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kra
08-30-2004, 04:30 PM
I have a Seaforth double ender that I am installing new engine and drive train in.
when I removed the very worn cutlas bearing from the fiberglass stern tube it had a pvc plastic tube split lengthwise around it to make it fit.
The old bearing was 1 5/8" diameter but the stern tube measures about 1 13/16" id.
My question is should I install new bearing this way or would it be better to order a 2" bearing and turn down to fit? Are there other better ways to do this?
Thanks for suggestions.
Randy

Gary E
08-30-2004, 06:42 PM
Those bearings are made in standard sizes for a reason, EASE OF REPLACEMENT... For that reason alone I would not alter a 2 in OD even if it has the excess stock. I would be altering the hole that it mounts into so that the next time it's a simple replacement.

kra
08-30-2004, 08:11 PM
Gary E
I can't drill out tube to fit 2" because wall thickness of stern tube would be too thin.
I might be able to build up inside of tube for a few inches and redrill for proper fitting 1 5/8"
though.
thanks
Randy

Gary E
08-30-2004, 08:31 PM
Forgit buid up and drilling.

Depending on the condition of the stern tube you may be able to fit a proper ID tube or bushing into what you have now by having this bushing centerless ground to a shrink fit so it fits into the stern tube. Then freeze it with dry ice and install. The result should be the proper ID for the normal bearing outside dia. If you made the fit to tight and the bearing wont fit, hone this hole to proper size.

kra
08-30-2004, 08:56 PM
Gary E
thank you for suggestions.
That sounds like a good way to permanently solve problem.
Randy

JimConlin
08-31-2004, 12:20 AM
Another idea to consider-

NOTE I am not a boat mechanic, nor do I play one on TV. This is an idea based in no experience. The price is right.

I'd consider casting the bushing of filled epoxy within the stern tube and around a stock bearing.

Get the largest and longest cutless bearing which will fit, however sloppily, in your glass stern tube.
Get a couple of 60cc plastic syringes from the local vet/home care shop or such.
Sand out the interior of the FG stern tube. You want a bond to this surface. Drill a couple of holes through the bottom of the tube, same size as the nozzle of the syringe.
Polish the outside of the bearing and lube the bearing well with several coats of paste wax and spray with PVA. Same for the shaft.
Install the shaft and the cutless bearing.
I'm not sure how finicky to be about alignment here. The easy (for me) recommendation is to align the engine... so that the shaft is centered to .000001" within the tube. Personnaly, I'd be a bit more casual.

Shoot the void between the tube and the bearing with epoxy thickened to Skippy PB consistency with cabosil or whatever. Techniques for damming the ends of the void and ensuring fill are left to the student.

When the epoxy is at the green stage, pull the shaft, trim the extra googe at the back end.

When it's cured, pull the bearing out, clean things up and drill and tap your nozzle holes for setscrews.

Replace the bearing, with setscrews, and you're done.

Gary E
08-31-2004, 05:26 PM
Jim,
That might actualy work. Definatly install the shaft aligned with the engine but "centered to .000001" within the tube." is not even measurable, stick with a .0015 or .002 feeler gage and you will be fine. Maybe there is a way to get Marine Tex epoxy which is the consistency of peanut butter pumped in there with a "use it this one time" grease gun or some other way to make sure you completely suround the bearing.

kra
08-31-2004, 07:08 PM
I appreciate all ideas
just found in my scrap pile a piece of stainless pipe that measures a tight drive in fit O. D.(1 3/4"+,-) and close enough to hone I. D. for a 1 5/8" bearing.
What do you think of using stainless for a bushing between the fiberglass tube and the brass/bronze bearing?
will this corrode and make bearing removal even worse in the future?
I am not sure of type of stainless but I think it was 316.
This would work with very little effort and is tempting to use.
Again I appreciate opinions and advise already given.
Randy

Gary E
08-31-2004, 07:32 PM
Randy,
I think you will be fine doing that, I would.

As far as the disimilar metals? a dollar aginst a donut hole someone will explain the reason why it's not compatable, BUT since there are thousands if not millions of bronze props screwed onto stainless shafts with no problems I see no problem.

G

JimConlin
08-31-2004, 11:59 PM
The metal bushing approach leaves unsolved the issue of alignment. This can be a royal pain.