shifting problem on 87 ZX auto trans

  • jerryparks
    jerryparks
    Senior Member
    • 242

    shifting problem on 87 ZX auto trans

    I want to cut back the shifting speed on my 87ZX. It shifts into 3rd at about 38 miles per hour and around town; this is too high as the motor speed is to high. Where is the control mechanism to reduce this to around 25MPH?
  • jerryparks
    jerryparks
    Senior Member
    • 242

    #2
    Sure could use a knowledgeable reply on this issue !!
  • FrozenZ
    FrozenZ
    Senior Member
    • 584

    #3
    Jerry - short answer, there isn't anything you can adjust to do this. There's no control mechanism. The "digital control device" is *just* for the mechanical lockup. 38mph is at the top end of the shift range but is still about where it should be. RPM should be in the 1900-2K range at that speed when it shifts. If it's way higher than that you may need a new vacuum modulator.

    If for some reason you really, really want this to happen a performance transmission shop could do it but it'll cost $$$. Pretty much the only thing you can do on your own is to try dropping your idle a little if you have it set really, really high (like, you're idling in D at 1200) for some reason. That MIGHT help a bit. New vacuum modulator isn't really expensive or really complicated to install, but it's not going to take your 2-3 shift down to 25mph.

    The question is why you'd want to - 3rd at 25mph under any load at all is going to be really hard on the tranny, it's going to be lugging really badly. This isn't a modern 6-speed, you only have the three non-highway gears.