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PostPosted: Thu Dec 06, 2012 12:29 pm 
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Got mymain bearings for my stroker build and one bearing showed signs of the other in the box hitting it. Took them to jims custom vw, he hit it with emery cloth said good to go. An said they should all be hit lightly . Just wondering info, opinions on this before I use these bearings

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PostPosted: Thu Dec 06, 2012 1:08 pm 
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I would take 'em back for sure!

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PostPosted: Thu Dec 06, 2012 2:58 pm 
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No chance.

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PostPosted: Thu Dec 06, 2012 8:20 pm 
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Ewwwwwwww :!: :!: beware

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PostPosted: Thu Dec 06, 2012 8:53 pm 
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I always polish the mains with a very fine sand paper, I cant remember the grit number but it feels almost like a peice of paper. I have had the coating on the bearing have bad places before and polished them out with no problems. 8)


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PostPosted: Thu Dec 06, 2012 9:13 pm 
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I have seen this done before and the motors ran fine,but that's not saying I would want to try it personally.Chad :mrgreen:

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PostPosted: Thu Dec 06, 2012 9:29 pm 
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Just so ya know. Everywhere I have ever worked doing machine work, you were expressly prohibited to use any emery cloth or sand paper on a babbit bearing. The reason is that babbit is real real soft and when you are sanding it you are also imbedding the abrasive of the paper into the babbit. With the abrasive imbedded in it could play hell on the finish of a brand new crank. Some of the old timers use crocus cloth to clean them up but to me it was the same as using emery.

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PostPosted: Thu Dec 06, 2012 10:57 pm 
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The only media i would even consider using on those is scotch bright. Where you at Roy. We need the pros thoughts.

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PostPosted: Thu Dec 06, 2012 10:59 pm 
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i'm with Mike,I would never use any kind of sandpaper but have used fine scotchbrite pads with oil on them to polish bearings for years. I would make sure the bearing is clean and run it.


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PostPosted: Thu Dec 06, 2012 11:29 pm 
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Arighty then, a Pro showed up lol. :wink: :mrgreen:

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PostPosted: Fri Dec 07, 2012 7:38 am 
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Emery cloth, definitely NO. Scotchbrite is what we used on the bearings in the funny car. After every pass we would pull out all the bearings and measure them. The ones that passed were de-burred and polished with scotchbrite.

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PostPosted: Fri Dec 07, 2012 7:50 am 
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You can damn near see the scratches when you run your finger across them let alone a piece of Emery cloth!! Imbedded particles I would say so. I was always told spray off with brake clean and try not to touch the surface where the crank rides??? GET NEW ONES!! just my opinion. :wink:

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PostPosted: Fri Dec 07, 2012 3:03 pm 
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Its not like there was deep marks in these bearings, when you polish one up it shines compared to the dull look directly outta the box, you couldnt feel these marks i seen at all. And after reading a post on the samba about main bearings etc... they will all get hit with scotch brite and be used. Not worried about them at all.

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PostPosted: Fri Dec 07, 2012 9:21 pm 
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The paper I use is the same stuff you would use to wet sand, its not a course as a scotch brite pad.


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PostPosted: Fri Dec 07, 2012 11:48 pm 
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http://www.thesamba.com/vw/forum/archiv ... 276--.html

This is the post Ive been reading over.

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PostPosted: Sat Dec 08, 2012 12:05 am 
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http://www.yellowbullet.com/forum/showt ... 007&page=2

These guys are saying they use wd-40 and brown paper bag to polish up the bearings, No grit from anything that way. Sounds better to me lol

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PostPosted: Fri Aug 28, 2015 6:35 am 
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Hand "polishing" creates valleys
and peaks almost every time that
it is used. My mechanic friend will
spend 8 hours "polishing" crank journals
for his race engines. I often wonder
why it takes so long.
While he IS creating a very smooth
surface, he is also creating a non-
round condition that seems counter-
productive.


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PostPosted: Wed Sep 02, 2015 8:47 am 
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I'm with Mike on this one, even if we are dragging dead threads up this week :D
No way does abrasive grit go near babbit surfaces, it'll embed.
And that doesn't matter whether it's sandpaper, wet and dry, or scotchbrite, it's all loaded with abrasive particles.

The only thing that might ever be used is a smooth ceramic hone with oil to burnish the surface and make sure there's no small burrs.


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PostPosted: Fri Sep 04, 2015 9:09 am 
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I never see any reason for EVER
disturbing a bearing surface. Follow
the simple steps and you are golden:
1) Measure measure measure. Buy
or borrow the measuring tools and
calibrate the measuring tools with
the right standards.
2) Mathematics. Do the math. The
stack of numbers is easy. Take the
engine block bore diameter and subtract
the thickness of the bearing (twice).
The number that you get should equal
the diameter of the crank journal added
to the clearance that you want.
3) If the clearance is correct, install the crank
and lubed bearings and torque the case bolts to
spec.. The crank should rotate freely. If
not, something has to go back to the machine shop.
4) The same thing applies to rod bearings.
Do the math and check for free movement.


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