muncie pops out of gear

Discussion in 'Transmission & Driveline Topics' started by cody, Jul 14, 2004.

  1. cody

    cody Veteran Member

    recently rebuilt muncie never popped out of reverse before now reverse pops out every few seconds and 4th pops out when i let off the this just a linkage adjustment or something internal..thanks
  2. 70modelz28

    70modelz28 Veteran Member

    Jan 14, 2004
    Hughes Springs, Tx
    mine did the same thing out of like 2nd. the linkage was loose
  3. COPO

    COPO Veteran Member Lifetime Gold Member

    Sep 15, 1999
    Or syncros are gone or the 3-4 hub assem is worn where the synco locks in. Reverse does not have a syncro.

    1970 Z28
    Home Page on 1970 Z28

    [This message has been edited by COPO (edited July 15, 2004).]

    [This message has been edited by COPO (edited July 16, 2004).]
  4. cody

    cody Veteran Member

    if the 3-4 hub assem. is worn would it cause me to have probs with 3rd gear popping out too?B/C it stays in no matter what,just have probs with reverse when backing up if i dont hold the shifter and 4th when i let off gas.thanks in advance
  5. 75 400 4 Speed

    75 400 4 Speed Veteran Member

    Feb 8, 2002
    Jefferson City, MO
    First step is to get under the car, remove the linkages from the trans. Put an alignment pin in the shifter. Now, place all three shift levers in neutral. Put the linkage up to the hole and turn the joint in or out until it slides in with almost no resistance. Now the nuetral bias of the shifter and the tranny should be aligned.

    If you have a Hurst shifter with adjustable shift stops, they could be in too far. With the car off, put the shifter in Reverse, First and Third while watching the shifter plate. If it hits the rear shift stop, you need to back it out until you have about .040 inch clearance give or take a little when you are just eyeballing it. Then shift into Second and Fourth and check the front stop. Adjust accordingly.

    If these adjustments don't correc the problem, it is internal.

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    69 SS 350 4 Speed
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    [This message has been edited by 75 400 4 Speed (edited July 15, 2004).]
  6. tom3

    tom3 Veteran Member

    Aug 1, 1999
    The reverse deal could be the linkage, reverse arm is easy to get in a bind. The fourth gear can be too much clearance between the input and tail shafts, too thick a gasket at rear of gearbox, or a worn syncro sliding sleeve, or the small teeth on the input shaft. If the tranny was indeed rebuilt all this should be in good shape so hopefully it is the linkage, but not optimistic.
  7. XK1

    XK1 Veteran Member

    Jul 8, 2001
    St. Johnsbury, VT
    My first M21 popped out of 4th whenever I let off, then all the time. I ended up replacing the input shaft (4th gear), and the hub assy.

    76 Camaro, Blue/Black, .030 350, M21, Z28 body parts.
    90 4WD S-10 rustbucket snowbank reducer

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