Thread: Discussion CB100 Tail Wag
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Old Feb 15, 2010, 10:36 AM
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Aachen Germany
Joined Dec 2007
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CB100 Tail Wag

Tail wagging every 5-10 seconds? Wagging cures of the CB100 been discussed and posted and re-discussed - thought I'd share my wag and eventual cure - unfortunately the drop of oil on the tail motor didn't work this time. Note-1: One drop in the hole where the wires come out works better than half a can everywhere else. Note-2: All of below applies to crash-a-lots and hardly ever. Note-3: The CB100 tail motor doesn't last forever. Note-4: Don't mess with the gyro unless all else fails.

Main Gear:
A couple teeth missing on the main gear or a few worn teeth can cause tail wag. Why? Because the tail motor runs independently of the main motor - if the main rotor is hiccuping very slightly it has the same effect as the tail rotor hiccuping. Hint: A x10 jewelers loupe and bright light works better than squinting in the dark.

Pinion Mesh:
The main motor pinion mesh very critical. A tiny bit of slip and the tail is all over the place. Not too tight and not too loose. Loosen the screws slightly on the motor and gently push the motor pinion against the main gear and turn the rotor by hand. You should be able to feel the notching of the motor without any other resistance. Again the x10 loupe and bright light helps to visually see the mesh. Tighten the screws after.

Tail Rotor:
Check the tail rotor and make sure it is not slipping. Verify the tail rotor pins are engaged in the two small holes of the bell housing of the motor.

Tail Motor Wires:
Check the 3 tiny motor wires by gently pulling on each side of the shrink tubing. If a wire breaks loose possibly you had a bad solder connection. Resolder as necessary. Hint: Use a very small tip iron - 20 watts is 10 watts more than you need.

Tail Motor:
Replace the tail motor. The motor is press fit into the tail holder assembly and secured with one screw. Most difficult part of replacing the motor is soldering those itty-bitty wires. If the motor turns in the wrong direction (the leading edge of the tail rotor must turn UP into the wash of the main rotor) reverse the plug on the tail rotor ESC. Hint: the leading edge of the tail rotor is closest to the shaft of the motor.

Flight test after performing each step - new tail motor fixed mine. Tail wag is history. Good thing - I was running out of ideas. Please add any of your own.

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