Help! Developed vibration
 

I developed a rather significant vibration this weekend. Prop looks normal. Is it likely the coupler? Any way to determine if it is the coupler without pulling the engine? Any advice would be appreciated.

Re: Help! Developed vibration
 

What kind of setup??? Bravo, Alpha etc.? Could be the drive...

Re: Help! Developed vibration
 

Check prop shaft.

Re: Help! Developed vibration
 

It is a Bravo Drive and I am currently running close to 500 hp through it. I did hit a wing dam three weeks ago and tore up my prop pretty bad. I put another prop on it and it worked fine until this past weekend. Now it has developed the vibration. Would damage to the prop shaft be obvious? The prop spins freely out of gear with no apparent wobble.

Re: Help! Developed vibration
 

What is a wing dam? Prop shaft can get damaged from wave hopping or hitting something. The prop stops and the shaft keeps turning. Usually the vibration goes away at higher RPM's if it is the prop shaft. Take the prop off and look at the splines. If they are straight, thats not it. If the splines are twisted, get out the check book. It will be clearly obvious.

Re: Help! Developed vibration
 

Put a dial indicator on the end of the shaft to check for run out if no signs of a twist.

Re: Help! Developed vibration
 

I'm not a Bravo guy, but I'd look at your coupler. If you spin up 500hp's and stop the output abruptly, things in the middle get severely stressed. In my case, the tranny sucks up the load.

The drive "spins freely" so doesn't sound like you hurt any gears. Have you tried running it in gear on the trailer and listening for other noises in the drive?

It's possible you fractured the rubber or rivets/bolts in your coupler and it's just getting worse. Any evidence of rubber chunks in the bilge? I've seen other guys on the board suggesting a rubber dust build-up around the coupler as a sign of wear.

Good luck,
Brian

Re: Help! Developed vibration
 

Look to see if the coupler shaft wobbles. When I broke the three mounting points on my alpha coupler I saw the shaft wobble a little and didn't put 2 an 2 together right away, but when I pulled the motor out the only thing holding the coupler on where the load spreading washers. I switch to a round bravoi coupler and haven't had any problems since.

Re: Help! Developed vibration
 

Thanks for the input guys. A wing dam is a pile of rocks under the water piled in a row like a dam. They usually run perpendicular to the shore line. The Army Corps puts them there to try and control the flow of water in the Mississippi to keep the main channel from silting up. (or so I have been told). They are just below the surface. If you are paying attention you can see the disturbance at the surface of the water. Obviously I was not paying close enough attention. I was just taking off so I did not hit it at speed. Looks like I need to check the prop shaft and the coupler. If it turns out to be the prop shaft, this might just be the opportunity to shop for a used shorty drive.