prop shaft alignment

[Pat T]

Over the winter I pulled the transmission and installed a new damper plate. While at it I replaced the bellows on the PYI dripless shaft seal. This spring I notice I have wobble in the prop shaft. So I checked alignment and it is out more than the recommended .003 at the coupling. It is out on the stb. side. I have made several attempts on re-aligning but I can't get the engine to move to close up the gap. I can pry it over with blocks of wood but when I tighten things down it always opens back up. My Catalina mechanic is booked for at least 2 weeks and I don't want to wait that long. What is the procedure for alignment when starting allover from scratch. Everything is loosed up now. Yes, I have checked to make sure my transmission is tight too.

Also if you know of a good mechanic that does alignment in Chicago please let me know. Thanks.

 

[woodster]

have you tried moving the opposite corner the other way

 

[Warren Milberg]

I would check and make sure of the integrity/condition of the motor mounts and cutless bearing first...

 

[Don S/V ILLusion]

I second the motor mount issue. Alignment is a function of adjusting the mounts. It's impossible to adjust them if they are old and bottomed out.

 

[Pat T]

Yes I have tried moving the opposite corner. The cutless is good. I replaced it last year. Not sure how to tell if a motor mount is good or not? All I know is last year all seemed to be ok and now its not. I am trying to have a mech. out next week, hopefully. But if I get some ideas from this forum I'll go out and punish myself again this week-end. Thanks for the suggestions.

 

[Don S/V ILLusion]

Not sure how to tell if a motor mount is good or not?

If you know what they are supposed to look like, you can tell if one or more is bottomed out. Take a look at some pictures of them which you should be able to find on the internet.

 

[capejt]

They ay a picture is worth a thousand words. I changed out my engine mounts on my H33 two years ago, here's a new one next to an old one

 

[tommays]

depending on how what condition the coupling came off in , rust and other such stuff it offen becomes lose enough to be a problem

It certainly caused me problems until a new one was fitted and faced

The ailment is important because of stress on the transmission and such but should not cause a wobble

 

[Lee Hadjiosif]

How much more than the .003" is it? Sometimes you may not be able to align it that close. Did you consider that the wrong type of damper plate was used? Did you replace it because you had too much vibration to begin with? It's unusual for someone to replace the damper plate unless there is an incident with the transmission. Your boat is not that old...
Lee
S/V Adagio

 

[Pat T]

I am wondering if one of my mounts is worn. It does seem that it sits a little lower than the other ones. This is one of my aft mounts. If this is the issue can they be changed easily? Do you have to lift the engine out?

Damper plate was changed due to rattle of the springs at low rpm - a common problem with some of our boats. New damper plate is polymer(sp?) design. It solved the problem - no more rattle. And the coupling fit together real tight so no problems there. I think my issue, if any, will be a motor mount problem.

Or maybe I am not good at this whole alignment procedure. Still hoping to get someone out for a second opinion.
Thanks for the inputs. Keep the comments coming.

 

[Chris Patterson]

No you shouldn't have to pull the engine. I've put several in just prying up one end with a couple of 2X4s. Simple job.

 

[MitchM]

did you have to undo your prop shaft coupling to do the job on your transmission? if so , check that you followed the install directions on torquing down your coupling bolts. most manufacturers such as centa tell you to reinstall the coupling using a torquing pattern of #1-#4 to half the final torque then # 2- #5 then #3-#6 to half, not 1,2,3 then 456 cranked all the way down. Then do #1-4 , #2-5 etc. to final torque. this #1-4 pattern with 2 steps to the torquing keeps the coupling halves evenly bearing down and equally torqued around its circumference . that pattern will avoid the misalignment of the coupling which could be caused by cranking the bolts 123 totally tight to final torque then moving to 456. torquing the coupling down that way 123 could possibly be causing your .003 faceout.

if the old motor mounts gave you an aligned shaft before the transmission repair, i'd be surprised that you now need to adjust them to cure the faceout. have you measured face out at 12 oclock, 3 oclock, 6 oclock 9 oclock on your coupling ? am i understanding that only one of those measurements is 'out' .003? what are the other faceout measurements?

before you mess with the mounts: can you figure out how many threads are engaged on your existing motor mounts both left-right and fore- aft ? look at the nice picture posted by capejt. I'd mark the existing positions with tape before you start adjusting threads .

without access to a mechanic for a couple weeks i'd start at the coupling and redo that joint, use a torque wrench to make sure you have the right torque. see if you can closer to the desirable . 001 each of the 4 positions.. after that exercise if you have threads left to adjust, it should be a simple matter .

how old is the engine install on your boat, both in years and hours of operation? yanmar used to r ecommend installing new motor mounts after only 5 years chronological age as their soft rubber mounts would bottom out and the proshaft could go out of alignment. I didn't find it necessary to redo the mounts every 5 years but by 20 years, the mounts could not be adjusted any further and the mounts needed to be replaced.

MitchM
Nauticat 321 Eagleswing, port of Erie PA