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Wildcards
03-02-2012, 08:49 PM
In the boom on the torque tube?? what are you guys using? I am starting the slow rebuild and I have an extra bearing, does this actually help with vibs at all?

snjbird
03-02-2012, 09:14 PM
I use two...

Wildcards
03-02-2012, 10:15 PM
I use two...
And so did I

duytang
03-02-2012, 10:52 PM
did you guys notice any differences with having 2 bearings?

Deet
03-02-2012, 11:05 PM
One

Always have, in the specified spot

Never a vibe issue, never failed.

Every vibe issue I have tracked down has never been solved by adding another bearing to the TT

pxpep
03-03-2012, 01:58 AM
One

Always have, in the specified spot

Never a vibe issue, never failed.

Every vibe issue I have tracked down has never been solved by adding another bearing to the TT

This is so true.
Why not 3 bearings ot maybe 4?

wanderer56
03-03-2012, 06:09 AM
Of the 3 TT shafts I've purchased since converting, not one has been very straight. And for the money, I'm not going to do the "Roll it on a flat surface to straighten it out" technique.

Mateyhv
03-03-2012, 07:41 AM
Tail belt is the way to go, you will never look back and spend money again :rotf

Deet
03-03-2012, 03:21 PM
I have never seen a bent TT , new in packet

Wildcards
03-03-2012, 05:54 PM
I just never check. I like to assume its straight

Deet
03-03-2012, 08:18 PM
even if it is bent, 2 bearings can't fix that

tomd27858
03-03-2012, 08:49 PM
One

Always have, in the specified spot

Never a vibe issue, never failed.

Every vibe issue I have tracked down has never been solved by adding another bearing to the TT

same here.

NRPY
03-03-2012, 09:07 PM
Since I was curious, and my 500 Pro is equipped with an SK-720, I tested the "two TT bearings reduces vibes" theory. The attached screenshots are from the SK-720's vibration spectrum analyzer. The big peak in each plot corresponds to the tail rotor RPM, which is where tail vibes show up.

Bottom line: no significant difference in tail vibes with an additional TT bearing. In fact, two TT bearings resulted in slightly higher vibes, but the results are close enough such the difference can be ignored.

Tomy.
03-04-2012, 01:02 AM
I had a strange noise a few months back so I added another bearing but it did not help (turned out at the end it was old Boca beraings in the motor). I did not take it out but I don't think there's a significant advantage. I never had a bent torque tube, always checked when pulled a new one from the package.
As for the belt, it was the part that cost me the highest repair cost ever when broke so I ditched the belt setup and never looked back. YMMV.