Shifting from 2 to 3

Discussion in 'Transmissions' started by Warp9, Aug 10, 2019.

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  1. Warp9

    Warp9 Member

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    72 grabber, c4 no issues until lately it shifts late into 3rd when cold. After it warms up it shifts great. Fluid is clean and smells fine. Any ideas, I'm at loss.....
     
  2. Krazy Comet

    Krazy Comet Tom

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    Check your vacuum line, especially at the modulator end. Loose fitting hose can give weird symptoms.
     
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  3. Warp9

    Warp9 Member

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    Thanks krazy, I check all the hose ends and put clamps on them. Hoses look fine. Same problem, won't shift into 3rd before 50 mph. After its warmed up it shifts at 30...... I did notice my back up lights aren't coming on, could be the neutral safety switch. Would this be connected?
     
  4. Krazy Comet

    Krazy Comet Tom

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    The neutral safety switch has no effect on shifts.

    The single line modulators that have vac connection out top are usually adjustable, require a small flat blade screwdriver. I'd back off on adj(CCW) approx one turn.
     
  5. Warp9

    Warp9 Member

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    I don't think I will monkey with the modulator, it shifts fine after it gets warmed up and I don't want to change that. Got me wondering, if it had the wrong fluid (dextron) in it, would that cause the issue I'm having. I haven't serviced the trany since I got it and don't know what was put in it. I just assumed that it was type F.
     

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