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Wobble in port shaft

Discussion in 'Post Yacht' started by Stainless45, Jul 16, 2021.

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  1. Stainless45, Jul 19, 2021
    #41
    Stainless45

    Stainless45 Active Member

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    Yeah I'm beginning to see the wisdom in this approach
  2. DOCKMASTER, Jul 19, 2021
    #42
    DOCKMASTER

    DOCKMASTER Senior Member

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    It's unfortunate but you really do need to approach this correctly and do all the appropriate inspections:

    1. Pull BOTH props and shafts - yes from both sides. You don't know what has happened to cause this, better safe than sorry.
    2. Have BOTH shafts checked for straightness AND perform an NDT to ensure no cracks or inclusions
    3. Inspect all cutlass bearings.
    4. Inspect both props
    5. Inspect shaft seals
    6. Have a proper Blue fit check on the props to shafts bore on both sides.
    7. After reinstalling all and the boat has been back in the water for a minimum of 24 hrs, do an alignment check on both sides.
    8. Sea trial

    Of course, in the above steps you need to correct and problems found.
  3. chesapeake46, Jul 19, 2021
    #43
    chesapeake46

    chesapeake46 Senior Member

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    9. keep this thread updated. :)
  4. Capt Ralph, Jul 19, 2021
    #44
    Capt Ralph

    Capt Ralph Senior Member

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    I would also include checking shaft coupler surface with the shafts (repaired or new) while at the shop.
    Ensure the shop marks what coupler goes with its shaft for assembly back on board.

    If your coupler bolts, lock washers & nuts look sad, replace them with fresh grade 8 hardware.

    Great time to ensure shaft log hose and clamps are fresh.
    Install spare seals, if of that type that uses them.

    Dial gauge run out and face distortion on the clutch flange.

    If your going to have it apart, do it all correct and sleep very well.
  5. mapism, Jul 19, 2021
    #45
    mapism

    mapism Senior Member

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    Good point in principle, but just in case the OP is wondering, I'm 99.9% sure that this is not an option with the type of seals he has installed, if you look at his video.
  6. Stainless45, Jul 19, 2021
    #46
    Stainless45

    Stainless45 Active Member

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    I appreciate all the advice. I have a big boat, but not a big boat budget. Not going to touch the starboard as it's giving me no problems currently. Only looking to open cans of worms that I can afford to close, as usual, with a lot of my own labor.

    Will most likely haul the boat Wednesday and see what Johnson Machine has to say about the shaft, assuming I can get the f****r out.

    I will keep the thread updated and post pictures when I get the chance
  7. DOCKMASTER, Jul 19, 2021
    #47
    DOCKMASTER

    DOCKMASTER Senior Member

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    I understand your situation. I would encourage you to wait and see what you find before deciding if you need to touch the stbd side. Hopefully you are good there. But if you find worn bearings or similar you likely would have same on the other side.
    Stainless45 likes this.
  8. DOCKMASTER, Jul 30, 2021
    #48
    DOCKMASTER

    DOCKMASTER Senior Member

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    Any update? Did you haul yet and pull that shaft?
  9. Stainless45, Aug 5, 2021
    #49
    Stainless45

    Stainless45 Active Member

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    Guys sorry for the delayed reply, things have been busy. I hauled the boat and pulled the shaft. Everything went to the machine shop. The shaft is perfectly straight. The coupler has a 2" thick iron spacer ahead of it these were both faced true on the lathe. A new key was made for the coupler bore. We put it all back together. The wobble remains the same. Performed an engine alignment.... The mounts are bedded in an epoxy atop the stringers so unable to be adjusted side-to-side. We were only able to tweak the heights of the 4 corners. Not perfect. The coupler seems to spin true, the wobble is at the shaft. The theory now is that the coupler bore is off-spec, or maybe the key is not seating all the way. I will tear into it agin when she comes out in the fall
    IMG_4697.jpg IMG_4693.jpg IMG_4700.jpg IMG_4701.jpg IMG_4712.jpg
  10. Capt Ralph, Aug 5, 2021
    #50
    Capt Ralph

    Capt Ralph Senior Member

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    I'm confused, was it not assembled in the shop? Surfaced on your shaft? Re-assembled the same way on board? Same shaft key?
    Tapered shaft only goes on one way, unless the shaft ends were reversed...
  11. Stainless45, Aug 5, 2021
    #51
    Stainless45

    Stainless45 Active Member

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    Those are things I need to find out. The shaft did go in exactly as it came out. I was expecting the facing and engine alignment to eliminate the wobble. But when it hadn't she was already back in, of course.
  12. DOCKMASTER, Aug 5, 2021
    #52
    DOCKMASTER

    DOCKMASTER Senior Member

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    Do you have a cutlass bearing in the shaft log or just the one in the strut? What was condition of the bearing(s) ?
  13. Stainless45, Aug 6, 2021
    #53
    Stainless45

    Stainless45 Active Member

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    Cutlass only in the strut, shaft log is a rubber boot with dripless seal. Cutlass was good and had no play.
  14. Capt Ralph, Aug 6, 2021
    #54
    Capt Ralph

    Capt Ralph Senior Member

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    What's up with the spacer? Shaft not long enough?
    I do hate spacers.
    How are you sure the spacer is centered perfectly on the clutch output flange?
    Looks like a big sloppy recess for the clutch flange to center into the spacer.
    How sure are you the shaft coupler is fitting the spacer perfectly?
    I do not see a picture including the male lip on the spacer to center the shaft coupler.

    I'm guessing, the clutch flange did not go to the machine shop or did it?

    Clutch flanges are easily damaged during clutch R&R from / to the boat.
    Amazing nobody ever checks them after the smallest strike.
    Or, the flanges are bent using it as a press back when trying to pop out the shaft from the coupler.

    Sorry I did not think about this during your thread.
    Last edited: Aug 6, 2021
  15. Stainless45, Aug 6, 2021
    #55
    Stainless45

    Stainless45 Active Member

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    The coupler and the spacer have a centering lip and recessed edge so it all goes together with no play. The clutch flange was not removed. The machine shop asked if the boat had been repowered due to the spacer. I know the 692's and gears were replaced with 692's and gears, but I don't know if the gears are the same model. These are Twin Disc 509's
    The coupler and spacer seem to spin true, the shaft is where the wobbling begins
  16. DOCKMASTER, Aug 8, 2021
    #56
    DOCKMASTER

    DOCKMASTER Senior Member

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    Make sure you keep a close eye on that shaft seal until you get this figured out. Running it with that wobble is surely putting more stress on that seal.
  17. Stainless45, Aug 8, 2021
    #57
    Stainless45

    Stainless45 Active Member

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    Agreed. I'm working on a theory that maybe the key between shaft and coupler is not sized right. preventing the shaft from centering itself fully in the coupler. Just a theory, I won't be able to do anything on it for another week.
  18. DOCKMASTER, Aug 8, 2021
    #58
    DOCKMASTER

    DOCKMASTER Senior Member

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    So your thought is the key is too tall and thus forcing the shaft against the other side too much? Anything is possible. But if it was the key wouldn’t you have always had this issue then? Either way though, easy enough to verify your thoughts with a blue fit. You can do one without the key first to verify the fit then again with the key to ensure the key is not altering your contact area.
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  19. T.T., Aug 8, 2021
    #59
    T.T.

    T.T. Senior Member

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    Double check that strut also..I've witnessed a persistent wobble that was finally solved by remounting the strut and the strut showed no exterior evidence to suspect. Everything else was replaced with new.
  20. Capt Ralph, Aug 8, 2021
    #60
    Capt Ralph

    Capt Ralph Senior Member

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    Should be the same key as when the coupler was surfaced.
    Could be just assembled wrong or differently than the machine shop.
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