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-   -   Removing tranny/bell-housing on a Universal M4-30 (https://www.sailnet.com/forums/gear-maintenance/50625-removing-tranny-bell-housing-universal-m4-30-a.html)

Pub911 01-18-2009 09:58 PM

Removing tranny/bell-housing on a Universal M4-30
 
From the shop diagrams, it looks like I have to remove the entire bell housing assembly and aft motor mounts in order to remove my tranny for servicing. See attached that's led me to this conclusion - that and the fact that I can't find any bolts to take off!!!

Any guidance on easiest approach that won't leave me with unintended consequences (I'm worried about messing up propshaft alignment and wrenching the forward motor mounts, but there may be other hazzards as well).

Thanks, all.

http://www.marinedieseldirect.com/ca...ors=&comment1=

Maine Sail 01-18-2009 10:51 PM

Looks
 
It appears your tranny is just mounted directly to the bell housing. You'll need to remove the top rear motor mount bolts and loosen the top fronts about 3/4" then jack the engine enough to clear the tops of the rear motor mounts. Once the engine is jacked high enough place blocks of wood under the oil pan to support it.

Depending on your arrangement you may need to disconnect the wet exhaust to jack it up.

http://www.pbase.com/mainecruising/image/107634140.jpg

You are now ready to unbolt the bell housing and slide it off the engine.
http://www.pbase.com/mainecruising/image/107634145.jpg

It's a good idea to replace the damper plate while you are in there. They are usually good for about 1k hours of use but it's still wise to replace it while you have everything apart. When you replace a damper plate always purchase new retaining bolts... Oh and use an impact wrench and PB Blaster to get the old damper plate bolts out of the fly wheel. Using an impact wrench to break them free will reduce the risk of breaking a bolt dramatically.

Impact wrench & PB Blaster:
http://www.pbase.com/mainecruising/image/107634150.jpg

There is 100% NO WAY to avoid an engine alignment after doing this job!! You must re-align after you're done..

sww914 01-18-2009 11:02 PM

Wow! What a nice writeup and nice pictures.

Pub911 01-19-2009 10:22 PM

Thanks, Maine Sail. I agree impressive pictures and thorough description. But what's even MORE IMPRESSIVE, is the condition of your bilge. My God, Maine, you could melt butter and eat lobsters out of that hold. :laugher Nice set up!!!

One quick verification: It looks as though your set up has the flywheel facing forward, hence your motor mount comments should be reversed (e.g. loosen water pump end mounts, undo flywheel end mounts) if my shaft log is a straight shot aft of my tranny. Right?

Also, a follow-up on the alignment. Just how do you do that? I mean, I get the up/down setting of the motor mounts, but how do I know when it's centered. And is there a port/starboard setting?

Thank you very much!

Maine Sail 01-19-2009 11:39 PM

Quote:

Originally Posted by Pub911 (Post 434567)
Thanks, Maine Sail. I agree impressive pictures and thorough description. But what's even MORE IMPRESSIVE, is the condition of your bilge. My God, Maine, you could melt butter and eat lobsters out of that hold. :laugher Nice set up!!!

One quick verification: It looks as though your set up has the flywheel facing forward, hence your motor mount comments should be reversed (e.g. loosen water pump end mounts, undo flywheel end mounts) if my shaft log is a straight shot aft of my tranny. Right?

Also, a follow-up on the alignment. Just how do you do that? I mean, I get the up/down setting of the motor mounts, but how do I know when it's centered. And is there a port/starboard setting?

Thank you very much!

I used the term "rear motor mounts" because I figured you did not have a v-drive, as I do, based on your description.

Sorry you think that is clean! That is dirty by my standards but I was working...

Check for shaft centered from outside the boat looking at the location of the shaft in the stern tube unless you have a full keel. As for port stbd you actually slide the motor mounts left and right. Take your time and buy good feeler gauges. The max allowable variation is .004" but with a small coupling you should be able to get to .002 or .003 as checked at 12:00, 3:00, 6:00 & 9:00 with teh coupling bolts loose..

One tip though. After you have moved a mount and re-tightened it shake the engine around by hand a fair amount to settle it in the mounts and then check your alignment. By not shaking or wiggling the mounts to re-seat the engine in them you will have very poor odds of getting a good alignment..

Adjust, tighten, wiggle, check, adjust, tighten, wiggle check over and over......

Pub911 01-20-2009 12:03 AM

Thanks again. Not sure I follow, sorry for being thick-headed. How am I going to get to those tolerances by looking up the shaft log, it's 3ft long and has a cultass bearing in one end, and the other end is another 3 ft from the tranny.

While we're at it, do I need a 'pilot shaft' or similar tool to aling the clutch-plate, like you do when you put a clutch in a car?

Thanks, Maine.

JHJensen 01-20-2009 07:55 AM

Paying attention to shaft alignment and driveline care
 
Quote:

Originally Posted by Pub911 (Post 434638)
Not sure I follow, sorry for being thick-headed. How am I going to get to those tolerances by looking up the shaft log, it's 3ft long and has a cutless bearing in one end, and the other end is another 3 ft from the tranny.

While we're at it, do I need a 'pilot shaft' or similar tool to aling the clutch-plate, like you do when you put a clutch in a car?

Pub,

I don't think you are thick-headed at all. I think you are asking some great questions and I would suggest you get Nigel Calder's book Boatowners Mechanical & Electrical Guide 3RD Edition, if you don't already have it. It is considered by many, both professional and recreational boaters alike, myself included, to be the book!. You will be able to read up on the systems and understand better what you are taking on.

Drive system alignment is covered quite well in Calder's book. Here is another link on the subject. Marine Engines : Drive System Alignment by David Pascoe, Marine Surveyor

You do not need a pilot shaft as the clutch like plate you see in the your diagram is the damper plate which is bolted directly to the fly wheel and therefore is already aligned with the input end of the reverse gear. It's job is to absorb the impact of going in and out of gear, just like the clutch plate does on a manual transmission on a car, but there the similarity ends as the damper plate is never disengaged from the flywheel.

Maine Sails' wonderful pictures and description of alignment measurements/procedure have to do with "moving" the engine to get the two coupling faces as close to parallel to each other as possible, which is usually .004 inches. This is done by measuring how far out of parallel the faces are by using feeler gauges in the gap between the coupling halves on the outer edge of the flange at 12, 3, 6 and 9 oclock which will indicate how straight your drive system is from the front of the engine crankshaft to the end of your prop shaft.

The alignment procedure is critical and key to proper drive line operation, and component longevity (meaning: motor mounts, cutless bearing, stuffing box, transmission output shaft seals and bearings!) It does not matter if the vessel is a large commercial boat or a small cruising auxiliary such as we are talking about here, it must be done and the same rules apply except for the costs when the system fails.

The v-drive Maine Sails has can be a lot of "fun" to work with. :D because of the way his drive line is folded back over itself. His system also absorbs propeller thrust differently than a straight inline system like yours does and in some ways is more sensitive to damage from misalignment! You can see he takes pride in and great care of his vesel and her systems! I will try to post some photographs of the same drive that was not so well looked after in another boat, but that is another story. Another thing of note about his v-drive is the output shaft is hollow and the prop shaft actually passes through the output shaft on it's way out to the stern tube. This design is kind of cool in that it keeps the coupling out where it is easy to get at. Many other V-drives have output the shaft and coupling down under the drive where it is hard to access for work.

Learning how to align the drive system is an exercise in time and patience depending on your mechanical skill level. If you have not done it before or are not sure about the procedure. It may well be worth having a professional check and do any final adjustments before and after the vessel is in the water to make sure you are spot on or it may cost you big time in the long run (think of the parts list above in the preceding paragraph $$$). Not to mention having a drive line casualty while on a long summer cruise away from your home port because of drive line issues that should have been addressed by a proper installation and alignment in the first place. The delay and change in plans can also have an effect on crew attitudes as well :clobber

Nothing like opening the engine compartment at the end of a long day of sailing and seeing transmission fluid all over the pan under the reverse gear!:puke :eek: Along with the coupling set screws worked loose and the coupling wobbling on the shaft. I can tell you from personal experience this is where Maine Sails V-drive is an advantage and comes into it's own in terms of access, removal and repair. :D :D

Another side effect of misalignment and a strong motivator for proper care :) of your drive system is if you have a dripless stuffing box will be possible large amounts of water appearing in your bilges at times. I also suggest installing a high water alarm. Your vessel won't sink (at least while you are on board!) but having water in the bilges when you expect them to be dry can be disconcerting! :eek: :eek:

Your alignment can be gotten pretty much done on the hard but then should be checked again after the vessel is launched and the mast stepped and tuned to working tension and she has had a few days to sit in the water and get her "in water" shape back. A boat will sometimes change shape enough to throw shaft alignment out enough to cause problems. The least of which can be vibration or later premature wear and failure of critical parts.

Pub, all in all this will be a great learning experience for you in the ongoing effective management, operation and maintenance of your vessel and I encourage you in your endeavors.

I also took a look at your posts and see that your vessel is "mature" in terms of her age. Since you are going to be taking things apart. I see you have already done a great deal of work on your vessel. Do you know how old your motor mounts are? Now may be a good time to replace them as well depending how old they are. That way when you put her all back together you will have a clean slate in terms of your drive line.In other words if it was my boat or clients I would want to be starting on a level playing field which means checking all of the parts of the drive line. Cutless bearing, shaft ( is it straight not pitted?) Is the shaft half of the coupling square to the shaft? Is your shaft the proper lenght(not more than shaft diameter between the last bearing (cutless) and the forward end of the propeller. You have to look at your drive line in terms of all of its parts and if you start next season knowing what the status is of all the components you will be able to isolate and mitigate any small problems before they become big ones.

Good Luck!

John
ABYC Certified Master Technician

Pub911 01-20-2009 05:14 PM

Thanks, John.

I really appreciate the detailed explainations and the reference materials.

The link in your reply gives me some confidence that I should be able to get it done with my own skills & tools. The link also gives some good diagnosis tricks to test the results of my efforts. I was also encouraged to know that my set up (prop shaft diameter of 1") is less sensitive than larger shafts.

Just to fill you in on a few things that came up in your response. The boat is older - 1972 NorthStar, repowered with a Universal M4-30 in 1993. The mounts were replaced in '93, so I'll be looking at their condition.

The shaft and coupling were replaced in 1998 due to a miscue by a surveyor that caused the shaft to bend (he tried backing out of the sling before the sling was out of the way on a short haul after a sea-trial - yikes!). So those parts are now solid and true. I also have a dripless stuffing box installed, replacing the hard-to-reach stuffing box. The cutlass bearing looks good and is just 2 seasons old.

Thanks, again for the very informative and helpful replies.

:)


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