Motor mount and damper plate suggestions

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Ray Taylor's picture
Ray Taylor
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Motor mount and damper plate suggestions

Good morning,

I’m planning on changing motor mounts and damper plate on our Universal M35B (2002 Mk2). I’ll probably do the work this winter but I’d like to source the parts and have them ready to go.   

I contacted PYI inc here the PNW and they can supply both.   Before I order I’m interested to hear what other owners have used and found successful.   There are lots of options and prices are all over the map.

Thanks,
Ray

Ray & Janice Taylor
"Mizu"
Hood River, Ore.
#2113 2002 TM
 

seabird
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Posts: 31

Hi Ray,

Did you ever make a purchase?  I'm wanting to do my motor mounts this winter as well.  Is this a DIY job for you or yard?  At ~$500 from PYI I'm thinking this could get real expensive, but can't decide if I want to get into it myself.

Thanks,
Erik

Erik
Chicago, IL
C-36 MK II #2106
 

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Chachere
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A number of members of c36IA have used the Vetus K75 mounts as replacements.  They are reputed to be better at damping the vibration.
We replaced our original mounts a decade ago. I believe I got them from Jamestown Distributors, but if you google you'll find a number of sources.  Rated for diesels up to 80 HP, and the footprint is the same as the OEM mounts on our boats.
I summarized the replacement process at comment #7 in this thread:
https://www.catalina36.org/forum/technical-discussion/engine-mounts-2

Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

seabird
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Thanks Matthew.  Are there some more detailed instructions on doing the alignment that I could reference.  I have noticed that I can't keep the forward starboard lock nut tight on the mouting bracket, which leades me to believe it's not perfectly aligned right now (it backs off after a few hours just enough to allow the washer under it to vibrate).  I'm really intimidated by this job, but maybe I shouldn't be?  It's been running fine and doesn't seem to vibrate too much except when idle/neutral (based on what I've read on this forum this engine does vibrate a lot at low rpms), but it's not like I feel like the whole boat vibrates or rattles away.  My fear is that if doing the alignment is a super techinical process of lining up coupling to very fine tolerances I may make it even worse.  Also, the links to manuals on your discussion are dead and are for MKI - so if I could find a MKII guide would be nice to read through if anyone has it.

Erik
Chicago, IL
C-36 MK II #2106
 

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Chachere
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Hmm.. the links seem to work fine when I went and checked them just now.  
The C36MkII manual should be here: www.catalina36.org/sites/default/files/legacy/C36MkII_Owners_Manual.pdf

But I don't think its any different than the MkI.   As I wrote in my post back then, Don Casey's "This Old Boat" (in the 2d edition  at pp 179-183) or Nigel Calder's "Boatowner's Mechanical and Electrical Manual" have excellent write-ups of the alignment process.   Its not brain surgery, just requires some patience.   And from your description of the vibration (or lack thereof) does make it appear that things are relatively OK (If the locknut is getting loose, maybe needs a lockwasher added? if I recall correctly, we have 2 nuts on each of the mounting studs so that they can be locked against each other).

   To me -- from unfortunate personal experience -- perhaps the #1 reason to check the alignment is to assure that the prop shaft is relatively centered in the shaft log tube and not touching it.   Over time, as the mounts wear, I think the motors tend to settle, leading to the shaft abrading away the fiberglass shaft log tube through the hull (if I recall correctly, the inside diameter of the shaft tube is 1-1/4" (31.8mm), which means a perfectly centered 1"(25.4 mm) prop shaft has just 1/8" (3.2mm) of clearance)(the shaft log tube  has an outer diameter of 1-5/8" (41.3mm), which means its walls are only 1/4" (6.4mm -- which can be eroded away rather quickly).   And since the inboard end is not visible due to the stuffing box hose or PSS shaft seal (what have you), you can only visually assess this from the outboard end (either while the boat is on the hard or a quick dive).  Take it from me, fixing a worn shaft log tube is a nasty repair job -- www.catalina36.org/forum/technical-discussion/shaft-tube-removal -- and easily avoided by checking the alignment occasionally. 
 

Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

seabird
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Posts: 31

Thanks Matt.  I agree, I've read through Calder and Casey's books on the topic this week and ordered the tools I didn't have for the job.  I'm still not totally sure how to id a failed mount - espeically with the large metal cap on these ones.  The mainsail article was very informative, I was afraid I was feeling the stud turn in the rubber, which I now know is impossible because it's welded to the cap.  Maybe I'll take a few pics this weekend if I'm still unsure.  I've only had about 15 minutes to work on this since I first brought it up, so hopefully the weekend gets me to a solution.  Thanks for the advice and links.

Erik
Chicago, IL
C-36 MK II #2106
 

Ray Taylor's picture
Ray Taylor
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Posts: 72

I should have been more clear.  I’m looking for anything new regarding motor mounts/damper plate.   The forum has good information and Leslie Troyer wrote a great article in the Spring 2020 Mainsheet.   I’m replacing our Hurth ZF10 with a PRM 90 gearbox and thought I’d do motor mounts at the same time.

Eric,

Only you can determine if this is something you want to get into.   The video series below is for a ski boat but is very good.
https://www.youtube.com/watch?v=5UqniaiggKA
Since you already have one engine mount that’s loose it is probably out of alignment. So IMHO you don’t have anything to loose.  I’d start by carefully inspecting your current mounts.  If they look good, you may be able to lock the nut in place with blue locktie or VibraTite VC-3.   If the original engine mounts are still serviceabl there is no reason to change.   Although it’s seldom this easy, it’s possible that adjusting your one loose mount and locking the adjusting nut in place with some VC-3 puts everything back into spec.   

https://marinehowto.com/replacing-motor-mounts/

Ray & Janice Taylor
"Mizu"
Hood River, Ore.
#2113 2002 TM
 

seabird
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Posts: 31

Agreed I probably have nothing to lose.  The youtube video was helpful.  Yesterday I attempted to tighten down the loose lock nut.  I held the adjusting nut firm with a wrench as I tightened the lock nut, so I was quite confident I didn't actually adjust the mount at all.  However, when I started the engine the vibration seemed a little worse and within a few minutes the nut was loose again.  When I shifted into forward idle it sounds horrible and if it wasn't misaligned earlier it clearly is now.  I am assuming this confirms that the mount needs to be replaced as I can't think of why simply tightening the lock nut would throw it out of alignment.  Anyway, ordered a feeler gauge today and will take a stab at alignment this weekend.  I'm going to try and re-align the original mount first and see how it holds, but I'm trying to source an OEM replacement as well so I can replace it if needed.  Thankfully, this forward starboard mount seems pretty easy to access so hoping at worst I replace that one to get through the season and mess with doing the rest this winter.  Thanks for the advice and will keep posted on how it goes.

Erik
Chicago, IL
C-36 MK II #2106
 

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pkeyser
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I'm sure there would be a lot of interested readers to learn details on how the PRM 90 conversion goes. 

Paul & Wendy Keyser
"First Light"
Newburyport MA/Rye NH
2005 C36 MKII #2257
Wing, M35B

seabird
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Posts: 31

Any advice on breaking loose the coupling bolts.  It's proving much harder than I anticipated.  Should I soak them in some PB blaster or something?  How do stop the prop shaft turning while working on the bolts.  I'm assuming you can brute force this without damaging something else like the transmission?

Erik
Chicago, IL
C-36 MK II #2106
 

Ray Taylor's picture
Ray Taylor
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Posts: 72

Eric,

Congratulations on getting started.  As you’ve found out boat work is not a direct path.

My coupling is connected to the transmission with 4 bolts and nuts.   If yours is the same then you can put a wrench on the bolt and another on the nut which should limit the rotation.   Worst case, support the backer wrench with a wood block (think wood block in bilge supporting the wrench from turning).

Penetrating oil will help and PB blaster is very good.  Put a liberal does on and let it sit overnight.   I normally use Kroil because the odor of PB blaster is disturbing.   A trick is to spray some in the cap outside the cabin, then distribute with a small brush.   
Once you’ve got the penetrating oil doing its job, look over the system.    I’d start by drawing a sharpie line across the hub and coupling as a witness mark. 
Put the gearbox in neutral and turn the coupling by hand.  It should be smooth but difficult to turn.   Use your senses to feel/hear if the shaft is bound up or rubbing.  I suspect that it will turn part way then start to bind.   
Inspect each motor mount, wiggle the engine and see what they do.   The motor mount adjustment bolt is secured to the engine with an L bracket.   Tighten the Allen head screws attaching the L bracket to the engine block to ensure they are tight. Now go back a try to break the bolts free,  I know I said overnight but it often works quicker.   If I doesn’t work, put another coat of penetrating oil on and go back to plan A.   

Paul,
I'll update on the PRM 90 D2 installation.   Like I said before, hoping to do it off season.

Ray

 

Ray & Janice Taylor
"Mizu"
Hood River, Ore.
#2113 2002 TM
 

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Chachere
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Just be careful with the PB blaster -- I've read that it can damage seals (such as the rear seal on the transmission), so keep the spray very controlled.

Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

seabird
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Posts: 31

Yikes, I hadn't considered that...  It's a pretty fine spray and I obviously targeted the bolts with it.  How far off base would I have to be penetrate the transmission?  I only got one bolt over the weekend, so the other 3 are still soaking.  Hoping to get them tonight and move on with the adjustment.  I assume if I damaged the seal I'd see a loss of ATF somewhere?

Erik
Chicago, IL
C-36 MK II #2106
 

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Chachere
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I don't know -- its just something I've read in various places on the internet, the reliability of which is always open to assessment.   But see this post by Mainesail, who I consider very knowledegable: www.sailnet.com/threads/pb-blaster-penetrating-oil-warning.33279/

If the spray is well contained coming out of one of those straw applicators I assume you're o.k.   Out of caution, however, maybe better to spray into a small container and apply with a small brush.or Q-tip

Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

seabird
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Posts: 31

Matthew,

So I got the final bolt off at lunch, now I can (finally) start the alignment tonight or tomorrow.  I was reading through your post https://www.catalina36.org/forum/technical-discussion/engine-alignment-a... about axial alignment;Your fear seemed to be you'll uncouple it, drop the shaft an 1/8" and then just end up aligning the engine to an improperly aligned prop shaft. 
Calder's book recommends supporting the prop shaft with a pulley or something from above if it's very long, but in our boats there is maybe 2 inches of shaft protruding from the stuffing box (circled in pic).  I know theoretically the hose between the stuffing box and the shaft log is flexible, but it honestly feels rigid enough by touching it that I imagine it wouldn't just droop enough the minute I disconnect it to be way out of alignment (underlined in photo).  Boat's in the water and diving on it isn't an option (or at least would like to avoid; fresh lake water and A/C power on the dock are a bad mix).  Since you did this on the hard sounds like you were able to confirm prop shaft alignment from outside the boat.  My plan is to just place a few blocks of wood under the stuffing box before decoupling, but maybe I'm over simplifying, so just wanted clarification on your concerns and solution from that post. 
Additionally, the coupling on the transmission is not a complete circle, two sides of it are cut away, which seems to negate the ability to take a measurement on all 4 sides of the coupling as it is currently faced together (arrow in pic)...  Is that an issue?  Do I just keep rotating that transmission coupling 90 degrees and taking measurements?  I'll have witness marks to line it back up correctly of course. 
Sorry for all the questions, but I just want to make sure I don't screw anything up as this a totally new job to me.  Just FYI in case I'm sounding really dumb on this forum, I'm not totally mechanically un-inclined, I replace fuel filters, belts, hoses, starter motors and winterize and do all other routine maintenance seemingly without screwing it up, but this feels more technical than those simple R&R jobs so I'm asking a million questions.

Erik
Chicago, IL
C-36 MK II #2106
 

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Chachere
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That was a bit of a blast in the past reading that post from 10 years ago, when I was a new owner.   I think your plan makes sense.  
I would imagine you can always double check that the prop shaft is reasonably centered when you are, say, anchored somewhere away from AC power and can dive it.
 

Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

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