squeaky reduction gears video

[lat 64]

Hi all,
I have a mysterious Shaft noise that I have been writing about on this forum,
now I have figured out how to post a video on Google Videos.
Just to review the problem:
(1) It is not there in neutral
(2) It is there in both forward and reverse
(3) Shaft and all gear boxes run nice and cool
(4) Pronounced vibration at aft end of engine/reduction gear assembly but not so much in the front(out of alignment?)
This noise is not a normal noise, it is loud and drives me nuts.

here's the link to the video:

http://video.google.com/videoplay?docid=7955666663891380112&hl=en

i will check to make sure this link works
(update; yep it works, about 450 k)
Russ

[Don Moyer]

Russ,

Great audio! However, I'm not sure where to imagine my ear as being. If I'm leaning over the back of the engine, I can envision a major thrust bearing failure in the gear reduction bell housing assembly, although on your 2 to 1 gear reduction unit, the thrust bearing is actually two bearings side by side and each bearing is twice the size of the direct drive thrust bearing. In other words, these bearings could (without much exaggeration) be used on a railroad car wheel. I've never seen one of these bearings fail in all the years we've been focused on the Atomic 4 fleet.

If the noise is transferring to the cockpit (as the video rather suggests), I can sort of imagine a cutlass bearing coming apart.

Did the noise show up all at once (as after some kind of maintenance action) or slowly over time?

Don

[Administrator]

Now THAT is an avatar!

Way to go!

Bill

[sastanley]

Yeah..but was that picture for his avatar taken at latitude 64!!??

Guess I gotta go listen to the video to be a valid contributor to this thread.

WOW...that is loud and weird...I am a newbie so I have nothing useful.

[jhwelch]

It's easy to check your alignment--take the 3 bolts out that hold your
coupling to the engine and see how they line up. In addition to vibrations
bad alignment will also cause your cutless bearing to wear out prematurely.

-jonathan

[lat 64]

Thanks everyone for the interest.

Yes, I was standing in the cockpit right above the engine. The noise was there when I bought the boat this summer and the PO said it had been there for some time. I wish it had been just after some maintenance. The talk about cutlass bearings scares me a little because I think I would have to put the boat on the grid and do it in a hurry.*
We’ll just have to wait until after Christmas when I pull the whole thing out. I'll document the whole thing then.

The Avatar pic is on the beach in Monterosso al Mare, Italy part of the Cinque Terre. Sigh.

Russ


* We have extreme tides in Homer and the boat can be placed on the grid ($40.00 per tide) and worked on when she goes dry.

[lat 64]

Sometimes you feel like a nut, sometimes you don't

Well, I got the reduction gear case apart and some things look good and some things look.. well... weird! Some real Miami CSI analysis to do. Here are two pics of the problem as I see it.

First the two broken bolts that you see sitting on top of the small gear came from the two holes just behind.
And now the big one: Don’t we need a big nut to keep this gear from working it’s way off the shaft, just as it has done!
And does anyone know if this might cause the bolts to break?

In the close-up you can see the marks from the outside gear as it started to rub on the back flange of the small gear.
Don’s first call was VERY close,(about one inch to be precise).
The good news is if this is the problem, I can fix it easily. Do you have a part(nut) to fix this Don? The gears look fine and the bearings are quiet and tight. All the reversing gear stuff looks good too. I am pleased and at the same time amazed. I think I caught all of the bad stuff on this engine just in time.

I’ll be making a parts list soon, and calling in for backup.
Now, where did I park the Hummer?


Russ

[Don Moyer]

Russ,

I'll have to check into the official size of that nut and get back to you.

Don

[Don Moyer]

Russ,

It turns out that this is a special low profile flanged and slotted castle nut for 3/4-16 threads. We've been unable to find a new nut with these specifications, but we'll have a used one waiting for you at our warehouse which you can add to whatever other parts you may need. You'll have to place your order with Ken at (610) 421-4436 since the nut does not appear in our online catalog.

Don

[lat 64]

missing nut

Don, I will certainly order that nut too.
I love a picture for what it tells me, and I found a private web page by another Columbia 36 owner .
He has an old Atomic-4 parts list scanned and put up on his site.
This was very useful for me to see the three pages with exploded drawings of the reversing gear, v-drive and reduction gear assemblies. I have taped them into my dog-eared MMI service manual. It is starting to look like my mothers old cook book.
Here is the url:

http://www.geocities.com/unifield/indexparts.html

looking forward to calling in and talking to Ken after I mic everything,

Russ

[s/v Dearbhail]

I'm glad Don tracked that down for you. I have an A4 parts catalogue but the entire file won't upload. The file is 2.22M. I don't remember where I down loaded it from.

The 3/4X16 nut is part number 263761
The two bolts with the sheared head should be cap screws, 5/16-18X1, part number 231059

This link may be used to down load the A4 parts list, owners manual and maintenance manual. Makes a great supplement to Don's manual.

http://www.user.firstclass.com/~Eric/Arioso/Manuals/Atomic%204%20Engine/

[lat 64]

manuals

Thanks for the link. I just now got'em, every one.
I glanced at them and already the graphics have told me much. Someone has put a bit of labor into electronifying them.
Much thanks to Eric.
later

Russ

[lat 64]

new parts on order

I looked up that nut and it's actually part # 287372. The part #263761 is for direct drive coupling. No matter, Ken says he put out an APB on the thing and the warehouse crew found one. He says they are rare so I think I am lucky.
Any reduction gear people out there—save those old parts!

ciao,
Russ

[s/v Dearbhail]

Russ,
I'm glad they could help. I have a direct drive, late model A4 and forget there are other versions out there.

[67c&ccorv]

Not trying to be funny (really!)...but where did that nut go?

Not lying somewhere in the bottom of the gearbox or something?