Thread: Insert bearings
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Old 02-01-2017, 09:23 AM   #15
BRENT in 10-uh-C
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Default Re: Insert bearings

Quote:
Originally Posted by Jon View Post
So my take from this is if the inserts need to be fit by machining then the advantage of having inserts so they can be changed out quickly just got thrown out the window.
That has always been a sales pitch used by the ones who were promoting inserts, but generally what I have seen is the crank journal pin is worn/scratched when the inserts are worn-out where the crankshaft really needs to be machined again. Where this has the potential to be troublesome is the inserts only come in nominal sizes (Std., 0,010", 0.020", 0.030", 0.040") so if the crankshaft journal pin is worn 0.0025", the crankshaft would need to be removed and machined to the next undersize, whereas a babbitted bearing can have the crankshaft machined to 0.003" undersize and the new babbitt machined to fit the journal pin diameter. Another way to say this using the above scenario is, you potentially have the ability to machine the crankshaft 3 times with babbitt vs. 1 time with the inserts. (.003" x 3 = 0.009" vs 0.010" with the inserts)
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