View Full Version : Steering vibration issue...any thoughts?

11-04-2011, 07:48 AM
Roughly 3 months ago I had an incident with my prop that resulted in the rudder being slammed to the side breaking the steering clevis bolt. This unfortunately happened at roughly 40mph with a footer in tow and nobody was injured but you can imagine the force that was against the rudder.

The boat is an 08 PS197 w/MCX and gear reduction tranny.
So, with the help of Eric from OJ, we put a new prop on the boat, a 13x14.5 which replaced the 13.7x15 that was previously on there. The 13.7x15 was what the TT boats were running back in 08 from what I recall and the newer 13x14.5 is what they changed to.

OK, so the problem is that with the 13x14.5 on the boat I get a vibration/shudder back thru the steering wheel at or above roughly 4000rpm's. The shudder is the exact same as if you were power loading your boat on the trailer. The problem goes away if I make a slight left or right hand turn but is very prominent if simply driving straight. My dealer, who replaced the clevis bolt, has re-checked everything to make certain the steering is OK and Eric was kind enough to send me another 13x14.5 prop to test so that I could put my own mind to rest that it may be a prop issue, and the issue persists.

So, my guess is that the new prop is causing some sort of additional cavitation at the higher RPM range that my previous prop was not but I am curious to know if any of the TT guys or people with the same set-up running the 13x14.5 experience this issue as you approach WOT? I can start to feel a slight hint of this at 3680rpm but it does not become pronounced until you are in the 4k range.

I absolutely love the new prop from Eric as it give a better holeshot and more top end (+3 or 4 mph) however, the vibration issue concerns me and I would think that it would lead to further issues down the road if I continue to run it.

I am open to thoughts.

11-04-2011, 08:12 AM
Things to check/recheck since the vibration is still there with 2 different props:

-prop shaft bent? check with dial indicator
-engine alignment?
-bent strut?

11-04-2011, 08:25 AM
I'd put my money on a bent shaft... How easy is the prop to turn by hand?
Could be that all 3 need work/replaced.

Table Rocker
11-04-2011, 09:12 AM
Can you tell us more about the incident?

Did you change out the rudder? Was the rudder port damaged?

11-04-2011, 09:19 AM
I vote for slight rudder bend since it occurs predominately within a certain speed range.

11-04-2011, 12:25 PM
All good thoughts but all pose the same question: If the rudder, strut or shaft were bent, wouldn't the vibration exist at all speeds and be present regardless of which way the wheel is turned?

The incident was that a blade came off of the 4-blade prop while going 40+mph which resulted in the a massive imbalance of water eing thrust back against the rudder snapping the clevis bolt and throwing the boat into a right-hand powerturn. Fortunately we were in the middle of a smooth lake and pulled the throttle back immediately, and nobody was hurt.

11-04-2011, 12:36 PM
I'm with vision on this one. Our clubs new LXi had a very distinct whine @ 36 MPH, sounded like the tranny was going to blow. After some changing of parts buy the dealer it was a slightly bent tracking fin.

11-04-2011, 12:51 PM
I should also mention that we did not hit anything and that there was no damage done to anything else, just a clean break and fortunately the blade must have gone straight down to the bottom of the lake.

The vibration is exactly what you feel when power loading, which I have always associated with cavitation.

11-04-2011, 01:12 PM
Things to check/recheck since the vibration is still there with 2 different props:

-prop shaft bent? check with dial indicator
-engine alignment?
-bent strut?

Checking all of the above is all labor time so why not do it?
I would remove the rudder and have it checked to see if it's bent. You may be able to do this with a straight edge or have your MC dealer check it for you.
Borrow a dial indicator and rotate the shaft to see if it has any runout.
Use a feeler guage at the coupling and check to see if the engine is out of alignment.

I would bet at least one of these 3 items is out of spec since you were going 40 when this all happened. If nothing else it will be good to know that these 3 areas are not the problem.

11-04-2011, 01:14 PM
I still say rudder. If there was enough force to break the clevis bolt, I think it could have bent the brass. My guess, like mcantamessa indicated, is that you reach a harmonic frequency at the higher speeds that causes the damaged rudder to vibrate. Probably just a slight distortion.

I do not think it the prop (since it occurs with 2 new props) and if it was the prop design, I would think many others would have experienced this issue. But certainly prop, shaft and strut are possibilities.

I am not sure of an easy way to determine if the rudder is the culprit besides changing it out. I wonder if your dealer would have a spare good rudder you could test?

11-04-2011, 01:18 PM
Borrow another prop, not the same one you're running, to rule that out. I think, like many others, that you have further drivetrain issues.

11-04-2011, 02:01 PM
One more thing ...... (sorry, I am trying to juggle too many issues at once).

I did have a spare 3 blade prop that was originally shipped on the boat from MC and I did place that on the boat and I had no issues. The 3 blade obviously does not create the same effect in the water and it is not the right prop for the way the boat is set-up being that it will allow the boat to run above the safe RPM range.

OK, I think that now covers all of my testing. I know the dealer looked at everything when replacing the clevis bolt but I will ask them to reinspect in the manner that many of you have suggested. This will have to wait until spring as the boat is now tucked away for the winter but it gives me a good starting point for spring.
Thanks for the input.

11-04-2011, 11:51 PM
Unfortunately I've been there and done this, so I have to agree with Dave. More than likely something else like a bent shaft or strut is your problem, but OJ will likely cross ship you another prop to try at no cost of you'd like. Good luck!

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11-05-2011, 07:32 AM
As so many of you have already experienced, Eric at OJ has been fantastic to work with in helping me to figure this out and I can not thank him enough.
Well, based on the feedback I've gotten here, I will have my dealer look at everything in the spring, in terms of shaft, strut and rudder to see what may be out of whack. It is a double edge sword because while I hope they find something, I know that if they do it will have a hefty price tag associated.....gotta pay to play.

Thanks again for the advice and I will update this thread in the spring when I pull the boat back out.

11-05-2011, 08:11 AM
Jeff, unfortantely the boat is probably totaled.....as a friend I would be more than happy to give you scrap value for it.

11-05-2011, 08:40 AM
You are a true friend indeed however, I just would not feel right selling such a problem to a friend, now, maybe if it had a bimini that would be a different story!!!

As a side note, next time you find yourself up this way, let me know, I owe you a few adult beverages!

11-05-2011, 09:51 AM

07-14-2012, 10:55 AM
Jkski .... Thanks to DoubleD I experience the same fate yesterday ...... Hit log at 22 mph ..... Front tracking fin bent ...... Prop bent ...... Shaft looks ok but I will not know until I water test .......... I will hope that my new fin and prop... Take care of it. Tracking fin from MC on the way.

I'll post pics but I wanted to know what your final verdict was on the vibration.

BTW ... Saw the video with you, Boyd, and shredder .... Just wondering why your brother from Columbus was not invited?

Peace .... Be good!

Double D
07-14-2012, 02:53 PM
Now why did I know that was coming?? :) As your lovely wife says, at least I wasn't driving....

Sent from my wife's old iPad using Tapatalk....

07-14-2012, 05:58 PM
Here is the front fin just removed, I think the shaft and strut are in scathed but I really don't know for sure. Took some measurements while turning by hand and it seems ok.81532

I did pull a bit of gel off when the fin came off do I am going to put some repair resin on now while I wait on the fin to arrive on Tuesday


Any ideas are welcome if you think I should take any other steps.

07-14-2012, 06:20 PM

07-14-2012, 06:41 PM
Cloaked .... Thanks ... We are on the same page ... The initial post on this thread was a bit different than mine.

Mine happened yesterday and visually it appears the front fin and prop were the only things damaged ......prop has been replaced and I will replace my fin this week when I get it ..... Hopefully no vibration after I water test .. If so, I will need to really scrutinize the shaft, strut, and rudder.

Fins 2and 3 look good.

Crossed fingers.

Thank you for your support.


07-15-2012, 10:19 AM
See what you guys did? Not a swimsuit pic but Mrs. Prostar is under the boat preparing the area for some small fiberglass repair and preparing for the new fin.


Double D
07-15-2012, 01:17 PM
See what you guys did? Not a swimsuit pic but Mrs. Prostar is under the boat preparing the area for some small fiberglass repair and preparing for the new fin.


Now that's something I'll never see at the Double D house. Good for her!

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