Prop strike, vibration

[Hrkdrivr]

Kind of a before and after set. The rope, before the prop shaft ate it, and the rope after it was liquified and burned its way forward through the bearing, collecting and hardening on the front of the bearing inside the strut bushing.

I'm ashamed to show these photos, but if just one person learns from my mistake...

[TOO-TALL]

Good job.Thanks for the pics.

Maybe the vibration was caused by the bad cutless bearing? combined with the bend prop.

Also I would lightly sand rust and corrosion off the face of the shaft coupler and the tranny coupler were they met.This way you can get a good feel with the feeler gauge when setting the .003.

[FrankSchwab]

Wow, great write-up but a bummer of a problem.

BOAT - Break out another thousand.

Have you been able to verify that the strut isn't bent? (I know, I know, just another thing to replace...). It's an easy check - put the cutlass bearings back in just a little bit (to center the propshaft), slide the propshaft through and see if it goes more-or-less through the middle of the shaft log. As a practical matter, as long as it doesn't strike the sides, it's good enough.

It's easy to have a slightly bent strut that points the propshaft to the side of the shaft log; the propshaft will bend enough to go through, and you can even do the factory propshaft alignment (the 0.003" side-to-side variance on the coupler) with the shaft bent that way - but it won't be a smooth running boat.

If the strut is OK, I'd suggest following the attached procedure to align the engine to the propshaft. It made a small but noticeable difference in smoothness on my boat.

PROPSHAFT_ALIGNMENT-15676.doc

/frank

p.s. By the way, my understanding is that you should have been able to get the propshaft out without removing the rudder. It's offset slightly to the side of the prop, and the shaft is supposed to be able to slide out right alongside it. I've never removed mine, so I don't guarantee that is true...

[mtajpa]

Thanks for sharing your troubles. I sure we will all benefit from your experience.

[sand2snow22]

Well done, did you roll the shaft on a smooth floor to see if it was bent? I had a local shop straighten mine. It was bad, but he got it back to .003 without using heat! Going to test it in another boat...

[Hrkdrivr]

Originally Posted by TOO-TALL

Good job.Thanks for the pics.

Maybe the vibration was caused by the bad cutless bearing? combined with the bend prop.

Also I would lightly sand rust and corrosion off the face of the shaft coupler and the tranny coupler were they met.This way you can get a good feel with the feeler gauge when setting the .003.

I think it was a combination of the prop, bearings and shaft. I'm replacing all three since OJ said the prop was bent/unrepairable and the bearings were smoked. Hopefully this will take care of it!

Thanks for the advice on the sanding. I will do that to the face to the tranny flange. The new shaft comes with a new coupler.

[Hrkdrivr]

Originally Posted by FrankSchwab

Wow, great write-up but a bummer of a problem.

BOAT - Break out another thousand.

Have you been able to verify that the strut isn't bent? (I know, I know, just another thing to replace...)...

If the strut is OK, I'd suggest following the attached procedure to align the engine to the propshaft. It made a small but noticeable difference in smoothness on my boat.

/frank

p.s. By the way, my understanding is that you should have been able to get the propshaft out without removing the rudder. It's offset slightly to the side of the prop, and the shaft is supposed to be able to slide out right alongside it.

Thousand...yes! Prop, shaft, bearings...right around a grand. Ugh

As for the strut, ugh. It didn't look bent but I will check it when the new shaft gets in.

Thanks for the alingment procedure. I'll take a look and see if it's something I can pull off.

I too have heard/read the shaft should clear the rudder, but it just wouldn't happen no matter where I placed the rudder. The aft end of the shaft wouldn't go any further aft than about mid-chord on the rudder. Maybe that's because it was bent?

[Hrkdrivr]

Originally Posted by sand2snow22

Well done, did you roll the shaft on a smooth floor to see if it was bent? I had a local shop straighten mine. It was bad, but he got it back to .003 without using heat! Going to test it in another boat...

I haven't rolled it on the floor yet, though the dial gauge said it was bent. I'm going to find a shop to see if they can straighten the old one for a spare. It's sure an expensive piece of steel to waste.

[EJ OJPROP]

Chad - Shaft and bearings are shipping out today.

[CCAnderson]

Originally Posted by Hrkdrivr

Here are some shots of the shaft and coupler after I got them out. What I realize now (plus Eric told me) is that the shaft must be seated all the way into the coupler. When you put the nylock nut on, I could only see maybe one thread's worth of shaft protruding forward. I guess if the nylon part of the nut is filled totally with threads you don't need much more. It'll take a good bit of torque to get the nut on that far.

A splined shaft should not take a ton of torque to seat the coupler or prop as both should slide right onto the shaft with a bit of lubricant. Corrosion was the cause of the prop and shaft being difficult to remove. As far as one thread showing on the nut, that is OK. the top rounded part of the nyloc nut is not load bearing it serves only keeps the nut from loosening over time. as long as you have full thread engagement and the shaft are seated properly you are good to go.