Mid-shaft bearing A27

[motthediesel]

Well, I've installed the intermediate bearing on my prop shaft, and there were a few surprises along the way.

I spent a good bit of time insuring that the new bearing (mounted in the keel cavity just under the fuel tank) was perfectly aligned with the stern tube. I made up steel discs to hold a string down the center of the bore. That string was then extended ahead to the spot where the mini-bulkhead would be tabbed in to hold the bearing.



I was curious to see where the shaft coupling would now line up with the gearbox. When I had changed the engine mounts originally, I saw that there was so much flex available in the long overhang of the shaft from the packing gland that it was impossible to align the faces of the coupling. It was easy to swing the end of the shaft around in an eight inch circle -- where the hell was the center line?

So, I really wasn't surprised when I now found the coupling faces looking like this.



Yes, the engine was nearly 3/4" to port of the drive center line. Those excellent Lehman mounts give a lot of lateral adjustability, but mine had not been moved in 35 years, and both rear mounts were rusted solid, no amount of banging or prying would move them. So, they were removed (one at a time, of course) and taken to the shop to be attended to. Here again, I used the old OMC flywheel puller to push the rods from the cast iron pinch-sockets.



To be continued....

[motthediesel]

Continued...

After they were removed, they were cleaned with a wire wheel and then greased. After both were done and re=installed, the engine was boosted over to starboard, with this result.



The wonder of this is, how that could ever have worked for all these years? I think that can be explained by the flexibility of the long overhang, and of the Federal flex coupling. A suspicious engineering mind might suspect that the reason they used the Federal couplings in the first place was that they found that they could not properly align the drive as-built, at least in a quick production manner.

Further evidence of the long term mis-alignment might be found in this, the rubber liner from the cutless bearing I removed. Note how it is worn away totally on one side at the end.



Anyway, I'm pretty convinced that this will now "shake no more" -- we'll see I guess

Tom

[Bob Noodat]

Great job Tom! It's the unanticipated stuff that always takes the time.

It surprises me that some kind of UJ/CVJ is not standard, but that would introduce expense, time, another bearing etc. and if you are trying to make a buck, or just break even, at boatbuilding then the "Git'r done" solution will no doubt always win.

[WillieC]

Now that is some more very nice sleuthing and execution.

The WillieC with its 84" bent shaft and rotted 40 year old mounts put up a heck of a racket. Now instead of rocking out to Iron Maiden, we've got it down to Johann Strauss.

Looks like you have the added benefit of adjustable mounts. These old VPs use shims. I tried finding suitable adjustable mounts, but found I could make these work. I also installed an R&D flexible coupling after aligning as close as I could get with feeler gauges.

Nice work and great pictures!

[sail149]

Great job Tom! It's the unanticipated stuff that always takes the time.

It surprises me that some kind of UJ/CVJ is not standard, but that would introduce expense, time, another bearing etc. and if you are trying to make a buck, or just break even, at boatbuilding then the "Git'r done" solution will no doubt always win.

Unfortunaly UJ/CV Joints are not intended to take thrust. There is a set up where you use a thrust bearing first then a UJ.
The early 27's came with a middle bearing but later versions made by albin themselves left it out! Cheers Warren