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prop shaft bend
https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=10088		 Page 1 of 1
Author:  jontmiller [ Mon Aug 13, 2012 8:32 pm ]
Post subject:  prop shaft bend
Hello from CT,

Just purchased a used 1998 Horizon H200 with Volvo Penta 4.3 GL. While I am sure there are plenty of things this new to boating rookie missed on the inspection, while cleaning it up I noticed a slight wobble while spinning the prop.

No obvious prop damage which leads me to believe it has been this way a while. Didnt notice anything while on the test ride but as a novice don't know what it would feel like.

I am ordering the manual, and was planning on fixing it when I winterize the boat in a few more weeks. Curious how big a deal this is, can it wait? My feeling is there are probably quite a few boats running around out there with bent shafts that are not aware of it,

other suggestions welcome, boat cleans up nicely, hoping there arent too many hidden things but assuming on a 14 year old boat there will be some. enjoying the forum, just which the search function was a bit more robust.


gratuitious crappy cell phone photo

Image
Untitled by millerjont, on Flickr
Author:  fiznuka [ Mon Aug 13, 2012 8:46 pm ]
Post subject:  Re: prop shaft bend
Do you have a spare prop to spin and make sure it's not the prop hub? As to running it with a bent shaft I would not recommend it that little vibration will work its way up the chain (bearings in the drive, u-joints, gimble bearing, engine drive coupler etc.) A little time spent now to repair will save you alot latter. I'm sure the rest will agree
Author:  NiagaraChillin [ Mon Aug 13, 2012 8:55 pm ]
Post subject:  Re: prop shaft bend
fiznuka wrote:
Do you have a spare prop to spin and make sure it's not the prop hub?


Also, check to see if the prop is secured to the shaft tightly, ie loose nut. Start small and easy with your checks, sometimes the simpliest things are what causes the most problems. Like fiznuka said, getting on top of this now could save you $$$ down the road.

And welcome!
Author:  Steve K [ Wed Aug 15, 2012 6:16 am ]
Post subject:  Re: prop shaft bend
I would take the prop off and get a dial caliper, set it up directly to the shaft, and the spin the shaft by hand. This will tell you if it is bent.
Author:  jontmiller [ Fri Aug 24, 2012 8:36 pm ]
Post subject:  Re: prop shaft bend
back from vacation, pulled prop today and shaft definately bent.

How big a job? ballpark cost to have a shop do it? How easy a DIY (book on order)

My feeling is still that it has been like this for awhile (asked previous owner...while he could be lying he seems genuinly surprised and wasn't aware)

was leaning towards not doing anything short term, figuring any damage is already done.

Thoughts, suggestions, previous experience?
Author:  Steve K [ Fri Aug 24, 2012 9:21 pm ]
Post subject:  Re: prop shaft bend
If it is bent and you continue to use it you may be damaging other items like bearings, etc.. I looked at my book and it is a job I would tackle myself.
Author:  boater [ Sat Aug 25, 2012 7:18 am ]
Post subject:  Re: prop shaft bend
I wouldn't drive it around like that.
I had mine straightened about 7 years ago and haven't had a problem.
If you find the right shop, I'm sure it's cheaper than replacing it.
Author:  Borchik [ Mon Aug 27, 2012 6:44 am ]
Post subject:  Re: prop shaft bend
There is an "easy" way to fix bent shaft in certain situations. If there is no moisture in the gear lube then the bend is on the outside of the seal of the gearcase. Believe it or not this can be straigtened in about 5 minutes using a bottle jack. I have done it a few times and have seen it done dozens of times and never had any long term issues. V/P's are the best drives to handle this because they have the toughest gearsets. The quick instructions are basically using the bottle jack between the prop shaft and cavitation plate and pushing the shaft straight. You use a piece of wood between the shaft and plate and actually put the jack against the prop nut on the shaft. You actually bend the shaft in the opposite direction, release the jack, check it and do it again until straight. It takes a few tries even for the most skilled of hands to get it perfect but it can be done. Shops use this all over but keep it quiet because of how much more labor they can get if the drive gets torn right down. A machine shop straightens the shaft in basically the exact same way, just using a much bigger machine.

All that being said if you are not mechanically skilled at all I would not recommend attempting this because there is the possibility to do far more damage then you already have!
Author:  Cap'n Morgan [ Mon Aug 27, 2012 7:06 am ]
Post subject:  Re: prop shaft bend
jontmiller wrote:

My feeling is still that it has been like this for awhile (asked previous owner...while he could be lying he seems genuinly surprised and wasn't aware)

was leaning towards not doing anything short term, figuring any damage is already done.


If your feelings are true, good chance there is more damage internally. If you continue to run it this way, you will not be happy with the cost of getting towed back in, and the repair bill. Stop running the boat, get it looked at and fixed before you use the boat again. :!:
Author:  LouC [ Mon Aug 27, 2012 8:38 am ]
Post subject:  Re: prop shaft bend
Wow Brian that is interesting, I would not have thought you could do it that way, but those jacks can apply a lot of pressure, like a hydraulic press in a smaller package....
If you kept checking it with your dial indicator, you probably could get it pretty close...
But as Captn said, there is also the possibility of fractured gears that will eventually let a tooth loose and damage the drive....
Author:  Borchik [ Mon Aug 27, 2012 10:04 am ]
Post subject:  Re: prop shaft bend
It works, I know a guy who gets them dead on every time doing it that way. If you think about how a shaft gets bent, the bend will 99.9% of the time be just between the prop and the carrier, and when you use the jack it will bend it in exactly the same place. Extremely rare to get a fractured gear on a VP, at least in comparison to an Alpha. I have actually seen a prop shaft break clean off a VP and not a gear in the thing had a mark on it, that was about 5 years ago. The guy put a prop shaft in it and has been running it ever since with not an issue.
Author:  jontmiller [ Mon Aug 27, 2012 2:05 pm ]
Post subject:  Re: prop shaft bend
So this sounds interesting,

I have a friend with full access to a machine shop with pros that can probably straighten it if I take it apart for them, but this bottle jack method intruiges me. I have seen some photos of a kit designed to be sold to mechanics...are there any photos of this ? it sounds right up my alley (cheap and rather Rube-Goldberg esk)
Author:  Borchik [ Mon Aug 27, 2012 5:44 pm ]
Post subject:  Re: prop shaft bend
I do not have any and I did a quick youtube search but did not find anything quickly...
Author:  jontmiller [ Sat Sep 01, 2012 11:55 am ]
Post subject:  Re: prop shaft bend
Well, threw caution to the wind and gave it a go with a bottle jack.

Before I started I checked the gear oil and it was clean with no signs of H20, too bad I didnt take a before video because while its not perfect, its 90 percent better than it was, and I think with a bit more time to play with it (have to work today) I really could have gotten it right on.


Image
Untitled by millerjont, on Flickr


sorry for the poor photo, I really didnt think it was gonna work so I didnt document it as good as I should have, will check the gear oil again after getting it into the water just to make sure, but I am assuming its going to be just fine.

I wouldnt have pulled this on a new boat, but 14 years old and assume a history of this bend being there for awhile I though I didnt have much to lose, if I see water in the oil in the future I will pull the shaft and have it professionally straightened.
Author:  Borchik [ Sat Sep 01, 2012 5:32 pm ]
Post subject:  Re: prop shaft bend
Nice, one suggestion if you try to do it some more. Put the prop nut back on, threaded until the nut is flush with the end of the shaft, put the jack on the nut and then put a 2x4 across the top or a slice of plywood to spread the pressure out better. Otherwise you got it.
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