jumping speedometer

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cantcatch06

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Speedometer started jumping while drive down the road. At first it was only at freeway speeds and progressivly got worse. Removed speedometer cable and lubricated with powedered graphite. Same jumping problem as before. On way to work the next morning halfway there started jumping Excessivly then the needle broke off, Broken part of needle jumping even worse then before for another mile then nothing. Remove speed cable and replace with new one, old one was twisted off near the transmission. Removed speedometer and replaced with a spare from a busted cluster from another car. Carefully cleaned by hand, lubed, polished etc.. On way to work this morning noticed a slight shimmy at speed less than 5 miles total fluctuation. Figured it was just a sticky cable because it was new. At lunch more graphite in cable. On way home same road as before... same thing happened. Starts jumping BAD then the needle breaks off. Less than 5 min passed between when it started jumping the second time and the needle breaking off..

My question:
is it possible i've got a bad speedometer gear causing my problems?
Also has anyone had any luck fixing a broken needle?
If not any guess where to find a speedometer for a 66 barracuda?
 
You can fix the needle with some glue and a carefully trimmed piece of paper-keep it light so as to not throw off the balance much. repaint speedo needle with some model makers paint. You might have a bad speedo gear or it might not be fully engaged on the output shaft-it is on a eccentric. I have found on some cables that twitch after clean/lube that it was a routing problem that caused the twitch.
 
A jumping needle is (most of the time) NOT in the instrument, but in the cable or gears

Your cable liner may be damaged inside or "under a strain. There is almost no possible way to tell if the cable liner is bad--unless maybe you have a fiber camera that small.

It MAY by routed so that it's strained, try pulling it out and relaxing it, putting it back in--the jacket that is.

You might be able to get a clue as to whether the cable jacket is damaged by carefully inspecting the inner cable, then run the speedo with a drill at the transmission end and have someone watch it.

Pull the speedo gear out of the transmission, inspect for damage, and check the "bushing" what would be the gear shaft for wear, and inspect the mainshaft gear for damage, dirt/ debri.

Make sure the cable is properly lubed I would NOT use powdered graphite

The only thing the shop manual gives is a Chrysler no, not a common spec. I believe originally it was a graphite impregneted light grease
 
the speedo needle did not hit the stop because the 66 doesn't have one. So it should be possible to fix the needle as long as it doesn't get too heavy. I was thinking super glue and some construction paper, and the model paint should work well for repainting it so you can;t tell it was broken.
 
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