TREX 500 Helicopter - 05 - Vibrations - Part II - Rotor Head Assembly

In Video #4, I noticed the tail was bobbing quite a bit up and down. I thought there might be something wrong with the tail.

However, digging a little deeper, I'm noticing the main rotor head assembly is wobbling side to side. I verified that the main shaft is okay, it does not wobble.

Take a look at the video. It appears that the main rotor head assembly is the issue. This is an expensive part so I don't want to replace it unnecessarily.

I found an interesting forum posting on someone with the same problem with a TREX 450, see:

http://www.rcgroups.com/forums/showthread.php?t=1036839

Let me know what you think.

Thanks
Gary

Category:

Howto & Style

Tags:

• remote
• control
• helicopter
• trex
• 500
• head
• rotor
• wobble
• wobbling
• vibrating

[xkadet]

did you ever resolve the problem gary? It looks like the head is drilled off axis or the tip of the main shaft is slightly bent. I would replace the head sleeve and see if this solves the problem. It means setting up everything again, but I don't see the main shaft wobbleing, just the head, and that says head sleeve to me. Either damaged or machined poorly. If you did find the problem, please let us know.

[garypuppa]

@xkadet I replaced the main rotor block and that solved it. Check out video #6 on my YouTube channel.

Thanks

Gary

[imprint2finished]

i think its your main rotor housing that is causing all the vibration... i had the same problem before, i landed a little bit too hard one time and thats were it all started, i tried everything to make it snug fit with the shaft but no success, sometimes the problem would go away at high rpm but i just got fed up with it and i bought a new main rotor housing... problem was solved....

[garypuppa]

@imprint2finished I replaced the main rotor block and that solved it. Check out video #6 on my YouTube channel.

Thanks

Gary

[garypuppa]

@imprint2finished I replaced the main rotor block and that solved it. Check out video #6 on my YouTube channel.

Thanks

Gary

[leebethell]

have u replaced the main shaft??? if so looks like u need a new head

[garypuppa]

@leebethell I replaced the main rotor block and that solved it. Check out video #6 on my YouTube channel.

Thanks

Gary

[vespira]

I have an EXI-250 that is almost a 100% Trex clone. I noticed the head button was wobbling even when turning the main gear by hand. I pulled the main rotor block and found that the shaft was straight as an arrow. I then put the main rotor block onto an appropriately sized drill bit and spun it up... wobbled like mad. :/ I replaced the main rotor block with one from align and the problem was resolved. Looks like you came to the same conclusion on a bigger bird. Seems to be a design flaw.

[surfgoof]

This is a great idea for solving vibrations, if you view it frame by frame. This will help me solve my shakey head, thanks.

[archienook]

it really looks like your upper head block its not straight enough the main shaft is straight enough u can see it on the video the wobbling just start from the main head. look like you have a defective head block from the factory if this is brand new, or maybe u can ask a replacement before you replace other parts,

[xkadet]

Thanks for the input. Looks like I have some work to do myself. Best regards,

[garypuppa]

@xkadet - I purchased a new main rotor head assembly last week. I'm going to install it this weekend and provide an update.