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How to get rid of vibration of the flex shaft?

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How to get rid of vibration of the flex shaft?

Old 01-05-2019, 06:39 PM
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Default How to get rid of vibration of the flex shaft?

Hi, Boaters

When I spin the prop by a hand to see if the flex shaft wobbles near the coupling, I do not see any wobble and the flex shaft, coupling, and motor are in the straight alignment.

However, around the half throttle, the flex shaft wobbles with vibration, and then, at the higher rpm, wobbling and vibration are much decreased.

What causes this? What will be the solution for wobbling and vibration at the mid-rpm? Advanced boaters' advice will be greatly appreciated. Here is a picture of the boat set up.
Thanks for your attention.
Old 01-06-2019, 10:05 PM
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Is the prop balanced?
Is there play between the shaft in the strut or motor bushings?
Are the screws securing the strut, motor and motor mount all tight?
These three are usually where I would start looking
Old 07-15-2019, 02:05 PM
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Are you using the flex shaft in the straight tube ?
Old 07-18-2019, 02:21 PM
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An old thread.... The problem is most likely running the motor out of the water. Many newbies think that it is okay to run the motor for several seconds on the bench, this is NOT okay! Out of the water just blip the throttle to check rotation, any more will cause vibration. This vibration (assuming a reasonably balanced prop) will disappear on the water. Donít do it!

Old 07-22-2019, 03:25 AM
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I must be lucky b/c I don't get that with my #Sonicwake 36'' Self-Righting Brushless Deep-V but then again my boat is a few months old only.
Old 07-24-2019, 01:38 AM
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Grease the shaft and run it in the water where you have resistance and I'm sure you problem is gone! :O)

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