Loss of Reverse

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    Author Topic: Loss of Reverse  (Read 1508 times)

    Offline cv70chall

    • Jr. Member
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    • Posts: 301
    • 1970 Challenger
    Loss of Reverse
    « on: January 20, 2019 - 11:14:33 AM »
    Hi Everyone,

    Just replaced my torque converter with a higher stall(2K) and I have three questions.

    1. Car shifts out of first almost immediately- roughly after about 2 seconds. Is this a band adjustment which would be external or something else? I know changing from a stock converter to a higher stall must alter the shifting sequence, right?

    2. Car still "clunks" when placed into reverse. Is this a servo adjustment within the pan that can be done to calm it down?

    3. After driving the car for about a week, I was backing it into the garage and heard a metal "click" and then...wholla...I lost Reverse.
    Is this something relatively simple, such as a bracket or linkage that could have fallen off/ become disconnected or a failure of the reverse band itself?

    Thanks
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    Offline 73440

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    • Posts: 1826
    Re: Loss of Reverse
    « Reply #1 on: January 20, 2019 - 07:37:32 PM »
    For #2 , what is the idle speed , is it high ? Are the motor and transmission mounts in good shape ?
    For #3 , is it only reverse you don't have ?

    This is a good book on the 727 : https://www.penguinrandomhouse.com/books/288597/torqueflite-a-727-transmission-handbook-hp1399-by-carl-munroe/9781557883995

    Will add some photos of troubleshooting items shortly.
    « Last Edit: January 20, 2019 - 07:46:13 PM by 73440 »
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    Offline cv70chall

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    • Posts: 301
    • 1970 Challenger
    Re: Loss of Reverse
    « Reply #2 on: January 21, 2019 - 08:32:25 AM »
    Morning,

    Idle speed is sitting at around 850-900rpm.
    Yes, all the other gears work fine. I was backing into the garage and applied some gas to get over the little hump at the garage and thhat's when I heard the metal "click" and then no reverse.
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    Offline jhaag

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    • Posts: 616
    Re: Loss of Reverse
    « Reply #3 on: January 21, 2019 - 10:22:03 PM »
    A quick 1, 2 shift is most likely the adjustment of the line pressure linkage from your crab. If you do not fix that it will quickly burn up your trans. As for the reverse problem I can offer no suggestions other than check all the linkage.
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    love 70 Challengers

    Offline 6packCuda

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    • Posts: 1932
    • Eagle, NE... Member since 11/17/06
    Re: Loss of Reverse
    « Reply #4 on: January 26, 2019 - 10:53:22 PM »
    #1...Sounds like kickdown adjustment issue. Try adjusting it so that it pushes the lever on the trans further back.

    #2...Check for excessive slack or movement in your u-joints.

    #3...Sounds like you’ve lost rear band apply. Probably cracked or wedged rear servo piston. You’ll have to drop the pan to see.
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    Dave

    Offline cv70chall

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    • Posts: 301
    • 1970 Challenger
    Re: Loss of Reverse
    « Reply #5 on: February 20, 2019 - 04:54:39 PM »
    Discovered it was a broken band. Replaced and we're back in business, however, I still have the CLUNK when I go into reverse.
    Is this an adjustment? Could the spring be out of adjustment at the servo? U-joints are new and tight/ no play. Kickdown and band adjustments are set properly.
    I don't want this to be the reason the band broke.


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    Offline 70chall440

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    Re: Loss of Reverse
    « Reply #6 on: February 20, 2019 - 09:48:12 PM »
    Did you check your U joints when you were working on the trans? In my experience, most of the time you get the rear "clunk" its either U joint related or differential (rear end) connected.
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    Offline cv70chall

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    • Posts: 301
    • 1970 Challenger
    Re: Loss of Reverse
    « Reply #7 on: February 21, 2019 - 10:51:45 AM »
    Yes, the U-joints are good and tight (new) and the diff is also good and tight.
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