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Antique Engine Archives All archived posts from 1999 to 2004 when SmokStak was on EnginAds. This is a read-only board.

Antique Engine Archives

Replacing Babbit for main bearings


this thread has 21 replies and has been viewed 31481 times

 
 
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  #1  
Old 01-27-2002, 12:17 PM
Bob Johnson
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Default Replacing Babbit for main bearings

I am wanting to try to replace the babbit main bearings for my 1 #/$ HP Associated air cooled engine. My plan is : make a mandrel slightly undersize to reach acrossed both main bearings and extend out passsed the block 1" on both sides. I will need a baseplate and two supports to bolt to each end of the mandrel to hold it in place. I want to make two metal covers to act as a dam on the inside of the block mounted around the Mandrel to hold the babbit in. I would then fasten all together and lay the block on its side with support under to make level. I would pour each bearing seperately aand then remove the bearing caps and remove the mandrel. From there it would be scraping to seat the crankshaft into the bearings. What might I be doing wrong or might there be some way to do it better from some one who has done This? Thank you all
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  #2  
Old 01-27-2002, 12:24 PM
Bill Hazzard
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Default Re: Replacing Babbit for main bearings

Sounds like a good way of doing the job to me. I have found that the babbit shrinks some and makes the bore slightly under size so I use a mandrel of the same size of the shaft and I still have to scrape some.
  #3  
Old 01-27-2002, 12:56 PM
Kid Dynamo
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Default Re: Replacing Babbit for main bearings

You should shim the caps apart, but I'm not the guy to say how. Kid D
  #4  
Old 01-27-2002, 01:12 PM
John Hammink
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Default Re: Replacing Babbit for main bearings

Bob,Harry Terpstra an engine friend of me made an interesting setup for pouring new bearings in his Sparta engine. The pipe he used is of stainless steel, it doesn't stick to babbit he said. Take a look at the page, maybe it's of your help. And if you be there, see the rest of his home page, it's worth your time. Regards, John H. in Holland.

j.g.hammink@quicknet.nl mail bounces


Pouring bearings.
  #5  
Old 01-27-2002, 01:23 PM
Al Hettich
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Default Re: Replacing Babbit for main bearings

You must shim the caps apart. Apiece of 10 or 12 ga. sheet metal against the shaft on both sides should do it. I have used wood to make the babbit dams. They are easy to carve, and only smoke the place up a little. The babbit metal cools fairly quickly, but I keep water around just in case. I drill a sprue in one side and the riser in the other. Cut a notch in the ends to allow the metal to fill the bottom and top. When it is cool, chip away the wood and cut the flow channels. You got a brand new 80 year old bearing. Some scraping and fitting and it is something to be proud of. Good luck, and remember if you don't like it do it over again. Have fun Al
  #6  
Old 01-27-2002, 01:33 PM
Al Hettich
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Default Re: Replacing Babbit for main bearings

If you think the babbit is going to stick to your shaft/mandrel, soot it up with your acetelene torch. Nothing will stick to that. Al
  #7  
Old 01-27-2002, 02:29 PM
Ed Kinch
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Default Re: Replacing Babbit for main bearings

Hi Bob,

If you coat the parts you do not want the babbitt to stick on, with a bar of fels naphtha soap it will release easily. Just take a bar of soap and rub it on until well coated. You can also use the soap to make a tinkers damn that the babbitt can not flow past. If you criss cross a string on your shaft where you want grease or oil to flow it will leave the criss cross grooved pattern in the babbitt bearing.Be very careful there is no water present or the babbitt will spatter.

Ed Kinch
  #8  
Old 01-27-2002, 03:04 PM
Kid Dynamo
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Default Re: Replacing Babbit for main bearings

Also- if you have to cast integral thrust flanges in the bearings for crankshaft end play control, more set-up would be needed.
  #9  
Old 01-27-2002, 04:09 PM
Jim Tremble
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Default Re: Replacing Babbit for main bearings

QUESTION----

I have never poured bearings or anything except tons of sinkers for fishing. Is it possible to pour through the grease cup holes in the caps and clean them out after the babbit has set up.

I have to repour an engine at a later date and will be watching this thread closely.

Thanks, Jim
  #10  
Old 01-27-2002, 04:23 PM
Bob Johnson
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Default Re: Replacing Babbit for main bearings

Hi all Have been getting a world of good help here so now the next question, I will be doing about 2HP engine , does anyone have some Idea of how much Babbit I may require to pour this engine? Thanks all for all your help
  #11  
Old 01-27-2002, 06:25 PM
Tom Winland
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Default Re: Replacing Babbit for main bearings

Make sure you have it damned up well. I've poured some bearings on large oilfield engines and babbit will run just like water and will leak out if not sealed up well. It also sets up very fast so once you start pouring don't stop until full.

Tom Winland
  #12  
Old 01-27-2002, 07:52 PM
NICK
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Default Re: Replacing Babbit for main bearings

You can pour from the grease cup hole but where is the air going to vent from? Leave to open spaces either side of top bearing cap, pour the metal in there, air will vent from other hole and cup hole. Be sure the place you pour from is slightly higher than top of bearing so the bearing is filled completely. Also, no one has yet mentioned how the bearing is to be held in place. Usually there are holes drilled for the metal to folw into and keep bearing from rotating. If not either drill some or tin the bearing area with 50/50 solder, use a good flux too. To get any good rusults the bearing area must be CLEAN! Get any oil, grease or crud out of there. Preheat the bearing shell and pour before it gets cold. Whatever/however you pour a bearing be careful and make sure there is no moisture in bearing shell!

Cheers! NICK
  #13  
Old 01-27-2002, 09:44 PM
Jim Tremble
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Default Re: Replacing Babbit for main bearings

Nick,

Thanks. I now see how I have to pour my mains. They are thrust bearings on both ends and I can vent them from the top on both ends. Never used any vent holes on the sinkers.

Thanks, Jim
  #14  
Old 01-27-2002, 11:37 PM
Mike
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Default Re: Replacing Babbit for main bearings

Bob, I would install the piston and connect up the rod bearing to the mandrel to keep it in line with the new bearings.
  #15  
Old 01-28-2002, 01:54 AM
Ben Laughlin
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Default Re: Replacing Babbit for main bearings

Hi Bob, The preheat should be at least 200 degrees with 300 being better. I found that a hollow mandrel is easier to heat. I use auto freeze plugs on each side of a pour to make the thrust areas. The shim needs to go close to the crankshaft and when you are done a hit from a chisel at the parting line will seperate things. It is very important to seal things up well. Everthing must be "water tight", a little moistened fire clay can be pushed against the small cracks. For the larger areas I use stove door gasket cord to surround it. The pouring temperature is hotter than lead. I read somewhere that it is hot enough when a pine stick chars when stirring. Do stir it as it is an alloy and needs to be kept mixed. You may get a weep when pouring, if you have a helper with gloves and a rag they can push against it so you can continue. You can't stop and start again. If you stop before the bearing is full, you tear it down, clean it out and start over. Good luck, Ben
  #16  
Old 01-28-2002, 01:20 PM
Kirk
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Default Re: Replacing Babbit for main bearings

One more tid bit that I don't believe has been addressed yet is to be sure that you remember timing and governor gear clearances when positioning the mandrel.

Kirk
  #17  
Old 01-28-2002, 03:40 PM
Joe
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Default Re: Replacing Babbit for main bearings

I'm missing something . The info I've looked at here and the web page with pictures shows pouring bearings that are in two pieces i.e bearing caps. If the pour is around the mandrel or shaft how do you split it afterwards?
  #18  
Old 01-28-2002, 04:09 PM
Ben
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Default Re: Replacing Babbit for main bearings

Hi Joe, A shim separates the two halves. When you pour you are pouring both halves at the same time. There will be some small areas where they are connected but a hit with a chisel at the parting line will separate things. If you poured the halves separately you are likely to end up with a tapered bore when the bearings are assembled.
  #19  
Old 01-28-2002, 10:43 PM
Vern Barker
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Default Re: Replacing Babbit for main bearings

Hi, Just a few suggestions,If one has use of machine shop you can make a babbit ingo,then machine it to the size and shape of the bearing you need.All that is required is a peice of black pipe saw in half lenght ways heald togeather with hose champs pour solid remove clamps there you are a solid babbit blank chuck in lath and have fun.Just make blank longer ther you need so you can chuck it and turn the o.d. and bore with out removing it.

Try it you 'r like it Vern.
  #20  
Old 01-29-2002, 01:25 AM
Jim Tremble
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Default Re: Replacing Babbit for main bearings

Vern

I like this idea. I can turn the thrust end right with the bearing. AND it seems it would be more accurate than trying to center a mandrel in the block before pouring. One question, What will hold the bearings from spinning ???? Is there a locating pin or something ?? I have never done this and have not taken the babbitt out of a main to see what holds them in place.

Thanks,

Jim
 


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