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T-400 transmission wont engage in drive

Discussion in 'The Hokey Ass Message Board' started by Louie T, Apr 14, 2011.

  1. Louie T
    Joined:
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    California

    Louie T Member

    Ok...so I need some help, and don't know where to start. I have a T-400 transmission. Well yesterday it decided that it wasn't going to shift into drive. I could rev it a little and it would jerk into gear and it worked perfectly, shifted smoothe, no problems.....well today i tried to go somewhere and the trans decided it wasn't going to go into drive no matter what I did....it goes into reverse just fine.....but refuses to go into drive...I also tried to drop it into 2nd, with no luck....thank you
    Last edited: Apr 14, 2011
  2. Torana68
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    Torana68 Member

    sounds like pan off and service/look and adjust bands to me, might fix it, whats the oil smell like?
  3. Louie T
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    Louie T Member

    it smells like normal ATF...doesnt smell burnt.
  4. 57ford/60thunderbird
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    hamilton ohio

    57ford/60thunderbird Member

    try replacing the vacuum modulator
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  5. Louie T
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    Louie T Member

    what does the vacuum modulator do? i was reading that it could possibly be the drive clutch but like i said, it ran perfect when it eventually engaged in drive....now it wont engage at all...if the vacuum modulator was bad would that effect reverse too? it seems weird that the tranny would just blow without warning...it ran perfectly when it eventually engaged in drive...thank you for the replies.
  6. Torana68
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    Torana68 Member

    if it smells ok thats a good start, when was it adjusted last? does it drive in 2nd?
  7. Torana68
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    Torana68 Member

    good idea that , have a look and see if its full of oil
  8. Louie T
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    Louie T Member

    i just bought the car, i dont know when it was adjusted...it wont go into any forward gear, it moves forward slowly at higher rpms, i dont want it to "jerk" into gear while its at a high rpm..it goes into reverse no prob...when this problem started it hesitated before it went into drive and then worked perfectly...it seems like something isnt allowing the tranny to fully engage in drive....could this be the vacuum modulator? and what if its full of oil? what does that mean?
  9. Torana68
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    Torana68 Member

    if its full of oil the diaphram has a hole and its stuffed...
    pinched from somewhere or other:

    The Turbo 400 has a modulator on the passenger's side of the transmission pointing towards the passenger's door. Pull the rubber line off the modulator and see if transmission fluid comes out of the line. If fluid comes out, the modulator is no good
  10. Louie T
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    Louie T Member

    ok...would a bad modulator cause the problem that im having?
  11. Torana68
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    Torana68 Member

    wont help .... maybe is all I can say
  12. Louie T
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    Louie T Member

    ok..ill replace it tomorrow...maybe its time for the t700R
  13. Torana68
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    Australia

    Torana68 Member

    check it first, you might be lucky and all it needs is a service

    edit : maybe the T400 has no band adjustment? hopefully someone who knows these will chip in soon :)
    Last edited: Apr 14, 2011
  14. Igosplut
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    Cape Cod MA

    Igosplut Member

    No. A bad modulator will keep it from shifting into HIGHER gears... Not from engaging 1st. One thing I can think of off the top of my head is:

    Somethings failed in the valve body. Reverse and first are the same band so to speak...So if you have reverse, you should have first gear (meaning the 1st/reverse hub hasn't failed). Shifting is all in the valve body for the most part. I've seen 400s with really bad shifting/non upshifting be fixed by a change in valve body's. To have forward gears one day, and then have them gone the next (especially you saying that you had to rev it up and it engaged) sounds to me like hydraulic failure in the valve body..
  15. wheel28
    Joined:
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    Land of Pears, Tx

    wheel28 Member

    Sounds like the forward clutches are bad or the forward clutch piston seal is gone.
    Wheel


    [​IMG]
  16. Louie T
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    Louie T Member

    do i ned to pull out the tranny to fix this or can this be repaired inside the car?
  17. bigdav160
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    Klein, Texas

    bigdav160 Member

    I disagree with the above statement.

    Will it go in manual 1? If it does, then it means the low roller clutch is going out.

    If there is no difference then the forward clutch needs work.
  18. Louie T
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    Louie T Member

    reverse is the only gear i have...no forward gears whatsoever...the strange thing is that this problem started by it hesitataing before it went into drive....once there it worked perfectly...now it wont engage in any forward gear...hmmmm....maybe its 700R time

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