Babbitt Bearings Revisited

Hi FrankBird, without inspecting the set up closely. I figure you have one of two setups. First setup, the babbitt bearing you are trying to refer to, looks like a bronze or brass sleeve. I think your missing a seal assembly in the housing if this is the case. The hole would be for a zert to pump grease into this area between the two seals. Second setup, would be a brass or bronze sleeve, exposed to the elements and the hole would be for fluid ingress to cool the area of the shaft and sleeve. This sleeve should be changed at least once a season when the boat is pulled out for normal look over. The fit on this should have a clearance of .002", so when you wiggle the shaft will have a total reading of 0.004" The sleeves are inexpensive and are a standard stock item in sizes. You might have to do a little filing for fit.

After you scrap away the insides and install new items, be sure to have the whole assembly laser aligned, from the transmission right to where the shaft goes in the rear housing. It will save lots of wear and tear on bearings and sleeves.

Best of luck and happy fishing/sailing/tanning.

First setup, the Babbitt bearing you are trying to refer to, looks like a bronze or brass sleeve.

Whoa up there, excuse me, bronze or brass sleeves can not be substituted for journals designed to be filled with Babbitt. Back pedal about sixty years.

The hole would be for a zert to pump grease into this area between the two seals. Second setup, would be a brass or bronze sleeve, exposed to the elements and the hole would be for fluid ingress to cool the area of the shaft and sleeve.

The hole would be to relieve pressure caused as the oil float type lube system gets warm. The seals would be wood or leather.

This sleeve should be changed at least once a season when the boat is pulled out for normal look over. The fit on this should have a clearance of .002", so when you wiggle the shaft will have a total reading of 0.004" The sleeves are inexpensive and are a standard stock item in sizes. You might have to do a little filing for fit.

Babbitt bearings should last several years of heavy use. Many years have passed and I do not remember the spec's but the clearance I seem to recall is about .015" .

Thanks guys, I think. I feel I'm not any further ahead in my quest. The shaft entry point as you see it has always had this appearance, the thick coating is Coal Tar epoxy that I use on the entire hulll below the waterline so I don't think a seal is missing unless it came off four years ago.

FrankBird, you are further ahead, just by asking. I like when I'm quoted.

Any way, babbitt bearings require a load area with an oil wedge to reduce friction between the metal parts. In this case we are dealing with something that has little radial load < 10% and 90% trust at speed. Gravity would cause the shaft to sit in the bottom half of the sleeve during slow revolutions. When you get up to speed the shaft would then center itself from the mechanical seal, pillow block and transmission. Hence the noise at slow speed and then clearing up when you are at higher rpm. This the reason I'm saying sleeve, it has a very light load on it.

I think the seal is missing as I can see a possible landing for it. The indent is just before the area where the sleeve would be found. Scrap away the paint in this area, if it has a flat bottom and parallel walls it could have had a seal in this area. We are not talking of a large mechanical seal, just a small one to keep weeds and sand out.

By the way nice boat, give us a side shot.

Thanks Mayt2u,

I will clean out around the area you've indicated, it looks as if I have to pull the shaft anyway. The noise I described just started this past summer (mid July) initially I attributed it to the damage to the prop (we struck a piece of steel girder in shallow water and curled the tips somewhat)

Here's a pic

Babbitt bearings? How old is that boat? I am not familiar with marine things but the last time I saw babbitt bearings was on my first car a 1936 Chevy.

I thought babbitt had gone out not too many years after.

Is that boat a one off or a production item. Are there technical data, drawings, available from a manufacturer? Have you checked for such on the web?

The pictures don't say too much to me but it seems you ought to be able to pull out whatever is there by way of bearing and assemble from stock appropriate bearings and seals to do the job.

I have some experience with reconstruction of old machinery long out of production; printing presses. We were always, at least, able to take a catalog gear or bearing, sometimes deliberately selecting something oversize for excess metal, and then have a machine shop cut, key, or bore down to appropriate size.

If you do not have the skills to do that for yourself, at least to be able to measure and specify, I would look for a machinist to look at the problem and let him craft an answer.

Preferably an old machinist with German or Swiss training. Amazing what they can do with a file and a scraper, which incidentally were the tools used to final fit babbitt bearings.

j.

Jack, you must have missed the last 100 years. It is now the year 2008. Babbitt bearings are widely used. Turbine engines are a big user. The other are any fast moving shafts that roller bearings can't keep up to. All of your car engines use babbitt bearings. Mr Jack I like a good fight, but hate to combat with someone COMPLETELY unarmed. CHEERS!!

maytu,

Perhaps that is so. I was thinking of poured in place rod bearings. But you are right. I have not looked at the innards of a car engine in many a year.

Nonetheless, I still think my advice to our boating friend is appropriate as a means of solving his particular problem.

j.

Ah but boats are far less forgiving than printing presses, maybe take the machinist boating too.

Excellent link.

On a US Navy repair ship we poured the molten mixture into the bearing blocks then mounted on the half shell on a turret lathe and carefully machined, sometimes good adhesion was lacking and the pour or part of it would fly off. A scatter shield is recommended.

I should thoroughly reacquaint myself with this procedure thanks.

Wow, nice boat!! A friend of mine says "Go down and fix it for a ride". So where do you live so I can have a closer look and then HAVE to take it for a test fishing ride, I meant test run. I can do the alignment and balance part. We are thinking of going to Mexico in the next little while any who. Cheers. Robert

mayt2u, et al

Thank you all for your interesting, informative and lively input. With your combined input and a bit of research I have narrowed it down to two options: Have the bearing repoured (which can be done insitu without pulling the shaft) or pressure fit rubber bearings. The jury is still out and it will probably come down to cost, risk and availability of someone to do the pour. The boat is on a fixed launch date so time is also a critical factor. Mayt2u if you can make it down and get it poured before 03 May; you're on and you can have that test run. Everyone else thank you again, your directions and insight have been invaluable.

By the way if anyone wants to see some more photos or video footage check out www.proteusdiving.com (sorry, link no longer available)

If you're going to retrofit I'd suggest to pull the shaft do it right is much better than being dead in the water. I suggest replace Babbitt with graphite impregnated nylon rather than rubber.

Fair winds and following seas...