2002 super air vibration

[mike32]

Anyone have any ideas? beloww 35mph boat is smooth as silk. Above 35 has a vibration that is pretty strong and increases as speed does. shaft bearing?

[Chexi]

Any dings in the prop?

[mike32]

Any dings in the prop?

it look great, is that the first thing I should start with? With a dial indicator is there an allowable tolerance for the cutlas bearing? or am I way off here?

[mastercard]

You are headed in the right direction with the dial indicator. Check your prop shaft run out then check alignment. There is a video somewhere, maybe on www.correctcraftfan.com detailing the process.

[mastercard]

http://www.planetnautique.com/vb3/sh...otor-alignment

[crobi2]

2002 is getting a little long in the tooth for a cutlass bearing if you have been running in any silt. Check it by grabbing the prop/shaft and yanking up and down to see how much play there is in the cutlass. A new one has no movement at all. Anything more than about 1/32 (.031) of play is too worn. So if you yank it and it goes thunk in the strut, it it probably worn.

The biggest thing though is to check the shaft bend. You can use a dial indicator to check shaft runout. Unfortunately, you will probably have to pull the prop to check the runout past the strut.

You should probably also check your alignment (very painful to do under the v-drive!).

[mike32]

It looks like the strut bearing does have some play I didnt put the dial indicator on it because it was enough that I could see. I checked the prop and it looks perfect. The strut has some play but it doesnt have enough that it makes any noise. Would this be enough to cause the vibration? How do I get it out? Do I need any special tools? thanks in advance.

[mastercard]

Mike, I have yet to replace a cutlass bearing but my thoughts on doing it would involve machining a sleeve to replicate the bearing itself, only slightly smaller in OD, and halving it so that it would fit around the shaft and using it, along with threaded rod to press the bearing out without removing anything but the prop, but, I like to make stuff and have the means to do so. I think others have used a hacksaw to cut the bearing lengthwise, from the inside and use whatever tool might be available to dig, pull, pry or scrape it out.

Do check the runout on the shaft to make sure it is straight, no more than .003. Rotating the shaft by hand with a worn bearing will give you some wacky readings on the indicator. Take a piece of rope and tie your shaft to the prop cage on your trailer, creating some pressure that will help to minimize the slop while you rotate the shaft.

BTW, At one time I had a prop that appeared to be perfect but was creating a noticeable vibration, I swaped it out with another that was new and the vibration went away. I sent the old one off to get checked out and indeed it had a bent blade. It doesn't take much to throw a prop out of whack and can be hard to see.

Is the boat in question new to you?

[mike32]

I will send it off, hopefully it doesnt take long to get back.

[shag]

I would bet it is your prop. Same here, one time I had a higher speed vibration. The prop looked perfect. I sent it to a prop shop to have reconditioned..... No more vibration. Must have been off just enough...

[mike32]

New prop on, good to go! I swear the old old looks good but I will have it checked out.