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Quick GM vaccuum modulator question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by newyorkin, Nov 22, 2001.

  1. newyorkin

    newyorkin 1 ton status

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    My wife's '89 Grand Prix has a TH440 with a vaccuum modulator. Which direction should I turn the screw to smooth out the shifts? Right now they're very hard and late... Clockwise or counter clockwise to smooth it out and make the shift a little earlier?

    Thanks y'all!

    Ratch
    <a target="_blank" href=http://k5.8m.com>k5.8m.com</a>
    Welcome to America.
     
  2. chevyfumes

    chevyfumes Court jester

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    Watch for the muzzleflash!
    I think counter but I'm not sure.but atleast you've got a 50 50 chance...

    <font color=blue> I'd rather have a bottle in front of me, than a frontal lobotomy!
     
  3. HarryH3

    HarryH3 1 ton status Author

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    You usually can't make a very big change in the shift times with the modulator. You might have to change the weights and springs on the governor if it's shifting really late. Not a terribly hard job, but certainly not as easy as turning a single screw. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
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  4. newyorkin

    newyorkin 1 ton status

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    I re-evaluated it, and I actually shouldn't say it was shifting late, just shifting wierd and rough. This particular tranny shifted perfect and was pretty low mileage in it's donor wreck. The shifting changed when the guy that did the swap for me used the brand spankin new modulator from the toasted tranny, but never adjusted it (that was 1 1/2 years ago and she's just dealt with it). Before we went to the in-laws today, I turned it a hair clockwise and noticed a big improvement so far... That was why I asked real quick on here, I wanted to adjust it before the trip and not have to pull over and re-adjust it. Then I went and stripped out the screw cause of the rotten angle, so it looks like tomorrow the car gets another new modulator...

    Anyway, thanks Harry, if I can't straighten this out via modulator adjustments, I will start playing with the governor... I never futzed with too much on a transaxle, though.... Thanks for the response!

    Ratch
    <a target="_blank" href=http://k5.8m.com>k5.8m.com</a>
    Welcome to America.
     

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