Prop shaft run-out
 

What allowable runout for a standard Bravo prop shaft. Last weekend a submerged log jambed between the prop and cavitation plate. When I put it in reverse it stalled the motor instantly. Found the cavation plate broken. Checked the shaft and have .0035-.004 runout towards the end of the splines. Up close it's out about .002.
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Most say .005 is max, with .0035 or under preferable.

Ayuh,..... At the aft end of the shaft, the threaded end,....

Clean the shaft up and polish it with 220 Emory. And you probably have a run out of .005

Which leads us to the next question; Can it be straightened with a block of wood and a BFH?

No and why? You stated .0035. Spec is .005

Small bottle jack. Keep dial indicator on to measure deflection. Probably not the right fix(replace shaft) but can be done.

This was our test for an insurance claim, was tested on the drive by the adjuster, he showed. 006, within spec, but did the test behind the splines, we pulled it apart, checked it as you see it, claim reversed

If it's out of spec, replace it, no way I would ever try to bend it back, you could damage bearings and a whole lot more trying to safe a few bucks

I would inspect your gears, you may have cracked a tooth. I had a similar situation, except no visible damage until you pulled the prop off. Inspected everything in the water after I felt a thump, no visible damage so I kept boating. Prop shaft and vertical shaft both had a twist in the splines. I found that out after the drive grenaded and I pulled it off to get repaired. Lesson learned, when you feel a thump, pull the prop.

That dial indicator resolution was in tenths of thousandths so...it showed only about .001 runout?

Bajaman,

Nope. The larger graduations are .001". The small graduations between them are .0001". That shaft was showing almost .009" runout at that point on the shaft. Should be considered scrap by nearly anybody's definition.

Thanks. Brad.
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