Prop shaft seal ID

Engines, Drive trains, Propellers, Steering, Ground Tackle and other mechanical system
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Pelican
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Joined: Fri Dec 18, 2020 8:59 am

Prop shaft seal ID

Post by Pelican »

We have a 1981 Freedom 40 center cockpit, built in the UK and need to ID the type of prop shaft and seal used. Anyone have any idea? The mechanic in Oriental, NC, says it might not be marine specific and could be a tractor part. We have a seized prop shaft and it looks to be the prop shaft seal has grabbed ahold of the shaft, spun and stuck. Now trying to see if the seal can be replaced or if we need a whole new shaft assembly. He’s never seen this type of prop shaft seal before.

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RadioZephyr
Posts: 161
Joined: Mon Jun 27, 2016 10:04 am
Location: Boston, MA

Re: Prop shaft seal ID

Post by RadioZephyr »

I know that the earliest Gary Mull-designed Freedoms used a Syntron shaft seal, which was indeed an industrial part, not a marine-specific design. It looks like this:
Syntron.jpg
Syntron.jpg (55.71 KiB) Viewed 170 times
The problem with the Syntron seals is that over time the two lip seals inside wear grooves into the prop shaft. If that's what you have, you should definitely not replace it with another Syntron. I'm not sure what the stern tube of a F40 looks like, but the only dripless seal that will fit in the later boats is made by Tides Marine. They specially modify their seriesOne shaft seal so that it's short enough to fit in the tight space behind the engine.
Josh
Sunset Spy
F38, Hull #152
Boston, MA

Pelican
Posts: 4
Joined: Fri Dec 18, 2020 8:59 am

Re: Prop shaft seal ID

Post by Pelican »

Thanks, Josh. I think that’s it. Sounds like the yard is going to rebuild the whole prop shaft to simplify it. Will probably take a couple of weeks. Not how we envisioned our cruise back to the Chesapeake going!

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RadioZephyr
Posts: 161
Joined: Mon Jun 27, 2016 10:04 am
Location: Boston, MA

Re: Prop shaft seal ID

Post by RadioZephyr »

Oof, yeah, that's a tough break. At least it's one less thing to worry about going forward! Hopefully it'll also work in reverse.
Josh
Sunset Spy
F38, Hull #152
Boston, MA

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