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  •  » 66 C4 shifting issues

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    7/19/2013 8:58 PM  #1

    zakdaddy99
    FYI Addict

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    From: Olathe, KS
    Registered: 4/01/2013
    Posts: 150

    66 C4 shifting issues

    I drove my Mustang today and noticed that it was shifting later and harder than it has been. It is a 66 302 with a C4.I drove it Monday and all was fine. Today it is shifting into 2nd between 25-30 mph and into 3rd at over 40. It was shifting almost immediately into 2nd and into 3rd at about 25. No changes have been made. The shifts are very firm also. Could the modulator be bad? I replaced it about 6 years ago. 

    I'm going to check for vacuum leaks and try to adjust it tomorrow. 

    Thanks in advance for your input.

    Good, fast or cheap. Pick any two...
     

    7/20/2013 7:11 AM  #2

    BobC
    I FYI 24-7

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    From: Clinton, MI
    Registered: 4/01/2013
    Posts: 447

    Re: 66 C4 shifting issues

    Check for vacuum leaks in the tubing that runs from the manifold to the modulator. It us usually a rubber tubing at the top and bottom with a steel line between. Then you can check the modulator by removing the rubber vacuum line  at the modulator and see if transmission fluid comes out.  If you get fluid, the modulator is bad.  I'm sure someone else will chime in with some more ideas.
    Best of luck

    Bash Host MSBB XVI.       BobC    1966 Mustang Coupe
     

    7/20/2013 7:43 AM  #3

    Derek
    I FYI 24-7

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    From: Eatonton GA
    Registered: 4/01/2013
    Posts: 549

    Re: 66 C4 shifting issues

    I know this may sound stupid but, Check the fluid level. Also kinked or leaking cooler lines can also do that. Somtimes leaks can be sneeky. Only leaking under pressure while your driving and not when the cars just sitting idiling.

    It's hard to type "funny"
     

    7/20/2013 9:16 AM  #4

    zakdaddy99
    FYI Addict

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    From: Olathe, KS
    Registered: 4/01/2013
    Posts: 150

    Re: 66 C4 shifting issues

    I think I found the problem. Vac hose from carb to steel line was cracked. No vac to modulator. It's been raining here so no test drive yet but I'm sure that will fix it. 

    Thanks for your input.

    Dan

    Good, fast or cheap. Pick any two...
       •Thread Starter
     

    7/21/2013 8:24 AM  #5

    zakdaddy99
    FYI Addict

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    From: Olathe, KS
    Registered: 4/01/2013
    Posts: 150

    Re: 66 C4 shifting issues

    Drove it to the donut shop this am and all is well.

    Good, fast or cheap. Pick any two...
       •Thread Starter
     

     

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