Speedometer or cable problems?

Mopar Interiors

  1. dostroupe

    dostroupe Well-Known Member

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    The speedometer in my '70 Duster worked just fine, no jumping and accurate. I had to pull the cluster to install a new dash pad. When I drove it after putting everything back together the speedometer was fine. After a few miles it started jumping all over the place and making a noise like hitting a little bell. So, I slowed down and headed back home not wanting to break the speedometer. It still bounced from below zero to more than max. It finally went to below zero and just started quivering. The strange thing is the odometer is still working fairly accurately. Speedometer or cable?
     
  2. RedFish

    RedFish Well-Known Member

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    Sorry to say it sounds as if the cable applied too much force on a already worn instrument. There aren't any snap rings, bearings or much of anything really. A steel shaft is held in place in the aluminum bore with only a brass collar. There is a steel thrust washer between brass collar and aluminum bore but you can bet there is wear / more movement there. The square drive port gets a good load of contaminated grease packed into it too. Pull the cable out and shove it back in again without cleaning either cable end or port might have been fine for the service tech when all this was 5 even 10 years old. 30 + years old is different.
    In the end its kind of like old plumbing, we'll never know how much longer it might have worked had it not been disturbed. Consider that you also disturbed the left/right/up/down directional force applied by that cable attach also. How straight the cable is routed to the back of this instrument directly effects how long it lives. Like I said, It wasn't built like a machine.
    And the odometer is direct gear driven. The speedometer is not. This is 2 instruments in one housing sharing only the cable that drives them.
     
  3. dostroupe

    dostroupe Well-Known Member

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    That's about what I was thinking, broken speedo. Dang, I was so proud it was still working. Get out the wallet I guess!!! Thanks Redfish.
     
  4. RedFish

    RedFish Well-Known Member

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    So what to look for in a used speedometer.... In most cases, The seller will photograph the instrument while it rests on its input. If that light bias force is lifting the needle at all, that is showing the wear there. And some wear is expected. I might buy and install one with 5mph lift if the price was right but any more than 7 mph, keep on shopping. In any case you'll need to clean the input and route that cable in as neutral as possible. Good luck
     
  5. 1969383S

    1969383S FABO Gold Member FABO Gold Member

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    Don't give up on it yet. Check your cable to speedo again and make sure it snapped in correctly. Mine did the same after resto and after pulling the cluster for new gauges I cleaned and lightly lubed after complete disassembly. Made sure it snapped on, but not putting pressure forward and it is working nice and smooth now.
     
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    • RedFish

      RedFish Well-Known Member

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      I clicked agree on the above. I hadn't considered that one might go back in and find a sweet spot where the speedo parts don't collide. Good luck with it.
       
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      • dostroupe

        dostroupe Well-Known Member

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        Thanks guys, I think I'm going to order a new cable anyway. I didn't like the way the plastic connector looked. Then see if I can clean up and lube the speedo.
         
      • 1969383S

        1969383S FABO Gold Member FABO Gold Member

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        Yes good idea.

        Mine was a brand new Mopar cable out of the package and was just not ready to give in. My odometer was working away just fine but the needle was wildly swinging. That thing is like magnetic and the odometer geared. The odometer will turn it has no choice or bind to failure. A good cleaning and assurance the cable stop was not pushing on the head made all the difference. Good luck!
         
      • 1969383S

        1969383S FABO Gold Member FABO Gold Member

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        You are darn right about the cigarette smoke and years of contaminates. That crap gets everywhere! Careful cleaning and re-lube can do wonders!
         
      • famous bob

        famous bob mopar misfit

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        I pulled the entire mess apart and re zeroed the odometer, cleaned everything and lubed the cable w/ weed eater cable lube. It works, but bounces about 5 m.p.h. , but seems to read fairly correct. Well it did before I put 29.5 inch tall tires on it. The speedo gear in the trans. is for a 28" tall tire.
         
      • 1969383S

        1969383S FABO Gold Member FABO Gold Member

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        Was running 4.56 with 42 tooth gear and 28" tire. Downsized to 3.55 with the appropriate gear. Mine is happy now. Did the same thing but did not zero it. Put it back where it was at 28,365. The shaft for the odometer was very dirty and crusty.
         
      • dostroupe

        dostroupe Well-Known Member

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        Well, crap, I installed the new cable, no luck. So I pulled the speedometer to inspect/clean. I cut the old cable off to use in a drill to bench test. What I found was, the little spring that under the needle is not stationary and the (rotor?) is not turning like it should. So, rather than totally messing it up, is there anyone here that can repair it, I would like for it to work properly. Or at least recommend a company for repair. thanks
         
      • RedFish

        RedFish Well-Known Member

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        Speedometer repair aint cheap no matter which shop you send it to. You could try to find a good used one but that's a gamble today. Good luck
         
      • Alaskan_TA

        Alaskan_TA Well-Known Member

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        One more thing to try......

        Disconnect it at the transmission & push the inner part up inside the sleeve.

        Sometimes they get pushed down when hooking to the cluster.
         
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