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Old 04-04-2021, 11:50 PM   #1
cj847
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Speedometer "repair"

After lubing my speedometer cable 3 times and still having noise, I decided that my issue my be in the actual speedometer itself. So, I took it apart. Now that I am done, I see why the noise is generally the cable, there is almost nothing to go wrong inside the speedometer head. I can't say that I know what I am doing here. I just couldn't find any posts with this info when I searched.

I took the speedometer out of the cluster, then removed the needle.

Next I removed the instrument face.

Then removed the odometer.

Then I was to the actual speedometer head

I opened it up and the cup was empty and clean. The shaft and needle are attached to this cup. Note: there is a delicate hairspring that returns the needle to zero, that I did not disturb.

Inside this cup was a magnet that turns to move the needle. The cup basically "floats" above this magnet that is turned by the speedometer cable.

I reassembled the head and put 2-3 drops of 3 in 1 oil in it (although it appears it is not supposed to be lubed based on how clean it was on disassembly). I put the oil in the holes in picture 2 below (ie I could have done it without disassembling the head itself)

After about 30 miles of test driving, my speedometer is quiet. I am not sure if I fixed it, or if I accidentally got the speedo cable in a position that made it happy or what. I do NOT recommend doing this until you are literally about to order a new speedometer.
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Old 04-05-2021, 11:57 AM   #2
pjmoreland
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Re: Speedometer "repair"

Nicely done. That was a good idea not to mess with that spring. The fixed end of the spring can be adjusted, if need be, where it attaches to the speedometer body. It would need to be wound up the correct number of turns though to start with. Seems like that would be a nightmare to figure out without a speedometer calibration machine. I adjusted mine a small amount a few months ago because it was off by 4mph at all speeds.
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Old 06-15-2021, 11:18 AM   #3
cj847
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Re: Speedometer "repair"

SOLUTION!

After months of trying to get my speedometer to quit making noise, I think I have found the solution. In my case the speedometer would start screeching after a few miles of driving. I had already bought a new speedometer cable and re-lubed it. So, I thought, when things get hot they expand. Maybe my speedometer cable is a little long compared to the sheath around it.

I disconnected my speedo cable from both ends and clipped about 1/4" off of each end. I have driven several hundred miles noise free. Apparently, the cable was too long so when it heated up it pushed the magnet inside the speedo into the case. Anyway, a possible solution for those who have a problem.
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Old 06-16-2021, 09:20 PM   #4
70STOVEBOLT
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Re: Speedometer "repair"

My speedo used to be about 3-5 mph off so when I rebuilt the transmission I replaced the driven gear with what was supposed to be correct for my tire size and gear ratio, and now it’s about 10 mph off and bounces a little bit. Could the cable just need lubed? I can’t hear it if it’s making noise, the truck is too loud.
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Last edited by 70STOVEBOLT; 07-09-2021 at 03:37 PM.
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