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Confusion; Main Crankshaft Bearing Classifications

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    Confusion; Main Crankshaft Bearing Classifications

    Hello all! :D many a question about all of this bearing stuff. I'm rebuilding a m20b25. 87 model year.

    My engine parts are in the machine shop. my engine had the red paint dots on it before the machining, so this means it had the "red" crankshaft bearings, correct?

    the table in the bentley lists as follows:



    Specification

    Main bearing journal diameter

    Standard (nominal diameter 60mm)

    red: 59.98-59.99mm
    blue:59.971-59.980
    yellow:59.984-59.990
    green:59.977-59.983
    white:59.971-59.976



    The dude at the machine shop gave me my main journal size of 2.3612" (59.9745mm). This would put me in the "blue" bearing classification, correct? he told me to get the "standard" ones. idk why. i'm new at this rebuilding game. either way, I can NOT seem to find red or blue sized main bearings anywhere! even in the realoem catalogue, the only sizes listed are yellow, green, and white. I would like to get OEM bearings if possible. but if my engine calls for either blue or red bearings, i don't want to have to grind my crank smaller or something?

    is this a publication error in the bentley? why would there only be three bearing sizes in the catalog when the bentley lists 5?

    I had my crank journals polished. the measurement i got was for after the polishing. should this change my bearing size at all?


    So, summary: what color main bearing should i use? and why? Where can I find this correct size?

    ty! :)
    '87 325is [because racecar]
    '81 Kawasaki KZ550 LTD {summer dd}
    '97 Subaru Legacy Outback Limited (winter dd)

    #2
    uhh, in the aftermarket, you'd buy the 'standard' bearing, and have .0026" oil clearance, end of story.

    You can also use the white, unless I'm really reading this wrong.
    Bentley has a lot of minor mistakes and a few wretched errors- I wouldn't trust it entirely in this matter.
    I WOULD measure the clearance with the new bearings before final assembly...

    t
    now, sometimes I just mess with people. It's more entertaining that way. george graves

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