Modifications to oil passages in A727

Engine, Trans & Driveline

  1. Shade Tree Mech

    Shade Tree Mech Active Member

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    I have seen videos of trans builders indicating that the small oil passages can be opened up a bit to allow for better oil flow. Specifically, the passages for the sun gear bushings and the planetary gears. Will a minor change in these cause a reduced pressure in other needed areas? Could flow reduction in other areas be compensated for by increasing the size of the oil input holes?
     
  2. 69 Sleeper Bee

    69 Sleeper Bee Well-Known Member

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    The only time I ever did anything like that was when putting in a shift kit and following the instructions.
    You should probably be a transmission expert to get into drilling out passages.
     
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    • 493 Mike

      493 Mike FBBO Gold Member FBBO Gold Member

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      I never have done that except in the A-518 model (had to but a carbide drill) output shaft. Now I will say that John Cope recommended a 1/16" hole in the cooler return passage (under the governor support) to send extra lube to the sprag assy.
      Mike
       
    • Shade Tree Mech

      Shade Tree Mech Active Member

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      Would this be a new hole, or an enlargement of an existing hole? Would this be applicable to the A727?
       
    • Dipstick

      Dipstick Well-Known Member

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      It's a new hole, 727 shown. Spraglube front.jpg Spraglube rear.jpg
       
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      • Shade Tree Mech

        Shade Tree Mech Active Member

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        Thanks for the pics. I'll do some more research. Just my luck to drill it in the wrong place. It looks like it's where the inner race bears on the case.
         
        Last edited: Jul 22, 2021
      • 493 Mike

        493 Mike FBBO Gold Member FBBO Gold Member

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        Yes it is new and I should have clarified in my first post that the hole is for the 727 but, may be applicable to the 518 as well as 904s.
        Mike
         
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