Bad Vibrations :-(

[steveru]

Please help as I'm at my wits end!!

My sons Trex600 has developed a bad vibration (high frequency) which keeps breaking the boom support ends, the vertical fin wags like a happy dogs tail and the landing gear wobbles.
So far I have (in order) renewed main shaft, checked tail shaft for straightness, balanced the fan and clutch, replaced torque tube bearing (6cms forward from centre), changed main shaft bearings, exchanged main and tail rotors, renewed clutch housing bearings and checked balance of clutch bell but I cant eliminate the vibration. In desperation I swapped the motor for my OS55 which reduced the vibrations but didn't eliminate the problem.

What else is there???

[robgt]

Check the tail rotor hub as well.

Cheers,
Rob

[Supercaptaincrash]

Have you checked and changed the dampers fella? i recently changed mine for align black ones and the sleeve! also how tight are your main blades?

[smithysamrc]

You may have to ground you tail boom, because i know that some helis get static if they tail booms arn't grounded, and this static causes vibration and the static can 'lock out' the rx.

Just i thought, im probs wrong ...

[Supercaptaincrash]

sam its a nitro mate!

[smithysamrc]

sam its a nitro mate!

Oh, should have read the story to this thread first ..

[Rctintin]

As Rob said, check the tail hub. On my 700, I had some vibration probs, and when I put a piece of tape on one of the tail blades, it was out of track by a few mm. It was the hub not on the output shaft at 90 deg. In the end, I had to fit a QuickUK tail, as the hole was to big in the Align tail hub.

[rapidgaz]

i had a simlar prob a few weeks ago after i had a flybar snap mid flight on my 600, got it down ok, but after fitting a new flybar i had a strange vibe when in idle 2. found the thrust bearings had gone due to the inbalance of the head when the fly bar had snapped, so worth a look. no shakes were visible in norm when head speed was lower

[GravityKills]

remove the motor, and use a knife to clean all threadlock from the surfaces, where engine meets frame mount.
clean the non-thread end of the mounting screws (hold with pliers and turn).
This prevents a misalignment of the engine.

Check that the fan wheel is perpendicular to the main shaft.
Check that the clutch shoe sits flat on the fan wheel (unlikely if it happens with two different engines, unless it's the same fan wheel)

Mount it carefully, align the engine by pulling it down in the frame and carefully tightening the screws so that it sits as low as possible within the holes.

Then, there may be a preignition problem, especially if it idles roughly. Weather-dependent vibrations give it away.

If you changed the main rotor I assume it can't be the feathering shaft?

Another possibility: the torque tube is under pressure -> leave half a millimeter space on either side.
A slipping torque tube bearing is also possible, but I think you have ruled that out already.

[Janek]

About a year ago, I too was chasing down a high frequency vibe on one of my 600's.............it finally turned out to be a shot rear bearing in the engine, I still can't get my head round why, but it definitely was.

[stanley]

Bad vibes

I had a similar prob with my 600 nitro earlier this year , heli going great, then next time out all the symptoms your having , as i was adjusting my idle up 1 and 2 on TX i managed to put my throttle curve way too high in normal mode which shook the S--T out of mine as i increased the collective, eventually discovered my BIG mistake might be worth a look purely to eliminate from your vibration prob hope this may help