Re: [Amel] Re: Autoprop Bearing Replacement

Mike Ondra


The Autoprop went back together quite easily. As you noted, the bearing
races are hardened steel, not stainless, and are a fairly loose fit in the
recess. In conversing with AB Marine, the Autoprop dealer, they did not
mention your approach to breaking the race loose, nor that the fit was loose
in the hub, hence my more complex approach.

The beauty of the ¼-28 treaded holes through the hub is the next time the
races can be easily popped using the ¼-28 wedge bolts that lock the blade in
place. I do not recognize there being a “sealed cavity” in the prop as the
nose cone is not water tight.

The picture you have posted shows a destroyed race and bearing. Ours, after
about 1500 hours showed little wear, just a bit of chatter as the bearing
was turned, a roughness if you will, not very visible, but not entirely
comforting either. May not have had to replace them, but we we’re already
pretty far along in the process so went ahead with it. The reason to start
the project was occasional vibration while under power, and then the
noticeable wobble of the blades when examined on haul-out. We didn’t
initially realize that the wobble could have been taken out by simply
loosening the wedge bolt, tightening the retaining cap, and retightening the
wedge bolt. Knowing what I know now I would have simply done the adjustment
and rechecked in another 500 hours.


Aletes SM #240


From: amelyachtowners@...
[mailto:amelyachtowners@...] On Behalf Of amelliahona
Sent: Saturday, March 13, 2010 12:06 AM
To: amelyachtowners@...
Subject: [Amel] Re: Autoprop Bearing Replacement


As you have found, the removal of the hardened steel bearing races
is difficult . I don't believe these are stainless steel as stainless is too

soft for bearing races. Did you perhaps see the series of photos
that I posted in the photos section of this forum entitled "Autoprop
Service and Overhaul"? Also, I posted in the files section a number
of critical notes and hints on performing the overhaul including
thoughts on how to remove the races.

In that photo file I posted some photos with descriptions about how
to remove the races. These races are not a precision fit or interference
fit in their recesses. They are a LOOSE FIT but are usually held in place
by dirt, grime and old hard grease. All you need to do, is to get the
race rotating in its recess and you can do that by grinding a recess
into the steel race, then using a punch at an angle to get the race
rotating in its recess until it is somewhat loose, then tapping on the
back side of the hub and the race will fall out.

Did I understand it correctly that you drilled a hole through the hub
into the race recess? If so, how did you then plug that hole to
prevent ingress of sea water into the sealed cavity?

Could you also inform us about the condition of the bearings, seals,
and races that you found upon disassembly and the approximate
number of engine hours at the time of prop overhaul.

All the best,

Gary Silver
Amel SM #335

--- In amelyachtowners@ <>, "mike_ondra" <mdondra@...> wrote:

Haven't seen many postings on Autoprop bearing replacement. We are in
process now. The kit from AB Marine in Rhode Island was $750 for the
bearings and races, a bit salty. The blades had a bit a wobble after several
thousand hours of use, hence the decision to replace the bearings.

Following the instructions, the prop came apart quite easily until the
last step, removal of the inner lower track, the stainless bearing race
inset into the hub. No holes from the back to punch it out, no surfaces to
pry against. The instructions mentions several versions of the hub but no
clues as to how to extract, other than to contact Autoprop dealer for
further instructions.

Their suggestion to superglue stuff to the stainless race seemed dubious.
Second suggestion was to drill through the stainless and slightly into the
brass of the hub and thread the stainless to receive a bolt. The bolt would
be turned into the stainless, push against the brass and pop the race. This
was tried and succeeded only in stripping the perhaps too small bolt. A
larger bolt may have worked as it would have caulk the thicker portion of
the race and provided more thread surface.

Ultimately we drilled and tapped all the way through the hub. Then turned
a bolt through the brass from the inside just short of the stainless. Then a
bolt through the stainless snug to the bolt in the brass. Then turned the
bolt in the brass until the race popped out. All three came out fairly
easily with this approach.

We now begin the reassembly.

Note: The installation instructions provide a procedure for simply
adjusting/tightening the bearings should they be loose and cause vibration
or wobble. This would be the proper fix to try before spending the time and
money for a full bearing replacement. Scanned bearing adjustment
instructions posted with photos.

Photos under Aletes SM#240


Join to automatically receive all group messages.