727 hard shift from park to reverse

Transmission and Drivetrain Tech

  1. Zak

    Zak Well-Known Member

    Messages:
    57
    Likes Received:
    2
    Joined:
    Jun 3, 2010
    Location:
    Valdosta, Georgia
    Local Time:
    6:00 PM
    727 trans shift harsh from park to reverse. No other abnormalities. Other enthusiasts recommended starting in neutral which would allow fluid to fill up pump area quicker. Been doing that but still is a bit hard shift. I'm hearing it's a converter problem? Duster has stock converter. Appreciate any input/suggestions....
     
  2. CudaFactHackJob

    CudaFactHackJob Well-Known Member

    Messages:
    1,839
    Likes Received:
    682
    Joined:
    Mar 17, 2016
    Location:
    Hemet, Ca.
    Local Time:
    5:00 PM
    Sometimes builders replace the waved retainer ring in the front drum with a flat one to increase 2-3 shift firmness, but it creates a hard reverse engagement. Of course, if the direct clutch has any wear, it will engage hard, plus you'll lose third gear when it warms up on a hot day; but in that case, reverse would also be delayed. Not a converter problem.
     
  3. Zak

    Zak Well-Known Member

    Messages:
    57
    Likes Received:
    2
    Joined:
    Jun 3, 2010
    Location:
    Valdosta, Georgia
    Local Time:
    6:00 PM
    Thanks bud
     
  4. oldkimmer

    oldkimmer FABO Gold Member FABO Gold Member

    Messages:
    20,817
    Likes Received:
    7741
    Joined:
    Nov 11, 2006
    Location:
    Kindersley, Saskatchewan,
    Local Time:
    5:00 PM
    The rear band probably needs adjusted. Kim
     
    • Like Like x 1
    • Agree Agree x 1
    • Bewy

      Bewy Well-Known Member

      Messages:
      1,505
      Likes Received:
      962
      Joined:
      Jan 1, 2021
      Location:
      Australia
      Local Time:
      10:00 AM
      Yeah, rear band first. That is why it is called the low/reverse band.
       
    • monc440

      monc440 Member

      Messages:
      10
      Likes Received:
      6
      Joined:
      Nov 9, 2012
      Location:
      Motor City
      Local Time:
      6:00 PM
      Yes check your low reverse band adjustment first. How many miles on the trans? Did this just start or something new? More information will be helpful.
       
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s FABO Gold Member

      Messages:
      22,058
      Likes Received:
      9226
      Joined:
      Jan 19, 2014
      Location:
      South-Central Manitoba,Canada, 900ftelevation
      Local Time:
      5:00 PM
      In reverse, the front pump output is not regulated besides the hi-pressure relief valve.
      To make reverse, the trans uses the Hi-drum and the L/R band.
      As mentioned, the Hi-drum uses a wavy spring to cushion engagement.
      The L/R servo uses a spring to slow it down.
      Now it just so happens that the Accumulator spring is about the same size and fits in there very nicely......... but it is a far stiffer spring. If those two are swapped , Bam! as soon as the L/R servo sees pressure it instantly slams the band.

      To make First gear, the trans uses two methods;
      If you put it into Drive, the trans will engage the Forward clutch and use the rear Sprag to make sure the output shaft turns in the correct direction. The L/R band is not used.
      In Manual Low. the L/R band is used again to anchor the business.
      You can use this oddity to help diagnose the servo-spring.
      If it shifts softly into Drive, then all is well. But
      if it bangs into BOTH manual Low and Reverse, I would suspect the servo spring. Especially if grabbing Second is a lil mushy
       
      Last edited: Jan 14, 2022 at 12:25 PM
    • monc440

      monc440 Member

      Messages:
      10
      Likes Received:
      6
      Joined:
      Nov 9, 2012
      Location:
      Motor City
      Local Time:
      6:00 PM
    • Zak

      Zak Well-Known Member

      Messages:
      57
      Likes Received:
      2
      Joined:
      Jun 3, 2010
      Location:
      Valdosta, Georgia
      Local Time:
      6:00 PM
      Thank you all for enlightening me on the internal operation. I appreciate it fellas...
       
      • Like Like x 1
      • 66 Valiant wagon

        66 Valiant wagon Well-Known Member

        Messages:
        228
        Likes Received:
        175
        Joined:
        Jun 16, 2019
        Location:
        Minneapolis, MN
        Local Time:
        5:00 PM
        If your idle is really high it'll bang into reverse also.
        Just an extra $0.02
        Good luck
         
      • CudaFactHackJob

        CudaFactHackJob Well-Known Member

        Messages:
        1,839
        Likes Received:
        682
        Joined:
        Mar 17, 2016
        Location:
        Hemet, Ca.
        Local Time:
        5:00 PM
        I've seen cars with a lot of ring and pinion clearance slam in reverse but not drive.
         
        • Agree Agree x 1
        1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
          By continuing to use this site, you are consenting to our use of cookies.