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Jumpy Speedometer
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Author:  darwigger [ Wed Jul 09, 2014 1:04 pm ]
Post subject:  Jumpy Speedometer
Hello,

Been fighting a jumpy speedometer. I pulled the cluster out and had it rebuilt; still clicks and jumps, (although quiteter, still in the same spots). Also started with the cable of course. Haven't gotten a new one; but have completely pulled out the old one and lubricated it with anti seize stuff. It looks fine, I can't imagine anything being wrong with it. Speedo jumps more at certain speeds than others. (around 40 mph the worst).

Now what? Could it be at the tranny? Or get a new speedo cable and try that. Had a bit of a problem finding one though.

Any help would be appreciated,

Thanks!

Dan
Author:  wjajr [ Wed Jul 09, 2014 2:26 pm ]
Post subject: 
Most likely cable is still fetching up in its casing somewhere. Like any rotating device it has harmonic points where the cable will cavatate (sp?).

I would get a new cable ASAP before the rebuilt head gets trashed.
Author:  darwigger [ Thu Jul 10, 2014 7:28 am ]
Post subject: 
Thanks wjajr! I will begin the search for a new cable. That makes sense, that's where I was headed.
Author:  slantvaliant [ Sun Jul 20, 2014 12:03 pm ]
Post subject: 
I'm going a few rounds with my speedometer. The needle got jumpy, so I cleaned and relubed the cable. No dice. It seems the sheath had worn in two about a foot from the transmission end. So I got a new one from Imperial Services. Problem solved? Nope. Still jumpy over about 10MPH.

Thinking it might be the meter itself, I tried spinning what's left of the old cable with a 3/8" variable speed reversible drill. With the cable in a nice large-radius curve, the needle moved smoothly. By the way, my B&D drill is good for just short of 90MPH. So ... it is not in the meter. Cable/sheath binding, perhaps because of a too-sharp bend.

I tried rerouting the cable to reduce binding. That seems to have helped a little. The jumping doesn't start until 20MPH now. :cry:

Time to go back and hit it another lick or two.
Author:  mpgFanatic [ Sun Jul 20, 2014 3:31 pm ]
Post subject:  inner core still flexible?
Quote:
The needle got jumpy, so [....]
Assuming that it used to be smooth, and assuming that you initially followed the same cable routing that had been there for years....

Your scientific approach is good-- I think you've narrowed it down to a too-sharp bend for that cable. Have you talked to Imperial Svcs about their replacement product? They surely must have heard of these issues before.

Another thing I always wonder about is how long a cable has been coiled up on a shelf, where the core might "take a set". If you pull out the core, is it flexible enough that it decides to pretty much straighten by itself? If not, I could totally imagine it whipping around as it doesn't want to flex. I have never actually seen this problem, but can imagine it.

- Erik
Author:  Pierre [ Sat Jul 26, 2014 5:32 pm ]
Post subject: 
Watch the angle the cable enters the speedo at. If this isn't dead on it will cause the speedo bushings to bind and this will happen. If you push it to one side or the other it may help.
Author:  Doctor Dodge [ Sun Jul 27, 2014 7:50 am ]
Post subject: 
Other "tips"...
Use dry graphite as a lubricant not any oil based products. Clean the housing and cable with carb cleaner and "powder" it with graphite.

Along with straight entry, check to be sure the cable ends are square and "deburred, and not a "little long"... poor end termination or excess length can cause the jumping... especially ant the speedo end.
DD
Author:  mpgFanatic [ Mon Jul 28, 2014 7:34 pm ]
Post subject: 
Quote:
excess length can cause the jumping...
+1. Good call, Doug.

I forgot about that problem... years ago, I purchased a generic cable insert that had to be cut to length to fit into the old sheath, so decided to err on the side of caution... that a tiny bit long must be better than a tiny bit short. Nope! It binds in the sheath.

You can test this theory by loosening the cable at the speedo head a tiny bit, as if you're going to disconnect it from the speedo, but don't let it disengage entirely. Very easy to do on the older (1967-older?) screw-on style, but should be possible on the newer snap-on style as well.

I'd put the rear end on jack stands and let it idle in high gear at a speed where you know the needle jumps, then see if it changes as you loosen the cable behind the speedo head.

- Erik

PS. I used to be able to use "1968" and "new" in the same sentence without laughing..... :D
Author:  darwigger [ Wed Oct 15, 2014 8:16 am ]
Post subject:  Speedo Update
Thanks for all the suggestion fellas, really appreciate it. I did end up getting a new cable from Imperial Services. It took 'em forever, but it fit and was shiny and new. I installed it and guess what? The needle doesn't jump anymore! But, now it's noisy as hell. Makes a steady graiting kind of sound (if that makes any sense) that it didn't make before. It's pretty darn loud. Anybody run accross that before? I guess my next option would be pull the cluster back out and see if it's from the cable or something in the cluster. And try lubricating the end with graphite maybe?
Author:  SlantSixDan [ Wed Oct 15, 2014 12:11 pm ]
Post subject: 
Did you lube the new cable before installing it? That's necessary. See here
Author:  darwigger [ Tue Oct 21, 2014 8:07 am ]
Post subject: 
Yep, it had been lubed with some anti-bind stuff. Pulled her out and tried some graphite as suggested and guess what, it worked! Noise is gone! But, now it jumps again. But it wasn't jumping the first time the new cable was installed; so I'm thinking it's at the speedo end as suggested before in this string. I'll play around with that next; maybe i didn't get it dead on; hopefully it's not a little too long; I'd be afraid to cut it.
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