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I have a mid-90s econobox which still has a mechanical speedometer.

In cold weather (sub-50F/10C) the speedometer will sound really squeaky, and above a certain speed (30-60 depending on cold) the needle will leap to 1.5x, 2x or 3x actual speed while making a terrible grinding noise. Slowing well below that speed will cause it to calm down.

I work with the speedo cable regularly, and I have positively eliminated the speedo cable - that's not it.

It appears to be that the lubricant in the speedo has broken down /no longer finctions in cold weather.

I have torn down speedos before, so I know the drill. But I have no earthly idea which lubricant I should be using. I'd like this repair to last awhile. Any ideas?

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  • Does the speedo bounce at the higher speeds (when it's doing what you're talking about)? By bounce, I mean does it dip to a lower speed, then to the high speed, then back down to the lower speed even if you know the vehicle speed is constant. Oct 30 '17 at 20:16
  • Yes, as it enters that state, it's a warning sign for me to slow down or else. I have eliminated the speedo cable. Oct 31 '17 at 0:39
  • @paulster2 what I mean is it will wobble up and down as it approaches the speed at which it leaps to pointing to double speed (no wobble at this point) Once it goes to double speed, it will do it for an hour, eventually stopping when the speedo warms up from running the heater. Once it is thoroughly warm it behaves. However it starts all over again the next day. I've swapped the speedo cables several times, and none of them have amy kinks or evidence of unusual wear. (The cable core comes out of the sheath so it is easy to lube and inspect.) Oct 31 '17 at 4:29
  • Fair enough. Like Solar Mike said, then. Oct 31 '17 at 4:32
  • Perhaps WD40? Lol Nov 1 '17 at 20:33
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A good quality fine oil - we used sewing machine oil... definitely not 10W40....

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  • I put a few drops of 3-in-1 oil around the input shaft to the speedo (teardown of same revealed no useful lube points other than that. It was turning stiffly when I started, and freewheeled nicely after I spun it a few hundred times with a screwdrriver oriented so the oil would work downward. A stint in the freezer and it came out fairly free also. Initial road trip revealed symptom gone, but it still flutters, haven't been able to test it at speed or in real cold. Know tomorrow morning. Oct 31 '17 at 0:42

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