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F134 crank polishing

Discussion in 'Early CJ5 and CJ6 Tech' started by atuomi, Nov 30, 2012.

  1. Nov 30, 2012
    atuomi

    atuomi rookie

    Smithers, BC, Canada
    Joined:
    May 16, 2006
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    34
    Hi, I've got a question for the engine machinist's out there.

    My F134 spun the #1 rod bearing due to oil starvation a while ago and I'm finally getting around to fixing it. The bearing surface on the crank looks ok, it just seems like the soft bearing material is smeared onto it. I am hoping that it can just be polished off. If it is damaged and it needs to be ground undersize, can I just get the one journal done or is it common practice to get all 4 done the same size?

    Thanks

    Austin
     
    atuomi, Nov 30, 2012
    #1
  2. Nov 30, 2012
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
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    Nov 6, 2002
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    The crank needs to go to a machine shop, who can determine what needs to be done. If it needs to be cut undersized, there is no reason to cut one journal and not cut the others. In fact, I doubt that any reputable shop would do that.

    This is one of the most important components of the engine, don't Mickey-mouse it trying to save 20 bucks. Do it right.
     
    w3srl, Nov 30, 2012
    #2
  3. Nov 30, 2012
    tarry99

    tarry99 Member

    Northern California
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    Sometimes they can take a tenth or two off and it will clean up..............but keep in mind that journal will now be a little undersized ( more clearance) and if for some reason you still have an oil problem this may make it even worst. Let your machinist tell you whats best. If he says grind them then do the other 2 since I believe two share the same journal .........nothing worst than having mismatched bearings in a motor , notwithstanding once you cut the one journal down the balance of the crank is gone. Fix your oil problem!
     
    tarry99, Nov 30, 2012
    #3
  4. Nov 30, 2012
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Try some crocus cloth to remove the transferred bearing material. It's a forged steel crank, and it will withstand quite a lot of abuse before the steel is damaged.

    I would clean off the bearing material and then measure the journal to see if it's still within spec.
     
    timgr, Nov 30, 2012
    #4
  5. Nov 30, 2012
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Before tearing the whole motor down, clean the crank up then check with micrometer or plastigage. While I agree not to cut corners, it used to be common to put in bearings .001" or .002" undersize on tired journals, if necessary, without machining.
     
    PeteL, Nov 30, 2012
    #5
  6. Nov 30, 2012
    atuomi

    atuomi rookie

    Smithers, BC, Canada
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    Upon further disassembly, I discovered that there is no bolt/washer holding the phenolic gear onto the cam... Nice. Looks like its still sitting in the right spot, wonder how long its been spinning around in there like that for.
     
    atuomi, Nov 30, 2012
    #6
  7. Dec 4, 2012
    atuomi

    atuomi rookie

    Smithers, BC, Canada
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    Measuring up the bearings and it doesn't look good. The one that spun is quite out of round. Measuring 1.885" in one direction and 1.908" 90 degrees apart. My chilton book says original bearing size is 1.9375". I haven't seen any bearings that are greater than .040" undersize so I think the crank is done. Can anyone confirm that 1.9375 is in fact the original measurement of a new crank?
     
    atuomi, Dec 4, 2012
    #7
  8. Dec 4, 2012
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
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    You might be able to either get a new crank kit with a reconditioned crankshaft, or have that one re-welded and reground. Check with a good machine shop before you spend any money, it may save you money and time in the end!
     
    w3srl, Dec 4, 2012
    #8
  9. Dec 4, 2012
    tomtom

    tomtom Sponsor

    Huntington Beach, CA
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    tomtom, Dec 4, 2012
    #9
  10. Dec 4, 2012
    atuomi

    atuomi rookie

    Smithers, BC, Canada
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    Thanks, hadn't seen those ones, I should be ok to regrind if I can those.
     
    atuomi, Dec 4, 2012
    #10
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