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What is a common cause of Speedo failure?...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 77K5Blazer, Jun 14, 2002.

  1. 77K5Blazer

    77K5Blazer 1/2 ton status

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    My speedometer/odometer is not in operational order. I know for a fact that the speedo cable is good, I already checked that. My next guess would be the gear inside the Tranny that transmits motion to the cable itself. Anybody know the common things to go out? BTW, it's a 77 w/ 4 speed and 205 case if that helps anything. Thanks in advance...
    Later, Allan /forums/images/icons/confused.gif
     
  2. FL84K5

    FL84K5 1/2 ton status

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    too much junk food? oh speedometer, sorry
     
  3. kennyw

    kennyw N9PHW Premium Member

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    I have found most of my problems with the speedo cable when it stops suddenly. Broken cables mostly.

    Worn out plastic gears will cause bouncing speedos sometimes.

    And once I had a speedo itself that was just no longer magnatized properly.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, you can pull the cluster, and I guess either drive it and watch the cable end to make sure its turning, or simply try twisting the cable by hand. Sitting, you shouldn't be able to turn the cable since the speedo gears in the transfer case aren't moving.

    The "head" (bolted to the back of the guage) can also wear out, just some gears, springs, magnets, what have you, and they just fail. Does the odometer work? Theoretically, I guess the odometer could work, but not the needle, which would indicate the head assembly obviously.
     
  5. 77K5Blazer

    77K5Blazer 1/2 ton status

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    The Odometer also does not work. I disconnected the cable at each end, and could turn one end while a buddy watched the other end spin. I pulled the cluster, and everything appears to be in order, however I didn't drive it and see if the cable moved. I should be installing a stereo this weekend, so I'll pull the cluster again and see what happens! Thanks for the help!
    Later, Allan
     
  6. chevyfumes

    chevyfumes Court jester

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    Watch for the muzzleflash!
    mine is really wierd I had to cut about 1/2" off of the 203 side to make it work Don't ask me, the only thing I could figure is that someone installed the wrong housing where it goes into the 203, anyone have pics of the housing....
     
  7. Jed

    Jed Registered Member

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    I pulled the cable out of the xfer case and had someone tell me whether the speedo needle moved when I turned it with my fingers. It did so then I took off the ratio adapter off (between the cable and the xfer case) and found that the square drive pin was twisted and sheared off (removed the broken bit from the xfer with a magnet). My guess is that the cable got caught on something while wheeling, bound and broke the drive pin. These adapter dealiers are about 100 Canuck bucks tho /forums/images/icons/frown.gif. I just put the cable directly into the xfer and hope my mental arithmetic will handle the 1.2 ratio for now (the ratio was stamped on the adapter case).
     
  8. muddin4fun

    muddin4fun 3/4 ton status

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    you should make sure the cable is pushed all the way into the speedo. Every now and then, mine falls back a little.
     

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