Low speed vibration

Seen a few posts similar, but all tend towards vibartion and noise at speed, so sorry if duplication...

Alpha 1 Gen 2 - 210 hours.

Has been fine recently, but out a few days ago and whilst pulling away in marina noticed vibration/shimmy through wheel and could see screen moving in front of me at very low speed. No unusual noise. On the plane no obvoius problem, no noise on turning or vibration on turning that i noticed.
At home, out of the water, spinning prop by hand with drive down produces a small but palpabale "shimmy" of the drive and the center hole of the prop shaft looks to be moving eccentrically. No noise whilst spinning prop.
There is some forward/aft play in the prop from the lower gear housing, about 3 mm.

No recent grounding (did over a year ago - but fixed then), quiet sandy area and very salty water. Prop in good order. The ONLY new thing is i took the prop off to regrease recently.

Thoughts include: likely to be lower gear area as reproduced by hand out of gear, bent prop shaft - but no recent damage? bearings in lower gear housing gone?



Thought appreciated, Thanx

Re: Low speed vibration

Take the prop off and set up a dial gauge on the end of propshaft. Any more than 0.006" run-out and the shaft needs to be replaced. If you can see it moving, it's WAAAAY more than 6 thou. 1/8" (~3mm) longitudinal movement is normal. Any lateral movement would indicate worn bearings and/or propshaft....

Chris.......

Re: Low speed vibration

Recheck that you put the thrust washer in correctly when you greased the prop shaft.
And yup, visible shaft runout means you need a repair.

Re: Low speed vibration

Thanx

Took prop off and ran it in gear. Unfortunately Shaft still looked eccentric in the center - i assume it is indeed WAAAY out. It's in the shop.

Cheers