Flange Bearing (below main gear on shaft - sits in middle section of carbon frame)!

[dazzla777]

Hi Guys,

hoping someone can help!

Not sure why but when I throttle up, i'm getting a horrific vibration (and buzzing sound), it appears to be coming from somewhere near the main gear.

So far I have tried the following replacements to resolve it but no luck yet:

* replaced belt
* replaced tail
* replaced main shaft
* replaced blade grip screws & main blades
* replaced main gear
* replaced lower and upper collars

I think the only thing left to try is the flange bearing thats sits in the middle frame between the main gear and lower collar or another new main gear!

I noticed the vibrartion and buzzing only occurs when the main gear is spooling (so when throttle off and main shaft and head spins, its fine), this is why I believe its something to do with the main gear or flange bearing

Something to note: when I replaced the main gear, I really struggled fitting it, theres not much room between the mid and upper frames so I used bit of force to get it to snap in place (I really didn't want to have to take the frame apart when doing this!!!)

I'm wondering if although I replaced the main gear, that in doing so, I damaged it with the bit of force I applied and done soemthing to the one way bearing!

Has anyone else experienced anything like this or know what the cause is. I though it might be one of the ballbearings on either the one way bearing or the flange bearing (perhaps one or more of them got chipped/broken/ or dislogdged somehow so it doesnt run smooth/straight causing the gear/frame to vibrate and make that horrid noise!

One last thing, I did notice that when the gear spins up, before its up to speed you can see that it wobbles up and down, could this be the problem (its bent or something>), or is this normal, I wondered if it does this until the head speed is right up there so the inertia straightens out the wobble etc, an that the wobble i(at a spooling headspeed) is simply due to the one way bearing and a bit of play which is normal!

Any help would be a life saver!


Regards

Darren

[Campbellsky]

Have you recently changed the central boom assembly? I encountered the problem of having insufficient room in-between the upper and middle frame after changing to a new central boom assembly. After comparing the old and new central boom assembly side by side, I found the vertical tube, with the new CB assembly, coming from the bottom part is slightly longer. This causes the main gear being pressed very tightly and also affects the rotor head to spin freely.

[dazzla777]

Hi,

thats interesting what you say about the central boom assembly. I have replaced it with the upgrade CNC one, but it was doing the whole vibration thing before I replaced it, which makes me think its something lese causing the problem.

the head spins freely which makes me think its directly linked to the flange bearing, or the
main gear/one way bearing

Thanks for your advice though, much appreciated

Anyone else have anything else theycould share?

Darren

[stoatnchips]

Darren, i'm not sure if this is connected, but i posted about a problem with the upper frame a while back:

http://www.helifreak.com/showthread.php?t=69895&highlight=upper+frame

I really did feel that if i had run the heli for more than a couple of flights, then the flange bearing would have exploded as the main shaft was so badly mis-aligned and a bad 'Grinding' sound came from the bearing.

Just as an update, my replacement frame arrived direct from Gaui this morning.. FOC.. Great service again Gaui!! :thumbup:

Stoat