vibrations

I have an 89 2001 Ski Nautique. It shakes/vibrates occasionally when I put it in reverse. It also does it when I first put it in gear going forward - engine is definitely not warmed up yet when it happens. It does it a couple of times at first going forward then is smooth for the rest of the outing. But in reverse it happens periodically throughout the outing.   I do have some nicks on my prop but I would think it would cause vibrations all the time if that was causing it.

Is the prop tight on the shaft? Mine was loose & let me know it in reverse!

8122pbrainard wrote: How many hours and has the damper ever be changed?

I can tell someone has been inside the tranny before - maybe during engine swap/rebuild but don't know anything else about it.

what is engine speed when you first engage fwd or reverse?? if it's pretty low (<500 RPM) that can cause some vibration.

MI-nick wrote: what is engine speed when you first engage fwd or reverse?? if it's pretty low (<500 RPM) that can cause some vibration.

Engine speed is usually pretty low when it vibrates but not always. Not sure on the RPMs though. I'll pay attention to that next time I go out.

That prop needs to GO! Can't be good for the drivetrain running that thing can it?

You have a bad cutlas bearing in the strut if you have the 1/64" to 1/32" wiggle. With the bad prop, I'm sure you are getting shaft vibration.

Shaft out, yes. Rudder out, no.

teelta wrote: I got an estimate of $125 to repair prop with a 3-4 day turn around. Is that reasonable?

Yes that sounds like the going price. Typically they will want to inspect the prop and confirm the price. If the damage is real bad but still reparable, then the cost may go up.

I got an estimate on replacing cutlass bearing. Mechanic said he would take off the strut rather than take out the shaft. That sounds a little easier to me as long as the strut gets lined back up right. Is this an acceptable way to replace the cutlass bearing? or just a lazy mechanic? :) How hard is it to get the strut lined back up?

Trey,
Ether method is fine and each has it's pros and cons. Getting the shaft out can be a PITA but you don't loose the strut alignment. Taking the strut off you can loose the alignment. When he puts the strut back on, he should unbolt the coupling halves and make sure the shaft is happy (turns freely) when the strut is tightened up. He may find shims under the strut and those should go back in. While he's into it, I highly recommend he checks the shaft to engine alignment.

WHY are you not doing this yourself????

BTW, remove your double post.

Actually I think I understand the process pretty well. What I need more is...what do I need to replace or consider while in the process (i.e, upgrades, shaft seal, etc)...still intimidated by the shaft/ strut alignment :)

Trey,
Even with a bad cutlass, you should be able to get a good idea if there is a shaft problem just by holding the shaft to one side of the cutlass bearing.

That collar is the safety collar. It's there so if you break the shaft or it comes out of the coupling you won't loose the shaft plus the prop won't hit the rudder.

Yes, the fins can be straightened. The best way is off the boat in a press but I do know some have straightened them on the boat.

Trey,
That key should be all the way in the shaft keyway but worse, it looks like you are losing the shaft in the coupling. It was ether not installed properly or due to bad alignment the shaft and coupling have fretted. Was there a black smut around the interface btween the coupling and the shaft? It's a good indicator of fretting. That coupling fit to the shaft is critical. It's a heat shrink .000" to -.0005" fit. I suggest removing the coupling and getting some measurements on the shaft OD and coupling bore. You may need a new coupling and have it bored to match the shaft. The straightness of the shaft needs to be checked as well. It should not run out more than .003". Check at the prop taper too especially since the prop is bad.

When you opened up the coupling, did you take the feeler gauges out and check the alignment?

Some heat may be needed and wouldn't hurt on the cast brass but it's not always needed. Think about it this way - they bent when they were in cold water!

Trey,
Sorry but the picture must be deceptive since it does look like the shaft has slid aft in the coupling. The shaft only needs to be flush with the inside face of the coupling.
Some have had good luck with shaft straightening others have not. There are times when the shaft wants to go back to the bent position.
If you do go new, I highly recommend the ARE double taper system. The taper at the couplng makes R&Ring the shaft easy. No heat shrink which can be a PITA.