My shaft wobbles - how do I measure it?

PiratePast40

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Outdrive is a Volvo 280. The prop seemed to wobble with a new prop but not as bad as the older one. Wondering if it's the prop or the shaft itself. There is a noise in the lower end when I turn the shaft by hand. No grinding or scraping noise but not the smooth sound you would expect. There is no visable play or movement in the shaft when I try to wiggle it by hand.

I'm guessing that it could be a bearing or a bent shaft and want to be proactive. To check for a bent shaft am assuming I'll need to use a dial indicator to measure runout, does anyone know the spec on this?

I did pick up a spare lower gear and bearing assembly of the proper ratio with a matching drive gear on ebay for $25 just in case.

Any other ideas?

Thanks
 

PiratePast40

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Re: My shaft wobbles - how do I measure it?

Thanks Don,
I've got the manual and have gone through it page by page but haven't been able to find the runout measuring procedure or spec. I can figure out how to do it, just not sure what's acceptable.
 

Don S

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Re: My shaft wobbles - how do I measure it?

It may have been in a training manual I had (I don't have it any longer) The spec usually involved taking the shaft out of the drive, using V blocks and checking the middle of the shaft. Only had something like .003" allowed. Very little.
 

PiratePast40

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Re: My shaft wobbles - how do I measure it?

Maybe I'm worrying about something that's a non-issue. I'll just keep an eye on it. I've learned (the hard way) not to take things apart when it's not needed.
 

picklenjim

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Re: My shaft wobbles - how do I measure it?

Not sure about on a Volvo but I can tell you on a Merc the max runout is .005". Max movement side to side is .003". You would think something like that would be pretty much about the same.
 

Bondo

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Re: My shaft wobbles - how do I measure it?

Not sure about on a Volvo but I can tell you on a Merc the max runout is .005". Max movement side to side is .003". You would think something like that would be pretty much about the same.

Ayuh,... My personal rule of thumb in general Mechanicin' is,...
If you can SEE it wobble,...
It needs tendin' too....
 

PiratePast40

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Re: My shaft wobbles - how do I measure it?

^^^^^ I can see the wobble when it's running with the prop on but have heard that props aren't necessarily perfect. When on the water, there is an area around 3500 - 3800 rpm where there is some vibration. But thats also the rpm when it's coming off of plane or too slow to get on plane so don't know if that's a good indicator. Moving the throttle one way or the other moves out of that harmonic range.

I'll go ahead and borrow a dial indicator setup so I can get something tangible.
 

Don S

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Re: My shaft wobbles - how do I measure it?

I can see the wobble when it's running with the prop on but have heard that props aren't necessarily perfect.

Take the prop off and run it. Props always wobble.
 
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