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I've been unable to find an answer in the Search Function so here is my problem.


Speedometer needle has started fluctuationing all over once my speed exceeds 50 mph.  Below that speed the needle moves in a linear motion consistent with speed, but once I exceed 50 mph the needle jumps up to around 70-80 mph and jumps all over the place.   


To get it to return to the lower ranges my speed has to be below about 20 mph.  The speedometer was completely gone thru and rebuilt seven years ago by the Germans at West L.A. Automotive Center/Speedometer Plus and has performed flawlessly ever since, though it has been reading somewhat high at highway speeds since I went from the 195/60 x 14 tires that they used when they recalibrated the speedo to 185/60 x 14 tires now.


What might be causing the wild fluctuation of the needle when I get above 50 mph.  With the speedo right in front of my eyes the jumping needle is distracting and a little irritating.


The car is a Chamonix '75 with an automatic tranny.  The speedometer plastic gear drive (at the rear of the tranny) was replaced with a metal one from a '73 automatic about a year ago in order to eliminate the leak at that area.  It worked fine until the fluctuation began yesterday.




Bob Napier


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One possibility is that the cable is not spinning freely, causing fluctuations in the spin rate of the speedo end of the cable. You may want to pull, clean and relubricate the cable (or replace if you see noticable wear in any spot). I believe there is special lube made for speedo cables.

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As far as lubing a speedo cable, I remove the cable and clean it in mineral spirits or some other kind of solvent. I then clean the casing with some type of spray cleaner like brake cleaner; something that won't leave residue behind.

I then smear lube onto the cable, leaving 6" or so of the speed end free of lube. Thread the cable into the clean casing and re-connect.



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And if you're less ambitious, and I'm speaking from experience here, you disconnect both ends of the speedo cable and you just keep pumping speedo cable lubricant into the top end of the cable. It eventually works its way down as long as the lower end is disconnected.

I forget, Bob, if either of your cars was originally equipped with a thermal reactor; if so, you have two shorter speedo cables, feeding your speedo through the widget that triggers the thermal reactor warning light. cd believes -- and he may certainly be correct -- that some cars without thermal reactors nonetheless had the widget, and hence the dual cable arrangement.


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Bob, that sounds like the same problem I've had with the speedo on my '73, and it's internal to the speedo, not the cable.  If the cable was binding, the needle would twitch at almost all speeds, not just above 50 mph.  I'll bet the twitching will gradually get lower and lower on the speed scale. 


Drop me an e-mail and I'll send you the column I did on fixing this problem.  It takes longer to remove the speedo head than it does to fix the problem. 




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I'd bet on Mike's fix. Took my speedo out last night to fix major twitching and odo stopping. Accomplished both without any previous speedo experience or instructions. Just patience and pretty good mechanical instincts. ( I like to fix things) plus these great little German cars are well designed. If needed, I will be happy to share what I did.

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  • 9 months later...

Bringing this back since I have a kind of similar issue.


My speedo is just going nutty. I finally got it working and put in the long speedo cable for the 5 speed swap a week ago. It worked great, although there seemed to be a dead spot from 45-50mph where it didn't move. I was okay with that.


Now, it's gone all wacky. Moving the car (even just letting it roll forward a tiny bit) and the speedo jumps to 60, or really any random spot it seems. When driving it is just going nuts, all over the place. It usually says above 100 though. Is this a broken return spring?



This happened RIGHT after I removed my A/C unit, is there any electrical aspect to this gauge? Does it use a ground? It seems quite odd that it happened immediately after I removed my A/C unit under the dash.


I don't think I bumped anything, but maybe I did. Surely it couldn't be more than the bumps I feel on the road.


If it is a bad return spring, are these things serviceable?

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