Possible inboard porp shaft movement

[homelite]

On my 1999 Sea Ray 310 Sundancer with V drives, on the starboard prop shaft, behind the cutless bearing, I see a shiney polished ring as if the thrust of pushing forward is moving the shaft forward roughly 1/4". The port shaft does not show this. I have no vibrations or issues, but it puzzles me. As hard as I can push/pull on the prop i get no movement in the shaft. Does the/can the engine and trans move that much under load yet stay "straight" as to not "****" at all and cause a noticable vibration?

I'm just wondering from someone that works on these all the time. I am a mechanic, but do not work on inboards for a living.

I looked around the boatyard at others. Some show this type of "wear spot" and some don't.

Made me curious in case there is something I need to be looking into!

 

[alldodge]

On my 1999 Sea Ray 310 Sundancer with V drives, on the starboard prop shaft, behind the cutless bearing, I see a shiney polished ring as if the thrust of pushing forward is moving the shaft forward roughly 1/4". The port shaft does not show this. I have no vibrations or issues, but it puzzles me. As hard as I can push/pull on the prop i get no movement in the shaft. Does the/can the engine and trans move that much under load yet stay "straight" as to not "****" at all and cause a noticable vibration?

I'm just wondering from someone that works on these all the time. I am a mechanic, but do not work on inboards for a living.

I looked around the boatyard at others. Some show this type of "wear spot" and some don't.

Made me curious in case there is something I need to be looking into!

Have you checked the shaft coupler? If you have the type which goes through the transmission and attaches on the back side, the nut could be wearing.

 

[kmarine]

What type of shaft seals do you have I have pss shaft seals and ended up having to replace my bellows as the main bearing in my starboard v drive had a worn bearing and I ended up with a wet shaft seal(with trans fluid) on the drive which needed replacing. Keep in mind the shaft pushes against the v drive to propel the boat. It cost me about $1000 to rebuild the v drive and replace the shaft bellows. I would check the couplers and seals and make sure everything is tight in the engine room.

 

[homelite]

To address both replies. I have the tapered shafts on both ends, with the large nut in front of the v drive. It's tight and fine. I'm lost on the prop shaft seal question because that has nothing to do with it. To answer though, I installed the lastdrop seals a few years ago and they are perfect.

If I had play in the trans, you'd think I'd notice it by pushing and pulling on the prop. There is none. I guess once launched again in March, I'll have someone else drive and accelerate while I look and measure if the thrust actually does push it forward 1/4" Like I said, looking around the boat yard at others, some show the same thing. Maybe the mounts are designed for a little forward thrust movement, instead of a twist motion like cars and trucks do? I get no vibration so probably there is nothing wrong. It just puzzled me.

Thanks,

 

[alldodge]

To address both replies. I have the tapered shafts on both ends, with the large nut in front of the v drive. It's tight and fine. I'm lost on the prop shaft seal question because that has nothing to do with it. To answer though, I installed the lastdrop seals a few years ago and they are perfect.

If I had play in the trans, you'd think I'd notice it by pushing and pulling on the prop. There is none. I guess once launched again in March, I'll have someone else drive and accelerate while I look and measure if the thrust actually does push it forward 1/4" Like I said, looking around the boat yard at others, some show the same thing. Maybe the mounts are designed for a little forward thrust movement, instead of a twist motion like cars and trucks do? I get no vibration so probably there is nothing wrong. It just puzzled me.

Thanks,

Just finished working on one of those last fall. The shaft goes through the transmission and comes out the other side, then there is the coupling cone and a large nut on the end with a carter pin. This one was moving also but didn't know it at the time. When the boat was in forward the shaft was pushed and then we could see a gap under the nut. After removing the nut we found someone had ground down the back side of the nut to get the carter pin in. Turns out they were using the wrong key so it slide back and gave it slop.

You could check by removing the nut and see if there is any play in the shaft found. Could also use the time to check the .003 clearance when loosening the outer four bolts

 

[Bt Doctur]

A typical install is a square keyway about a 2 inches long between the shaft and shaft coupling, then 2 locking screws that fit into 2 indents/recesses of the shaft
a safety wire securing the 2 lock bolts.

 

[Bt Doctur]

check the locking bolts to see if it is still in the 2 recesses/detents of the shaft

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