Drive Shaft Vibration

[jwelniak]

I have an 89 Comp TS6M with a PCM 351. I am getting a vibration when accelerating. I am also losing about 2-3 miles per hour in top speed. The prop appears to be fine. The strut and shaft are not loose. What should I check and what are the likely causes? Thanks for you help.

[DKJBama92Mariah]

Is your prop Nibral or Stainless? When was the last time you had it into the prop shop to be straightened and balanced. I dunno how your lake is, but I hit at least one stick ir log nearly every outing. I usually get it straightened at least once a year. It couldn't hurt. Even a small ding can cause vibration. In addition, If one of the blades is out of track (Out of position around the hub of the prop), you likely wont be able to see it and this will DEFINITELY cause vibration. You need to address this issue because that vibration causes stress on the entire boat. I found out the hard way when my driveshaft strut snapped in the middle of it because of the vibration.

Good luck and hope this helps,
DKJ

[Brian Raymond]

The alignment of the tranny output coupler and the shaft coupler should be checked every season. This is a procedure that should be done every year to verify that the face of the two couplers is within .003". There can be a vibration issue if it is out much more than that. Long term effects can lead to premature strut bushing wear and multiple packing replacements. I would deffinately have the prop. checked for balance . There is a faxable procedure on shaft alignment, contact; [email protected]. If you do not feel comfotable with this procedure, contact your dealer for an appt. Hope this helps. Brian Raymond

[Vapor-rub]

Brian,

I have a question for you since we're on the topic of drive shaft allignment.....

I was looking under my 2004 SSV the other day and noticed that the drive shaft was not centered coming out of the hull. It is noticably over to the right side, almost touching the the right side of the hole coming out of the hull.

I haven't noticed any vibration what so ever. Everything drives and sounds great. I went to my dealer to ask them about this. I even looked at some of their showroom models to see if they were the same as mine. They were not. They were all pretty close to center. I had just had my boat in the dealer's shop to replace a depth finder the day before, so I asked if they had noticed anything unusual when they had my boat out on the water testing the depth finder. They said everything was fine.

Even though my boat is a 2004, it is brand new with only 16 hours on it. The dealer told me that if anything were wrong I would definitely notice a bad vibration. I also took a look at the fitting where the drive shaft connects to the tranny. I didn't notice anything unusual there either. All looked fine. Should I be concerned with my drive shaft being off center or should I just have it checked at the end of the season when I have my year end service done?

Thanks!

[Juice75]

Originally posted by DKJBama92Mariah
I found out the hard way when my driveshaft strut snapped in the middle of it because of the vibration.

DKJ - where did you get your new drive shaft? Mine snapped in half yesterday.

[DKJBama92Mariah]

Im not sure. We had a boat dealer do the repair because i was too young and inexperienced at the time to do the work myself. Kinda funny you ask that today, because i hit a log and bent my strut yesterday. My advice would be to call Anthony Cooper at SKier's Choice. I know i'll be calling him tomorrow. His contact info is in a sticky post at the top of the service and repair forum. Good luck, you may need it, and i KNOW i will when it comes time to start this project.

One other thing. You might try and check if your strut is bent. I imagine that if you were to run a shaft through a bent stut, it would cause a pretty bad shimmy (i know mine was shaking pretty bad at anything over 2300 RPMs yesterday), and would probably cause your shaft to fail if ignored for too long.

CHeers,
DKJ

[Juice75]

It's kind of strange. My boat never vibrated at all. It has always ran smooth as glass. But I'll still definitely check everything out. I know the strut bushing needs to be replaced, so I'm doing that at the same time.

I called my local Supra dealer, and they're calling Anthony to get a price on a drive shaft. I also found a good place online that carries a lot of inboard parts for cheap. You may want to check them out for your strut.

http://www.glen-l.com/inboard/8propsh.html

Good luck with your strut.