I’ve owned my 68 convertible for just 3 years now. Since I got it, I noticed that the speedo needle would wobble slightly at speeds between 50 and 60. It was fairly minor and stable above and below those speeds. Until about a month or so ago, when the wobble got more pronounced - swinging 5+ mph. Again, only around the same speed. A couple of drives later it got worse again - swinging 10 mph or so (again in the same neighborhood speed-wise).
I was planning to lube the cable in the spring when I get it out for the season next year.
But, I took it out last weekend for a final drive before winter hibernation and the speedo suddenly went crazy! It is fine to about 30 mph, but then starts to swing wildly, even past the 160 mark. This time, though, I heard a whirring/grinding sound from the dash. I immediately took it home.
Any thoughts on what would cause that? Seems like more than a cable needing lubrication to me.
Few things come to mind. First of all you did the right thing lubing it. Next thing you can do is check the plastic gear on the transmission side. If that checks out, replace the speedo cable. I don't believe there is anything you can do on the instrument cluster end.
Remove the cable from the back of the speedo housing and pull the inner cable out, wipe it down and inspect it for any flaws, lube it up as you install it, and drive it again to see if that fixes it. More than likely that will be all that is wrong. Need to keep them lubed as soon as they start to act up, if you let it go too long it can strip the plastic gears in the trans trying to turn the cable.
Thanks. I put the car down for its long winter hibernation and figured I’d deal with it in the spring. Hopefully you’re right that lubing (or replacing) the cable does the trick. It just worries me that the sound was coming from the dash. Hopefully it is one of those cases of the sound transmitting.
Have the same problem with mine. When I started to drive her after years of sitting, the speedo would bounce between 30 and 120 MPH! I lubed it but it only helped a bit. Hoping just replacing the inner cable will do the trick. Much easier than changing the cable housing. Fingers crossed.