1GM alignment on 25D

[Bruce Barber]

Any bad experiences out there aligning a 1GM to the shaft on a 25D? I seem to be having one...

I'm not doing the work, though - I'm having Bay Shore in Annapolis (a reputable firm) change the engine mounts, in addition to installing a new cutlass bearing, stuffing box hose, and propeller zinc (these are all complete.) The problem they're now having is that, even with the mounts and engine as far to starboard as the engine bed bolts will allow, there's still an excessive gap (about .008", twice what it should be) between the transmission flange and the (new) coupling, on the starboard side. The gap stays the same whether they rotate the shaft or the transmission flange, so it doesn't seem to be a coupling squareness-to-shaft problem, but a real misalignment. Until now, the engine bed bolts have been pretty much centered in the mount slots, at least on the visible forward end, so assuming their procedure is OK (which I have no reason to doubt), there's been poor alignment for probably 26 years. There is possible evidence of this - they found metal contaminants in the transmission oil (on the basis of that, I had them overhaul the transmission, which had been making strange noises late last season anyway.)

Their proposed alignment solution involves modifying the "L" brackets that land on the mounts to allow more movement to starboard (this turns the "L" bracket holes into slots, not an ideal situation, although I could have them fill the existing holes with weld metal and then redrill.) Another downside to their fix is that the heads of the "L" bracket-to-engine bolts then will contact the FRP engine bed stringer on the starboard side. To get around this, they would have to bore out a clearance hole in the inboard face of the stringer, and it would have to be big enough so that there's no contact as the engine bounces around. I think the system could live with that, but it certainly offends my sensibilities.

I'd be happy to hear any suggestions, although I think we're probably locked in to this approach. Mainly, I'm curious as to whether any of you have had similar experiences. You'd think that Cape Dory would have used the same template to drill the engine bed holes on all 25D's, so maybe there'd be some consistency. Of course, the basic problem may be at the other end of the shaft, with a long-misaligned stern tube.

Speaking of which: Another strange thing that they found was that four slotted setscrews had been installed to keep the old cutlass bearing in place, and that a lock-wire had been run through the slots, around the end of the stern tube (this had all been hidden beneath fairing goop), AND that the tube had been grooved around its circumference for the wire! This groove was deep enough
that it actually penetrated the tube in a couple of places. I guess that, over the years, the goop was structural enough to keep the end of the tube from coming completely loose. Has anyone else seen something similar?

[Ray Garcia]

I am doing all the same work on my CD27. I am up to the alignment part as well. I'm saving that task for a more temperate day. Please pardon my ignorance (maybe I am missing a particular detail), but why can't the mounts be milled/filed out a little bit on the starboard edge? The material is cast aluminum, and you only need .008 or about .2 millimeters to be back in the groove. I do not believe removing this amount of material from the mounts would affect their structural integrity. If I were using this approach I would make sure the bolts are torqued down well along with using a thread locking compound. A slightly oversize flat washer would also help. This might be an easier fix than messing around with the engine beds. Again, maybe I am missing a little more detail to your actual installation. Just a suggestion.


Picture from new mount installation. Go back a few posts to see a full description of my install.

[img]http://www.cd27spirit.us/images/board/8m.jpg[/img]


When I removed the "goop" around the cutlass bearing I also found the same stainless steel wire and 2 set screws. They also cut into the stern tube as you describe. I gather this was done to put more force on the tube to lock the bearing in position as well as to make sure the set screws remained in place. I have already replaced the cutlass bearing. The cutlass bearing presently sticks out about 3/8" from the end of the tube. This should not be a problem. I plan putting back the set screws along with the wire and fairing in with epoxy. As long as your yard followed a similar procedure, you should expect no problems with the replacement.


All the best.

[Bruce Barber]

...why can't the mounts be milled/filed out a little bit on the starboard edge? The material is cast aluminum, and you only need .008 or about .2 millimeters to be back in the groove.

Actually, Ray, they've decided to lengthen the slots in the mounts a bit, rather than mess with the engine brackets. As you say, it won't take much movement to get the slack they need. It's not the starboard edge, though, it's the port ends of the slots that will have to be extended, since they're trying to shift the engine to starboard.