into it to a point and then past that, it is round. This creates the lip that keeps the shaft from slipping to the left. I've had two crashes where the shaft pushed about an 1/8" to the left and that was due to the shaft punching a round hole through through the d gear.

[everydayflyer]

I use a mCPX spindle brass thrust washer with step against the right flanged bearing. There is no play and I di not need to purchased $25 worth of bearings to stop the tail vibrations. This thrust washer places a preload on the tail bearings. It also spaces the D gear over closer to the C gear and thus D gear does not float side to side.

[Khaag]

Thanks everydayflyer. If I still have vibes after wrapping up the rest of this project I'll try your preload technique as well.

I just replaced the D gear and it fixed the lateral play issue I had. Apparently it's the shoulder of the flat on the shaft that holds it from sliding through the D gear that holds everything in place. My D gear must have been tight enough on the shaft to spin the tail, but a split allowed the shaft to move. Found it by holding the tail while turning the main rotor and discovered the D gear slipping. Thanks to those who read and responded.

[Liduno]

The D gear, and the aluminum sleeve that slides over the tail rotor shaft, hold the shaft from moving in one direction, the collar with the two screws in it, keep it from moving in the other direction.

If your bearings don't fit snug in the tail box they will allow some slop left to right, some people use a spacer between the bearing and D gear, some people use a spacer between the bearing and the tail shaft, some people CA the bearing into the tail box, I use floss around the bearing behind the flange, in between the flange and the tail box.

[Liduno]

I got a phone call while reading this thread and didn't refresh before I replied, Glad you figured it out.