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speedometer cable to coupling to L coupling to T-Case?( !! UPDATED !! )

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BorregoK5, Jan 22, 2002.

  1. BorregoK5

    BorregoK5 1/2 ton status

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    My speedometer stopped working recently. I finally got around to checking the cable from the transfer case and it is fine. Now I remember finding a small package of black speedometer gears in the truck when I bought it and the speed-o always read faster (not slower) than I was actually going with my 33's. Either the original owner had much larger tires or swapped in a bad gear. My speed-o cable twists on to what looks like an under or overdrive coupling, then to an L coupling which finally mounts to the np203 t-case. I can't find this first under/over drive coupling in any chevy books so I'm assuming that it is an aftermarket add on for speed-o corrections. I bypassed this coupling and screwed the speed-o directly into the L coupling but it still doesn't work. Before I yank this L coupling, can anyone identify which of these is supposed to be there and what I might find under the L coupling (hopefully a stripped gear)?

    ( !! UPDATE !! )

    I removed the speed-o "L" coupler from the T-Case and spun the male end... the female end spun accordingly. Since I had already checked the cable as described in a reply below then my problem had to exist in the T-Case. The male end of the "L" bracket is removeable so I pulled it out and placed the proper end up in the T-Case to see if it would spin freely but it did not... untill I seated it all the way in. I pulled it back out and looked carefully at the 1inch cable and noticed that the edges were slighly smooth around one spot but still held a good square shape. I threw a rubber gasket inside and in between t-Case and the L coupler to place the smoothed edge of the cable in a different location and low and behold the speed-o works. I'm a little concerned that an area of the cable which is still more square than round and hardly distinguishable from an area of the cable whcih works makes a difference. This leads me to believe that the T-Case side has begun to round where the cable slips in from the L-Coupler rather than the L- Coupler itself. It looks to be removeable with a large nut on the T-Case but my Manual doesnt cover this area. Has anyone pulled this from the T-Case before.. Mine doesn't seam to want to come loose (tight nut?)


    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a><P ID="edit"><FONT class="small">Edited by BorregoK5 on 01/22/02 08:04 PM.</FONT></P>
     
  2. 78Blazer

    78Blazer 1/2 ton status

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    Re: speedometer cable to coupling to L coupling to T-Case?

    Hey I am having the same problem with mine right now. The little L looking thing is a transducer and is not aftermarket. It allows them to use different gears and the speedo still reads the same becuase of the transducer (something like that)anywasy when you pull the transducer off there should be a straight pin that sticks out of it and into the transfercase chances are that it is broke. I think it is about 15.00 from the dealership . Dealer Item only.

    Scott
    78blazer
     
  3. BorregoK5

    BorregoK5 1/2 ton status

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    Re: speedometer cable to coupling to L coupling to T-Case?

    Thank you, I'll pull it off today and check!

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a>
     
  4. Innerpiece

    Innerpiece 1/2 ton status

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    Re: speedometer cable to coupling to L coupling to T-Case?

    it wasn't exactly clear in your post -- but if you have a mechanical speedo -- pull the cable off at the closest junction to the speedo and twist it by hand -- both directions -- when you spin it the correct way it should jump 10-15 MPH ... then you know that the speedo works and you can start working down the line ... it might work with an electronic speedo but I have no experience with those ...
     
  5. BorregoK5

    BorregoK5 1/2 ton status

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    Re: speedometer cable to coupling to L coupling to T-Case?

    TTT

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://24.55.50.76:81/k5/> Pictures</a>
     
  6. BigBadCad

    BigBadCad 1/2 ton status

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    I don’t know if this is relevant information or not, but when my reduction gear (speed-o "L" coupler) went bad, I pulled it off my NP205 and ran the cable directly in the transfer case without the reduction gear. I did this right after I purchased the truck and jumped from stock size tires to 33’s. I was lucky because the speedometer ended up dead on without the reduction gear (verified by GPS). This might work for you also…I always like to try the cheap fix first.

    1980 chevy 4x4 1-ton crewcab, 500 caddy, York OBA...work in progress.
     
  7. BorregoK5

    BorregoK5 1/2 ton status

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    Actually , this is really relevent.. but my cable is about 1/2 inch to short... I tried! It seams to be working fine now with the spacer.. but how long will that last!!! Anyone have an np203 teardown scanned in which shows the speed-o section?

    I started with nothing and I still have most of that left! - <a target="_blank" href=http://www.echobit.com:81/k5/> Pictures</a>
     

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