MX450 vertical tail bounce

[ratchet1974]

Great website guys !

A lot of reading has really helped me out, but I have one issue I just can't seem to get rid of. A vertical tail bounce.

I recently put together my first heli (other than rebuilding a blade CP) which is an MX450 with the following components
- 3000 KV motor from Helidirect, running a 14 tooth gear
- Align 35A speed control (6 volt output)
- Voltage regulator down to 4.8-5.3v going to the gyro (the gyro said to use 4.8v only)
- JR G500T gyro
- JR DS285 servos on the swash
- JR R790 PCM receiver
- JR XP7202 Radio
- HDS-577 digital servo on the tail from helidirect mounted on the tail boom
- Apex 2100 maH 15C lipos

Someone who's really into helis help me set this up, and get it close mechanically, so I'm pretty confident that mechanically I'm in good shape.

After just hovering around about 30-40 times in the basement, I started to notice some vertical tail bounce (bouncung up and down), as I went from forward flight to backward and vice versa. It takes a couple of seconds to steady back out. So I checked everything out & found there was quite a bit of vertical slop between the center bearing that goes around the main shaft & the swash plate. I replaced the swash & even the main shaft (although there was nothing wrong with the main shaft that was in there). It seemed to eliminate a vibration I had when I started spooling up, but I still get the vertical tail bounce. I've pulled apart / looked over just about everything, and can't seem to find anything wrong.

Has anyone else seen this issue, or can anyone give me some insight as to how to troubleshoot / get rid of this issue ?

Much appreciated !

[fedex]

heres a recent post with almost the same symptons your having

http://www.rcgroups.com/forums/showthread.php?t=658765

GL on solving your problem