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Speedometer Gear Question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 78Blazer, Mar 21, 2001.

  1. 78Blazer

    78Blazer 1/2 ton status

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    My speedometer does not work and I have come to the conclusion that it is becuase of the transfercase gear. How and what has to be done to change this gear? It is on a 203 case from a 78 blazer.

    Scott
    78blazer
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    If its anything like in the transmission, and I'm pretty sure it is, you just crawl under the truck, find where the speedo cable goes into the t-case, disconnect the cable, unbolt and remove the gear retainer, and there you go. You may have an adapter on the speedo gear output which could have failed as well...if you DO have an adapter, you can remove it and screw the cable directly to the t-case, and see if that fixes it.

    You can also disconnect the gauges, pull them, and test drive and watch the speedo cable to see if it turns. If its turning, its in the instrument cluster....

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  3. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Did you check your cable? If it isnt moving at all chances are its broke. If the speedo flutters then its probably the speedo gears.

    [​IMG]
     
  4. 78Blazer

    78Blazer 1/2 ton status

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    I checked the cable its good. It quit when it was in my 78 and after I tore it all apart I checked the cable there and the cable was good. I know the guages are good so that leaves the transfercase.



    Scott
    78blazer
     
  5. Wheels

    Wheels 1/2 ton status

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    If your transfer case still has the adaptor on it, there is a pin that goes from the adaptor to the drive gear (square at one end and has a small key at the other about an inch and a half long). See if it is sheared or if the squared shank (part the fits the drive gear in x-fer case) is rounded. If it's rounded, more than likely the drive part in the case is rounded also. The pin is about $7 and the shaft is $13 at Chevy. Also, the adaptor has gears in it that can jam up every now and then that will shear this pin. My .05.
     
  6. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Yeah, what he said, lol. You can change your drive gear by taking your tailshaft off and just pulling it off the shaft. Pretty simple, the driven gear is even simpler

    [​IMG]
     

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