Inboard Straight Drives - stiff prop shaft

[rlynch03]

At what point is your prop shaft to stiff? My starboard side is so tight I can barely turn the prop (while on the hard) by hand. The port side prop shaft is pretty easy to turn but nothing like an outboard for example.

I have a mechanic coming to look this week but wanted some of your input before hand.

For reference I have 07- QSM11’s w/ ZF 325 transmissions.

I suspect an my Cutlass Bearing is part of the problem or maybe I need an alignment.

Is the best process to replace Cutlass Bearings and then do an alignment in the water? My mechanic said the alignment needs to be done with a special laser tool also.

Thanks for any real life feedback. A couple pictures are included of the back side of my cutlass bearing that I think looks a little jammed up.

 

[PlayDate]

You are on the right track. You should generally have the same resistance on both props. The culprits (in order) are alignment, cutlass bearings, bent strut or shaft. Any prop strikes last year?

 

[rlynch03]

You are on the right track. You should generally have the same resistance on both props. The culprits (in order) are alignment, cutlass bearings, bent strut or shaft. Any prop strikes last year?

John- thanks... No prop strikes at all. The starboard prop shaft has bee stiff since I purchased the boat 2.5 years ago. My mechanic adjusted the motors mounts stating that loosened up the shaft. He didn't think the issue was the cutlass bearing. It spins inside the engine room smooth without wobble that I can detect with my eye. Both motors get to 2350 rpms and both are pretty close to the same fuel burn.

Did you think the back side of that bearing looks off or worn?

 

[Woody]

John- thanks... No prop strikes at all. The starboard prop shaft has bee stiff since I purchased the boat 2.5 years ago. My mechanic adjusted the motors mounts stating that loosened up the shaft. He didn't think the issue was the cutlass bearing. It spins inside the engine room smooth without wobble that I can detect with my eye. Both motors get to 2350 rpms and both are pretty close to the same fuel burn.

Did you think the back side of that bearing looks off or worn?

That cutlass brg is shot. I'd change both brgs first and re-assess before anything else.

 

[techmitch]

That cutlass brg is shot. I'd change both brgs first and re-assess before anything else.

Yea, sure does look that way and no laser needed for alignment.
http://www.marinegears.com/pdf/GetInLine.pdf

 

[rlynch03]

That cutlass brg is shot. I'd change both brgs first and re-assess before anything else.

Thanks Woody. For my education can you please tell me what they tell tale sign was?

 

[Woody]

Thanks Woody. For my education can you please tell me what they tell tale sign was?

The easiest is that the rubber is separated from the outer bronze tube of the brg unit. The rubber is cracked in the lands of the brg and you can see the edges overlap each other. There is also mineral buildup or mud or something in between the rubber and the bronze that it is normally bonded to.

This is what it should look like, even with normal wear on it the clearance would increase between rubber and shaft but you'd still recognize it.

 

[my3sons]

FWIW, I agree they are shot. Here's a before and after of when I did mine a few years ago.
Mine didn't look near as bad in the boat, but once they were out, it was obvious they were shot.

When there is an alignment issue, balance problem or bent shaft, the bearings will wear prematurely. If everything is ok, they eventually will wear out, but sometimes just dry rot and fall apart first, that appears to me what has happened to yours, but of course no way of knowing for sure. Do the bearings first, they definitely need it, then check alignment if you still suspect an issue, however, keep in mind that when on the hard, the way the boat is blocked can make a difference in alignment. Boats are just big pieces of plastic that flex and twist when blocked, especially ones stored outside on the ground, and blocking may settle differentially over the winter. They are meant to be supported by water on every square inch of the bottom.

 

[ttmott]

I'm going through exactly this right now. Hard to turn even from the propellers. You should be able to turn the shafts by hand from the couplings. Yesterday I removed the coupling bolts and a significant gap opened up on one side; not a good sign. This morning we pulled the shafts back and the coupling sprung to one side which is indicative to a bent strut.
Once the couplings were separated the shaft turns freely. So, I would pull the bolts out of the couplings and look to see if a gap opens up somewhere around the coupling. Then pull the shaft back a bit and see if the couplings remain aligned somewhat. Pictures later today.

 

[Strecker25]

I also recently dealt with a similar issue. Turned out my strut was bent, so I had it straightened and realigned the entire driveline. My tell tale sign was when I pushed the cutlass out of the strut using a strutpro tool the shaft snapped against the inboard side of the now empty strut opening. Once I got the strut off the boat it was clear as day I had a 1"+ bend.

I'd replace the bearing and check alignment before going too much deeper. Final alignment will be done in the water but you can get it close on the hard. You should also pour some water through the cutlass on the hard when you try to rotate it, when they sit dry they're tough to get started and can give the illusion of an issue.

You can also detach the shaft coupler from the transmission and rotate each independently to see where the bind is. If both rotate easy when de-coupled it could be as simple as a re-alignment to reduce the resistance.

 

[Blueone]

I was at the boat today and thought I would send you a pic of a good cutlass.... turns out mine don’t look so great. Got a few cracks and a bit of clearance issue... Thanks for that

 

[Sidewinder770]

Just went through this myself. Same thing happened- removed bearing and shaft moved to the outside of the strut. Turned out to be a bent strut but it was so minimal you could barely see it- maybe 1/2" but that makes a big difference over the length of the shaft. Even with the shaft pulled out it's hard to see a bent shaft unless it's really bad. If it is a bent strut send the shaft with it to get checked out.

 

[Strecker25]

here’s how it should NOT look

and how it should. Pretty dramatic side by side

 

[Soulshine]

Assuming that you have pocket drives, how was the room between the back of the strut and the hull?

I have straight drives and there’s not a lot of exposed shaft to hang the tool on.

Of course I noticed after purchasing the Strut Pro.

 

[Strecker25]

Assuming that you have pocket drives, how was the room between the back of the strut and the hull?

I have straight drives and there’s not a lot of exposed shaft to hang the tool on.

Of course I noticed after purchasing the Strut Pro.

I had no issue with clearance but I went from the bottom (openings facing up) then put the plates from the top side so the tool was hanging from the shaft.
Our shaft exits the boat pretty far forward so there’s a lot exposed underneath leaving lots of room to attach the tool

Best 400 spent in a while, makes the job easy

 

[Soulshine]

Yep. I just caught myself not realizing that the entire tool doesn’t go behind the strut.

My shafts are super short in general though. Good news if needing replacement.

You have V drives I’m guessing?

 

[Strecker25]

Yep. I just caught myself not realizing that the entire tool doesn’t go behind the strut.

My shafts are super short in general though. Good news if needing replacement.

You have V drives I’m guessing?

we do, I believe the shaft is around 6-7’ long and I’d guess at least 4 1/2’ of that are outside the boat

 

[Soulshine]

You know with us being so near each other I wish you’d have known that I had the tool.

You would have been welcome to borrow it and it would’ve been good to meet.

Anyway...hijack complete.

 

[Strecker25]

You know with us being so near each other I wish you’d have known that I had the tool.

You would have been welcome to borrow it and it would’ve been good to meet.

Anyway...hijack complete.

i was thinking the same thing, always happy to lend out specialty stuff where needed!

 

[firecadet613]

Glad you guys were able to get it to work. Tried StrutPro, no go. Marina tried their contraption to get it out, no go.

They ended up pulling the strut and using a press to get it out.