Rich,
Interesting topic. I can't help but wonder how many people can measure to
..001. Shaft measurement (OD) is fairly straight forward, but inside measurments
(ID) of the housing require a device ...the name of which I don't recall.
And if they can, what are the odds that the center axis of the housing is
that of the shaft. What are the odds that the shaft is straight..even if new?
I.e., the run-out.
To complicate things further, when the engine is spun up to 2,500 rpm,
isn't the torgue of the engine going to cause misalignment by at least a
few .001's? Maybe a good arguement for U-joints and pillow blocks?

I wonder what the maximum clearance is that would still provide a
"water bearing"..any idea?

As I say..interesting..
Norm B
On Tue, 14 Jun 2005 20:11:50 GMT, Rich Hampel wrote:

No. besides misalignment, wear can occur by abrasion of the
undissolved contaminants in the water ... silica particles, etc.

How to measu after you perfectly align the engine, put a dial
indicator on the shaft at the cutless bearing and 'move' it then
relocate the dial indicator 90 degrees on the shft and move the shaft.

Each manufacturer of cutless bearings (the good ones) will have a
specified 'installed' clearance. What I mean by installed clearance
is that the bearings inside diameter will become smaller when you
press/push it into the housing journal.

When you replace to a new cutless, accurately measure the shaft to
0.001", remove the bearing from the housing and measure the inner
diameter of the housing to 0.001". Simply give these dimensions to
the bearing supplier. Obviously the shaft must be fairly free of
defects such a galling, pits, etc. or the shaft should be
remachined/polished back to 'true'. Surface roughness on the shaft
will promote bearing wear (during 'start-up', when the shaft is no
supported by the water film and the bearing material is actually
touching the shaft. Otherwise when running the shaft will be prevented
from touching the shaft by a thin film of water - a hydrodynamic
bearing. Thats why the sizing is fairly critical as the clearance is
VERY important. .


In article .com,
wrote:

Is wear in the cutless bearing determined by how well the engine and
shaft are aligned?