SPECS ON PILOT BUSHING, CRANK PILOT HOLE ID AND INPUT SHAFT

Discussion in 'Manual Transmission & Clutch Discussions' started by Franko, Feb 28, 2018.

  1. Franko

    Franko FABO Gold Member FABO Gold Member

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    Does anybody know if there are published Chrysler specs on the pilot bushing ID, OD and installed ID? Also the crankshaft pilot hole ID and an Input Shaft OD? I may have my 340 crank rebushed.

    I know the Brewer Website states some specs on their pilot bushings, but I wouldn't mind verifying them. I'd rather not go with the pilot bearing.

    Or if anybody knows a crankshaft machinist in the know, that wouldn't mind a call.

    Thank you.
     
  2. jos51700

    jos51700 Well-Known Member

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    Have it rebushed?

    Pack it with grease, pound a bolt or closed fitting rod in to drive it back out, slam the new one in using a socket that won't get stuck in the hole, and get on with your life.

    The factory bushing is oilite. The tolerances on such parts are virtually non-existent. Look it up by number and go.
    Make sure you get the one for a factory stickshift crank if that is what you have. if not and you're adding the rowing machine, go with the bearing.

    No crank machinist is ever needed for this unless you're converting. It is literally a ten minute job once the clutch is out.

    The bushing will shrink considerably upon install. Let me know if you can't find them.
     
  3. 67Dart273

    67Dart273 Well-Known Member

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    "In the days" when Dorman and other actual parts manufacturers actually made and sold parts.....instead of importing them from the T.I. Whan company, their catalogs would very likely have had that information. Might look around for an "old shop" which might have some old catalogs.
     
  4. Max1196

    Max1196 Well-Known Member

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    There no pretty prize, just a thing to do the job! 100_1533.JPG
     
  5. Franko

    Franko FABO Gold Member FABO Gold Member

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    I'm sorry, I didn't make something clear. Rebushed was the term used by a crank regrinder that didn't know the specs. It doesn't mean the pilot bushing. This crank may have been an automatic crank that was drilled larger improperly. It is slightly large and out of round. So a machinist told me he could drill the hole larger and rebush it. I wanted to know the specs to do this and to know how much crush a new bushing (metal, I assume) to make it to stay put and then what to drill that out to, so the pilot bushing has the proper crush. Also I have another 340 crank that I installed a pilot bushing in, but the input shaft is very tight. There seems to be only .001" clearance.
     
  6. 4spdragtop

    4spdragtop FABO Gold Member FABO Gold Member

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    Same as what my machinist installed
    20180120_185036.jpg
     
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    • jos51700

      jos51700 Well-Known Member

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      I found a bushing shrink calculator at oilite.com that will tell you what od you need to make sure that your id falls in the range you need after it crushes on install. You can't reliably machine oilite, it tends to close up the pores, so it's better to avoid shrinking it too much and reaming to size.

      That said, are you SURE you don't want the bearing?
      Any particular reason?
       
    • Franko

      Franko FABO Gold Member FABO Gold Member

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      in reading through these Forums, I found that some members had success using the pilot bearing and some members said they failed. I read one post that said when the trans was pulled, the pilot bearing flopped out. It made me wonder if it was previously just hanging on the input shaft. I was also talking to an older engine builder and he said he didn't like pilot bearings because dust may cause them to fail.

      I feel like what Chrysler did originally is best. I still haven't found any documentation on what the crank pilot hole ID should be drilled to. I couldn't figure out that calculator at oilite.com. I called Oilite Tech, but they were no help.
       
    • Daves69

      Daves69 Well-Known Member

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    • jos51700

      jos51700 Well-Known Member

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      Rick Ehrenberg wrote a comprehensive article on the matter in Mopar Action several years ago. Find that back issue or contact him directly from their website.

      I'd be surprised if he didn't have that diameter handy.
       
    • Franko

      Franko FABO Gold Member FABO Gold Member

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      I found one of the Forums (attached below) about Pilot Bearings, that I had read in the past. For whom it may concern: Madscientist said "I despise roller bearings where a pilot bushing SHOULD be. I have had to repair (at the minimum) 15 input shafts that are wrecked from roller bearings."

      Any of us that use forabodiesonly to research certain topics probably find many Mopar Motor Heads that have had good experiences with a certain part or procedure and many Mopar Motor Heads that had bad experiences with same. Sometimes you get the warm fuzzy with one recommendation; other times you don't and you just roll the dice.

      Crank Hole Finish Size For Pilot Bushing
       
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      • jos51700

        jos51700 Well-Known Member

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        8 Bajillion Magnum trucks can't be wrong, but to each his own.
         
      • jos51700

        jos51700 Well-Known Member

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        upload_2018-3-16_22-46-6.png
        I'd reckon that the crank pilot is finish reamed to 15/16+0.001-0.000
        I