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Horrible vibration
http://www.mudmotortalk.com/mmt_v2/viewtopic.php?f=6&t=63347		 Page 1 of 1
Author:  thisisdc [ Sat Aug 22, 2015 8:53 pm ]
Post subject:  Horrible vibration
Hey all, I built my own long tail. And at first I had an Aluminium prop. Worked great no issues except the durability of props. So I upgraded and got a stainless prop from backwater. I had my buddy machine me a new threaded shaft from hydraulic ram rods which are straight and perfectly round. my setup had a 1 5/8" tube that supports the shaft. I have sealed bearings pressed into the tube that hold the shaft.
Since putting in my stainless prop on, I get a horrible vibration and noise at around 2000 rpms. It only lasts for a few hundred rpms. if I take the prop off. The vibration goes away, so it's not bearings or anything else. Has anyone had a prop balance issue like this?
Author:  Mark F. Cheney [ Sat Aug 22, 2015 10:28 pm ]
Post subject:  Re: Horrible vibration
I understand your logic about the prop and balance. However, I think it would be wise to try another prop from a different prop shop to confirm the diagnosis. Normally a balanced long tail assy. is quite quiet and smooth running through the whole rpm range. My experience with noise and vibration is either the UJ, The caged bearings ,if any, or a bent drive shaft. I have never had a out of balance prop in stainless steel.

When you get it diagnosed, please post your findings on the forum for our enlightenment.

Mark F. Cheney
Author:  Russ [ Sun Aug 23, 2015 9:56 am ]
Post subject:  Re: Horrible vibration
An out of balance prop would create vibration all the way through the rpm range. Adding a steel prop to the end instead of an aluminum one changes the harmonics of the rotating shaft, which is showing you something is wrong in the chain. Could be anything from the u joint down.
Author:  FRANKtheTAU [ Sun Aug 23, 2015 11:26 am ]
Post subject:  Re: Horrible vibration
Make sure the prop is tight against the jam nut. Sometimes you can get that noise if your prop is able to turn freely. Do you still get the vibration while running in the water? Either way I probably wouldn't worry about it unless it really is a "horrible vibration".
Author:  flint87 [ Sun Aug 23, 2015 1:13 pm ]
Post subject:  Re: Horrible vibration
Author:  thisisdc [ Sun Aug 23, 2015 1:25 pm ]
Post subject:  Re: Horrible vibration
The u joint is fine, no play in it what so ever. Bearings and shaft are brand new, less than 2 hrs on em. Yes I still had noise and vibration in the water.
Author:  thisisdc [ Sun Aug 23, 2015 1:34 pm ]
Post subject:  Re: Horrible vibration
I'm trying to upload a video but every time, it says tapatalk has stopped
Author:  Muddy ducks7 [ Sun Aug 23, 2015 10:37 pm ]
Post subject:  Re: Horrible vibration
Post pics of motor
Author:  thisisdc [ Mon Aug 24, 2015 11:56 am ]
Post subject:  Re: Horrible vibration
Author:  Takum [ Tue Aug 25, 2015 5:23 pm ]
Post subject:  Re: Horrible vibration
Is you shaft full of grease? If it is not you may want to put a zerk fitting in it and fill it full of grease this stops the harmonics in the shaft Greece is not in there for the bearings in this case.
Author:  Trousertrout [ Tue Aug 25, 2015 6:59 pm ]
Post subject:  Re: Horrible vibration
X2. Maybe the shaft has some play like throwing a hot dog down a hallway.
Author:  thisisdc [ Sun Aug 30, 2015 9:13 am ]
Post subject:  Re: Horrible vibration
Shaft is full of grease, I think the prop is just off balance
Author:  Mark F. Cheney [ Sun Aug 30, 2015 9:37 am ]
Post subject:  Re: Horrible vibration
is it possible that you bent the shaft in the changing of the prop?

Mark F. Cheney
Author:  thisisdc [ Wed Sep 02, 2015 10:41 am ]
Post subject:  Re: Horrible vibration
I'm not sure how I could bend the shaft changing the prop... I just run it now so it doesn't get into the rpms where it makes the noise. I did t know if anyone else has experienced this
Author:  quackshot [ Sat Sep 05, 2015 6:29 am ]
Post subject:  Re: Horrible vibration
Do you have a center bearing or bushing on your shaft?
Author:  kibb [ Sat Sep 05, 2015 6:57 am ]
Post subject:  Re: Horrible vibration
Author:  OlSchool [ Sat Sep 05, 2015 8:00 am ]
Post subject:  Re: Horrible vibration
Do you have a center support bearing or only on the ends of the shaft??
Author:  thisisdc [ Sat Sep 05, 2015 6:38 pm ]
Post subject:  Re: Horrible vibration
Only at ends
Author:  quackshot [ Sat Sep 05, 2015 7:15 pm ]
Post subject:  Re: Horrible vibration
That is probably your problem
Author:  thisisdc [ Wed Sep 09, 2015 6:15 pm ]
Post subject:  Re: Horrible vibration
Do other major brands have bearings in the center?
Author:  jakehawk9 [ Thu Sep 10, 2015 4:15 am ]
Post subject:  Re: Horrible vibration
Yes. Like all of them

Pretty sure most of MMT is humusexshuls in hiding
Author:  FRANKtheTAU [ Thu Sep 10, 2015 7:38 am ]
Post subject:  Re: Horrible vibration
Author:  quackshot [ Thu Sep 10, 2015 5:06 pm ]
Post subject:  Re: Horrible vibration
I think you must have a hardened balanced shaft to run without a center bearing.
Author:  mudpack [ Wed Sep 16, 2015 4:31 am ]
Post subject:  Re: Horrible vibration
I had a noticeable harmonic vibration in my Mud Buddy. Turns out it was set up by the U-joint. A U-joint increases and decreases the output rpm twice each revolution. This causes the long shaft to rotationally "spring" back and forth. I cured it by replacing the U-joint with a constant-velocity joint (CVJ). I adapted the CVJ from a 123hp water-cooled VW front axle. It has a nice rubber boot covering the whole joint and has been working perfectly for three seasons.
The next time, I'll use the CVJ from the front drive of a 500cc 4x4 Honda ATV; they are much smaller and should be more than adequately strong.
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