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th400 transmission shifts to fast.

Discussion in 'Chevy Trucks' started by plummermark2002, Mar 23, 2004.

  1. plummermark2002

    plummermark2002 Member
    Messages: 30

    Thanks much for the info on my th400 tranny, i got it in and it works great, except for it goes through the gears so fast that it's in third gear by the time it's going thirty five or so miles per hour, so it tends to make my old faithful 350 lug abit until its upto speed, in the reply i recieved previous to this you mentioned that the valve body is calibrated different on a tranny powered by a deisel engine, is there much to recalibrating this, or is this something that requires a professional? any help on this would be greatly appreciated. plummermark 2002!
  2. Bucksnort

    Bucksnort Junior Member
    Messages: 28

    I ain't an expert but shifts are controlled by vacuum modulator on Th400.I found that out on my 70 Chevelle SS.My tranny was shifting too quick for my liking and I put an adjustable modulator on the tranny.Very easy to do.Get one at your speed shop or Jegs,Summit.
  3. 86burban

    86burban Senior Member
    from chicago
    Messages: 130

    I thought you adjusted the kickdown cable on the carb?

  4. ratplow408

    ratplow408 Member
    from PA
    Messages: 33

    No cable on 400.