Bellhousing runout question

Engine, Trans & Driveline

  1. wasco

    wasco Well-Known Member

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    (Please, be kind) - I've set up the dial indicator from scratch a few times now, and I keep getting the same readings. From what I can wrap my head around, it seems I need a set of .021 offset dowel pins. .058 divided by two is .029, leaving .008. I can't figure out how the runout on the opposite axis can both be positive? Shouldn't it be shifted either one way or another, positive or negative, from center? I watched several different YouTube videos on the procedure but I'm wanting to be sure I order the correct pins. I just don't see how the top/bottom can both be positive numbers. This is on a '64 383 with a 2892626 11" bellhousing. I used the pressure plate holes to mount a strip of 1/4" steel across the flywheel so the magnetic mount would be offset, to better center the dial (not enough room to mount the dial with the magnetic mount in the center of the flywheel). Do I just need the .021" offset dowels and try to get all the numbers under .008", as specified in the Mopar assembly manual? I don't think I'm doing this right.

    Screen Shot 2021-04-16 at 6.57.11 PM.png
     
  2. jamie

    jamie Well-Known Member

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    Yep your doing it right, that Bell is really off wow.
     
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    • wasco

      wasco Well-Known Member

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      That’s what I thought! It was so far off I figured I was reading the dial incorrectly or was doing the measurement incorrectly. If you think I can get it close enough with the .021 dowels, I’ll get them ordered. I really didn’t want to have to eat the cost of this bell and buy another.
       
      Last edited: Apr 16, 2021
    • Jeremiah

      Jeremiah FBBO Gold Member FBBO Gold Member

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      I would take measurements between those already taken to make sure there isn't one small area the is way outside the other readings.

      Another way to check for accuracy of your reading is to zero the dial at your point of greatest runout and see if the indication mirrors what you read prior to zeroing it out at the worst spot.
       
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      • 1 Wild R/T

        1 Wild R/T FBBO Gold Member FBBO Gold Member

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        I would grab either a set of calipers or an inside mic & measure that bore on both axis'... By those numbers it seems like it's out of round.....
         
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        • Mopar Miki

          Mopar Miki New Member

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          Finally...some one installing a bellhouse the correct way.
          Everyone pay attention now.
          Make sure both mating surfaces are super clean with no paint etc
          Install every bolt and torque to spec. Be sure the threads have assy lube on them.
          I use studs not bolts. Much better results.
          Be sure the BH is repeating the runout deviation by removing and reinstalling it at least 3x. Repeats the measurement to the number within +/- 0.0005 inches. 0.000000 is better.
          Install whatever offset dowls the calculation calls for
          Repeat measurement
          Make 12 o'clock the zero position
          Then make your diagram. That will show the axis of alignment of the BH so you can align the dowels with that line
          If you don't like your new measurements you can move the clocking a bit to see if it improves
          You need to be CLOSE to zero as possible as it affects overall performance, wear, noise, shifting esp going into 1st when rolling up to a stop. 0.005 is a lot in my world of 4 speed
          0.0025 max, 0.00050 is best

          The back of the bh needs to be checked for squareness to the center-line of the crank. This is important. 0.0000 is the spec. The amount of torque on the 2 lower large diameter studs or bolts does affect the squareness. Some times the bh needs shimmed at those bolts/studs to make it square.

          Be sure the transmission bolts to the bh before you install it in the car.
          Use the roller pilot bearing.
          Do not drive without the metal bottom cover installed correctly.
          Advice is only useful when you follow it
           
          Last edited: Apr 17, 2021
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          • 493 Mike

            493 Mike FBBO Gold Member FBBO Gold Member

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            Did you check the fly wheel for runout? It may be bent/warped or the crank flange could be also, throwing off your concentricity readings. I recommend adjustable dowels from: RobbMcPerformance Bellhousing Alignment Dowels
            Mike
             
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            • zyzzyx

              zyzzyx FBBO Gold Member FBBO Gold Member

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              Take your 0.019 & 0.033 numbers and move them to read 0.014. set those readings @ "0".
              Now split your 0.058 reading to 0.029. & 0.029.
               
            • wasco

              wasco Well-Known Member

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              The bell opening checks out - 4 13/16 all around. And as far as the runout on the flywheel, I’d hope it’s fine since it’s a new part (Jegs 601400) but I guess you never know. I’ll see if I can set up the dial on the block to check that.
               
            • Cranky

              Cranky Banned Staff Member FBBO Gold Member

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              Space craft isn't held to those kinds of specs!! Dang man.....:D
               
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              • 70chall440

                70chall440 FBBO Gold Member FBBO Gold Member

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                I am not sure what has happened but I put a lot of 4 speeds in a lot of vehicles and never once ever checked run out, mainly because I never thought about it or knew about it, but I never had any issues either. I am not saying that it doesn't need to be done as obviously it does at least on some but it seems odd that Me and my buddies were able to do this many times without issue. Perhaps it was because the cars were not as old back then and we were using factory parts or something.
                 
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                • 1 Wild R/T

                  1 Wild R/T FBBO Gold Member FBBO Gold Member

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                  Yeah.. sixth decimal (Millionth of an inch) on a bell housing with a bore that was measured with a tape measure... Good luck with that...
                   
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                  • dadsbee

                    dadsbee FBBO Gold Member FBBO Gold Member

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                    5 ten thousandths on a Mopar... :fool:
                     
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                    • 65wgn440

                      65wgn440 Well-Known Member

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                      The word "overkill" comes to mind. I had a customer come in once that was looking for torque specs for fender, hood, trunk lid, etc, bolts for an old Ford pick-up. Father and son project that has been delayed going back together for three weeks while Dad looked for those specs. He was determined to show son "the right way" to assemble a vehicle.
                       
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                      • dadsbee

                        dadsbee FBBO Gold Member FBBO Gold Member

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                        1000's of 383's and 440's on the Chrysler assembly floor ready for install, with not a single bell housing checked for location since the final casting mould was approved...
                         
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                        • Cranky

                          Cranky Banned Staff Member FBBO Gold Member

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                          There were some warranty issues for gross misalignment in drive lines. Thing is, most of the time that techs were dealing with stuff that was messing up due to misalignment issues, it would just get R&R'd in most cases. My dad had a 69 New Yucker that kept wasting rear bearings, the transmission went out during the first year and numerous other problems. A tech in the shop (remember when we could go out into the shop back then??) mentioned that it's possible the car was cinched down too tight on the rail car. Who knows....but it's still a good idea to check run outs on stuff like bell housings etc. I've found abnormal wear patterns before in automatics before that pointed at misalignment problems. Checking the internal fits and run outs on an auto trans case is a good idea too but going for .0 tolerance isn't going to happen with this stuff. You also need a good rigid indicator set up too if you don't want to deal with 'indicator sag'. The larger the shaft for mounting the dial indicator, the better.
                           
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                          • dadsbee

                            dadsbee FBBO Gold Member FBBO Gold Member

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                            That's what she said..
                             
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                            • Cranky

                              Cranky Banned Staff Member FBBO Gold Member

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                              Was her mouth full when she said it?
                               
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                              • Fran Blacker

                                Fran Blacker FBBO Gold Member FBBO Gold Member

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                                A factory bellhousing you could take a chance a scattershield no way. I'd check factory housing, why take a chance.
                                 
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                                • steve from staten island

                                  steve from staten island FBBO Gold Member FBBO Gold Member

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                                  Exactly what I was thinking when I recently did a 4 speed conversion on my 69
                                  Through the years I also removed and re installed more than a few 4 speed trans and never checked runout but those cars weren't Mopars
                                  My 4 speed bell housing fit very tight on the dowels and when I did the runout it was spot on, maybe I got lucky
                                   
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