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Old 11-06-2012, 01:01 PM   #1
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CV/Universal Joints

Good Afternoon - We are rebuilding (slowly) a 1977 MT 44' - Wondering if anyone on forum has had any experience with installing CV/U joints between the BW tranny and shaft coupling? Seems a good way to reduce vibration and noise. Thanks for any input. (The Fords are aligned but there is some residual vibration - possibly the props need rebalancing along with new cutlass bearings....)
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Old 11-06-2012, 01:35 PM   #2
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tit wont work because u joints are for twisting and the push from the props will tear them apart.if you had a pillow block bearing to take up the thrust from the shaft pushing against the u joints it will work, been ther done that, the bearing in the back of the tranny is made to take up that thrust.we did that years ago when we used flathead fords in clam boats with the car trannys,it worked good but rerverse was bad because of the gear ratio.high gear was good going ahead,they were the good old days
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Old 11-06-2012, 02:49 PM   #3
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Thanks for the feedback, Capt. Jerry. Hadn't thought about the thrust problem with U joints. May have to reconsider a flex coupling of some sort. There is some room to move the shaft aft but don't want to overdo it - as in leaving the prop hanging out to far past the strut...
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Old 11-06-2012, 03:01 PM   #4
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A true prop, straight shaft, good cutless bearing, good engine mounts, all properly aligned will not vibrate. A flexible coupling is a poor substitute for all of the above.

David
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Old 11-06-2012, 06:41 PM   #5
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David,
You have one of the most spot on posts of anyone on the forum but on this one I've got to agree AND disagree.

Kinda like dinosaur oil v/s synthetic. Don't need the synthetic at all. As to the C/V joint couplings I think they are the very best way to couple a shaking engine on soft mounts in a boat. The only installation that definitely dosn't need or can't use a coupling like Aqua Drive, Python Drive, Evolution Drive or other similar system is a boat where the engine is bolted hard and direct to the engine beds like most all boats in the 50s were. Those boats had very smooth engines w very heavy flywheels and big wood engine stringers/beds tended to absorb vibration. BUT now w very light engines (relatively) and engine mounts that allow the engine to move about I wonder how anyone can think of NOT using a flexible drive. BUT most engine installations do not have a flexible coupling and live long lives w an acceptable amount of vibration. That said would make one wonder why anybody would waste their money on flexible drives. I can actually answer that question. If you were fitting out a garbage truck you'd opt to spend money only on what works and what is needed to get the job done in a cost effective manner. If you were building yachts and none of your competitors were offering flexible drives and only the very rare buyer would even understand what a flexible drive was you'd opt no flexible drive. But if you were a yacht owner and were very serious about the smoothness of your craft and were intent on having your yacht fit out and operated in the very best manner possible you'd probably be interested in flexible drives. On some boats a flex drive will reduce vibration dramatically and on others not much or even not at all. I know this from actual experience. There is a fact here that promotes/sells flex drives and that is that the engine in a boat w flexible mounts shakes the devil out of the drive line/shaft and frequently that shakes the boat. It's a shame that one basically needs to install the flex drive to find out how much vibration will disappear. Even if ther'e is no vibration removed other advantages remain. There is no thrust on the transmission and no thrust on the engine mounts either. Engine mounts are compromised considerably to accommodate engine/propeller thrust. For that reason special engine mounts are used w the Aqua Drive and probably most others too to make maximum use of the C/V joint drive.

"U" joints won't work for this application obviously because of the thrust. I have been told by an Aqua Drive rep that the "plunging" capability of the C/V joint is necessary.

So no David you don't NEED flexible drive couplings but they are the best way to connect a soft mounted engine to a fixed propeller shaft.
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Old 11-06-2012, 08:06 PM   #6
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Manyboats; I'm glad I read your post today We hauled out in September and one of the projects we did was a engine alignment. My old boat has the Cat diesels bolted directly to the engine stringers and also has hard rubber disc bolted between the engine and the prop shaft flange. When we were finished the yard said I really need to consider installing better mounts to make it easier to align the engines. BIG BIG DOLLARS !! After reading your post I'm going to leave it as is. It works just fine and I can live with what little ( very little ) vibration there is. Thanks again.
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Old 11-07-2012, 06:06 AM   #7
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To install this CV style drive ,

1. you must use a shaft thrust bearing.

2. you must get the engine OUT of alignment as angular motion is required for the CV to have a good service life.

3. The use of very flexible mounts to reduce noise and vibration must be matched with a flex fuel supply , flex exhaust and slack in the wiring and flex in the engine controls..
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Old 11-07-2012, 06:44 AM   #8
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I have seen this type of Flexible Coupling in use on boats

R&D Drive Train Solutions RD Flexible Shaft Couplings, Damper Plates, Engine Mounts
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Old 11-07-2012, 01:53 PM   #9
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To be clear, the flexible coupling cited by Stray-Cat will address minor alignment deficiencies and thereby reduce vibration.
A system like the one produced by Aqua Drive and mentioned by many Many Boats
Aquadrive
provides a flexible coupling and also handles the prop thrust. This probably helps the transmission and allows for special (softer) engine mounts, further reducing vibration.
Right?
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Old 11-07-2012, 04:55 PM   #10
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Russell,
Yes I agree that's a good way to do it but you may be somewhat dependent on the stiffness of your hull to keep shaft and coupling forces within tolerable limits. With a stiff hull it should be fine.
Those Cat's must be smooth engines. Lucky guy.

FF,
Yes the optimal alignment is 2 degrees from straight.

Stray-Cat,
The R&D flex coupling is very good for engines that are on relatively firm mounts. Of course it is only about 1/15th as much money and trouble but there is the potential danger of doing serious transmission damage. That occurs only if the bolt heads come in contact w the transmission output flange. Then the shaft will hammer the thrust bearing and do serious damage. I once had to replace a transmission because of that. One needs to make sure they have the right size mount so it can take the thrust without pushing the bolt heads up to the transmission flange. Periodic checks should be made as the plastic may weaken over time. I like these couplings and would use one again but I'd be very careful to insure the bolts didn't touch. I'd probably get the next size up. Wouldn't be quite as flexible but safer.

Miss Rachel,
Right.
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Old 11-08-2012, 04:21 AM   #11
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I can't believe the one person here who has one hasn't posted a photo of his U-joint drive ... or commented on its performance.
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Old 11-08-2012, 06:17 AM   #12
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Quote:
Originally Posted by VixenII View Post
May have to reconsider a flex coupling of some sort. There is some room to move the shaft aft but don't want to overdo it - as in leaving the prop hanging out to far past the strut...
The link I provided is one way of reducing vibrations
But cross off prop balance and cutlass bearings first

Quote:
Originally Posted by Russell Clifton View Post
My old boat has the Cat diesels bolted directly to the engine stringers and also has hard rubber disc bolted between the engine and the prop shaft flange.
Is your hard rubber disk similar to the coupling in my link?

Quote:
Originally Posted by Miss Rachel View Post
To be clear, the flexible coupling cited by Stray-Cat will address minor alignment deficiencies and thereby reduce vibration.
A system like the one produced by Aqua Drive and mentioned by many Many Boats
Aquadrive
provides a flexible coupling and also handles the prop thrust. This probably helps the transmission and allows for special (softer) engine mounts, further reducing vibration.
Right?
Correct , the Aqua-drive is a top quality product
BTW the poly disk will handle prop thrust

Quote:
Originally Posted by manyboats View Post

Stray-Cat,
The R&D flex coupling is very good for engines that are on relatively firm mounts. Of course it is only about 1/15th as much money and trouble but there is the potential danger of doing serious transmission damage. That occurs only if the bolt heads come in contact w the transmission output flange. Then the shaft will hammer the thrust bearing and do serious damage. I once had to replace a transmission because of that. One needs to make sure they have the right size mount so it can take the thrust without pushing the bolt heads up to the transmission flange. Periodic checks should be made as the plastic may weaken over time. I like these couplings and would use one again but I'd be very careful to insure the bolts didn't touch. I'd probably get the next size up. Wouldn't be quite as flexible but safer.

Miss Rachel,
Right.
I agree,correct installation is critical,the coupling that I have seen in use has been in the boat over 10 years
It's not to be used as a shortcut for poor misalignment
The owner had a pro do the install

Quote:
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I can't believe the one person here who has one hasn't posted a photo of his U-joint drive ... or commented on its performance.
The Selene I ran had a Aqua-drive + engine mount isolation system
It was installed by the previous owner
No issues with vibration,and no issues with maintenance in the 4 years since original install
The engine was a Cummings qsm-11 rated at aprox 450hp
The cost of the Aqua-drive was $10k + installation
The motor vibration system ,which was a costly large stainless steel mounting and spring system brought the total cost to approx $40k including installation
I did not post a comment on this previously as most of the folks here have better uses for that kind of money
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Old 11-08-2012, 06:25 AM   #13
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I can't believe the one person here who has one hasn't posted a photo of his U-joint drive

A single U joint does not work well as the prop speed is not constant , depending on the amount of misalignment.

A pair works fine , look at almost every RWD old car and truck, but require a thrust bearing to operate.
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Old 11-08-2012, 10:56 AM   #14
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Here's a new kid on the block ... new to me anyway.

Welcome - THERMO BOAT Ltd., is the North American Distributor of products to make your boat experience WARM, QUIET, COMFORTABLE AND SAFE

The "hard rubber disk" I know of is more like a plastic disk and is called a " Shaft Saver". It's only mission in life is to shear off when one hits a rock and "save" other components of the drive. They are orange in color.

Stray cat wrote: "I agree,correct installation is critical," I fully agree. I installed my own AquaDrive and consider it a very fussy installation. My AquaDrive was the smallest and cost $1500 15 years ago.

Rick I can't believe I didn't take any pics of my AquaDrive installation either after all the work I put into it but I didn't have a nice digital camera then.
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Old 11-08-2012, 11:03 AM   #15
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No, not yours, I was talking about another one that failed quickly and with great enthusiasm.

There are photos on the site somewhere ...

A properly installed Cardan shaft is a common means to transfer power between a marine diesel and the propeller shaft. Particularly with the advent of Z drives and such.

They just have to be engineered correctly and installed with quality parts by competent technicians.
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Old 11-08-2012, 11:18 AM   #16
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To my knowledge all Pilgrim 40’s are equipped with an Aqua Drive system. No problems here with mine.
http://www.aquadriveusa.com/system/system.htm
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Old 11-08-2012, 12:26 PM   #17
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Quote:
Originally Posted by RickB View Post
I can't believe the one person here who has one hasn't posted a photo of his U-joint drive ... or commented on its performance.

Nor can I.

Mark! Where are you?
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Old 11-08-2012, 10:27 PM   #18
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I Am Soooo Glad:

My Tolly simply has a very well aligned group of good ol firm/rigid engine mounts, strong BW tranies, good cutlass bearings, well tuned props, true shafts, and smooth running gassers. We experience no vibration at any speed. With engines synchronized to matching rpm I relish the sweet tune they collectively sing! Sorry, neither pict clearly shows shaft connect area.

Old-School ways can work great, be easy to keep up, and stay darn economical too!

Others with simple Old-School driveline set ups... chime in!
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Old 11-08-2012, 10:29 PM   #19
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John,
That's the AD I had. The smallest w only two bolt ears to mount the thrust bearing. I think I'd get the next size up just to get more mounting ears. Alignment is very difficult w only 2 ears. AD is a quality product other than that. And I'd say the Pilgrim must be a quality product to offer the AD on their boats.
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Old 11-08-2012, 11:07 PM   #20
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Greetings,
Mr. Art. Old school here...24X16 four blade wheels, strut c/w cutlass bearing, aprox 10'X1-3/4" shafts, conventional stuffing box c/w goretex, that hard rubber/plastic hockey puck piece Mr. manyboats alluded to (orange color), flanges aligned to within .003", velvet drive and then Amos and Andy the Lehmans. No vibrations....
Stuffing box usually runs luke warm. Works for me.....about 4gph @ 7-8 knots (1650 rpm) to the best of my VERY poor memory. Seems to be propped OK as I can run up to 2400 RPM WOT....I get scared @ WOT....WAAAYYYY to fast!!!!!!!
Oh, and mounts??? There's some rubber in there so soft mounts????
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