450 Trex 450 Sport V2 helical main gear (black & White) wobble at low RPMs

[Bruno]

Trex 450 Sport V2 (fb).

This heli only has about 20 flights on it.

I have rebuilt the head/main gear after a crash.

On the bench without main blades and without the boom.

Helical main gear/pinion.

I have confirmed that all bearings (main shaft & one way) are good or new. New OWB shaft. New feathering shaft. No play in the head with 0.1 spacer, new lower Jesus bolt. Paper thick gear mesh. Top of pinion meets top of main gear (flush), Pinion is like new.

I notice at about 20% throttle that the main gear rides up and down the pinion/wobble. Any higher throttle and she is smooth as silk without any wobble. During spool down head spins indefinitely and is smooth along with tail drive gear mesh.

I have tried either the white or black main gear with the same results.

Is this typical due to the helical gears and I simply did not notice this before?

Ideas?

 

[coolgabsi]

That's just their manufacturing dye defects when they are cooled... You will see that such big plastxi parts will be inconsistent with their true flatness. You can mark the high point and press is down.. Or .... Not worry about it at all

My recommendation, if head is smooth, and no vibes at high rpm, it ain't broke

And if it ain't broke, don't fix it

 

[murankar]

One other thing I would do is raise the pinion so that it clears the top of the main gear. Not by much just enough to ensure that that pinion is above the highest spot in the main gear. This will ensure you have full contact around the entire main gear and gives you even wear too.

 

[Bruno]

Re: Trex 450 Sport V2 helical main gear (black & White) wobble at low RPMs

Update that may help others with a similar issue.

I ended up replacing the OWB which seemed to reduce the wobble quite a bit. The OWB that had been in there did not show any signs of damage and was only used maybe 20 times. So that’s kinda odd. It may have been its placement within the hub. I used a press to remove and replace the bearing with precision.

I found stripped screw in my seesaw holder (H45140T) which was translating vibration to the tail.

I also found that my tail rotor shaft was slightly bent. Replaced it with a new non-Align shaft only to determine that it was bent. Trashed the crap tail shafts (4) and replaced with Align shaft.

I also found that the tail drive belt was becoming loose resulting in needing to put some tape around the end of the boom that inserts into the tail boom housing.

All is good now. 0 vibrations.

Although I have yet to install a new set of blades.

Obviously there was plenty wrong with the heli that was contributing to a variety of vibrations.

 

[Bruno]

Installed the blades and the tracked perfect. No vibrations. Ready to fly. Need descent weather.

Pics from crash to completely black & blue...lol...

[/ATTACH]

 

[Sparse]

when i crashed my heli looked about the same, boom strike and all. its not just you it happens to everyone ! were all pro fliers until we hit the ground. LOL

 

[ChopDrifter]

This will be the heli I'll be building next. I love these old pics on the top right hand of the forum page. Really cool