CB180Z tail gear fix... maybe.

[bigbadwolf]

I just bought my CB180z Pro a week ago. After only 10 packs I've had to replace the forward tail gears 3 times. This last time I decided to do some closer investigation.

I've been into R/C for over 10 years but this is my first heli.

First I thought maybe there was too much play in the gears and they should be shimmed closer. No matter how thin a shim I tried to get in front of the bearing, I couldn't get the two cases together. There just is no play between the two that I can see.

I had noticed a large amount of white powder all around the area but assumed that was from the gears self destructing. Further thought made me come to the conclusion that this couldn't be. Self destructing hard plastic gears chip, not flake. I also noticed the gears looked flatter and more recessed into the case.

Upon placing the gear into the bearing it hit me... it goes in WAY too easy and since there is no real pressure holding the gear against the bearing, this is bad. Putting on a second pair of glasses (lol) I could see that I could easily spin the gear without the inside bearing sleeve turning. This IS bad.

Essentially what's happening is that the plastic is sometimes spinning instead of the bearing race causing the gear to slowly disintegrate. As this happens, the little spacer on the back begins chewing away at the back of the gear. Eventually the gears get farther and farther apart.

Now, how to add thousands of an inch to the gear sleeve without ruining it? I could oblong it by crushing it with pliers but that's a bad idea. After much thought, I grabbed my handy razor knife and made 6 slits down the gear shaft. What this does is displace some of the plastic causing a ridge. Apply some pressure but don't go too deep.

Now, the gear fits in snugly and the race spins instead of the gear.

So... I cleaned up all the plastic shrapnel on the case and threw the bird back together. After an entire pack... no signs of white residue.

Only time will tell if this has really solved the problem.

[bigbadwolf]

Pack #2... all looks good so far.

Pack #3... a bit windy here so I ended up smacking the tail on the grass a few times. Normally this would end up popping a tooth for me. However, we are still good to go!

[Ford Doctor]

I had similar problems with my tail prop gears constantly sheering teeth until I finally discovered that my gears had too much clearance. I eventually figured this out and was able to set it up much better but I did not have the same problem as you did. I will keep this in mind though and nice tip!