Speedo is “jumpy”

31 Woody

31 Woody

Senior Member
Speedo is “jumpy”

A week ago I had the dash out due to a popout switch issue. This means I disconnected the speedometer. We drove the car on Sunday and the speedometer was jumping up and down a range of 10+ MPH from whatever speed I was going. Did I not get the cable in properly? With the extra gauges I have, it sure sucked trying to get it back together, but I can take it apart if needed. I can’t have the speedo jumping all over the place! Thoughts on the problem?
 
Re: Speedo is “jumpy”

If it was registering smoothly before you removed the dash you have a clue. Have you ever lubed the speedo cable? I am sure you already have felt and visually inspected the cable routing for kinks. You would have to really bend it hard to kink the inner cable. Did you have to "bend" it out of the way to get the dash off?
I chased that same rabbit for a few weeks and ended up getting a new cable from Mikes, which was much "stouter" the the old one. My speedo was so "bouncy" that I purchased a rebuilt unit from Bert's.
Even so, I checked the accuracy of the new speedo using a GPS app on my phone and found out that it was reading about 3 mph slow. At least I don't have to chase that same rabbit for awhile. Chap
 
Re: Speedo is “jumpy”

I had the same problem but also noise,removed the plug from the back of the speedo cleaned out the dried out grease and packed it with lubriplate,good again.
 
Re: Speedo is “jumpy”

My issue was an ammeter problem, but, pulling the dash did something to kink something or ?? Also found under the car at the transmission, the cable wrapped with friction tape! Bit the bullet, bought a new speedometer cable and lubricated properly and installed and no more jumping!
 
Re: Speedo is “jumpy”

I agree. Somewhere the cable is kinked, maybe not much but it is. I would remove the inside cable, clean it and as DZ mentioned use some lubriplate on it.

I have had good luck with AGS.
 

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Re: Speedo is “jumpy”

You can over tighten the cable where it goes into speedometer. If it is to tight, the cable is pressing to hard against inner drive and will effect how the speedometer reacts. It will jump around especially at slow speeds. Should only be hand tight. Enjoy.
 
Re: Speedo is “jumpy”

Test the input of the speedometer, it should spin easily with the tips of your fingers. any tighter than that will wind up the cable like a long spring, causing the speedometer to swing wildly.
 
Re: Speedo is “jumpy”

Thanks for all of the reply’s and suggestions. I will dig into it this weekend and figure out what I did wrong.
 
Re: Speedo is “jumpy”

How did you make out with this issue?
My speedo was jumping all over the place then pegged at zero. I could hear the cable banging around for a bit then it stopped and speedo started working again for a bit.
If you take the cover plate on the dash off does that expose all of the workings underneath?
 
Re: Speedo is “jumpy”

Mine did that when I 1st pulled it out of a long storage. Had a bunch of things done to my truck at a shop including this issue. Was told that since it sat too long the cable and speedo lube had hardened, causing the gears on in the turtle to wear/strip, and they also had to service the speedometer and re-lube it. I do not know how often you are supposed to to lube the cable once it is good/working.
 
Re: Speedo is “jumpy”

I removed the lead seal on the speedometer housing (after much thought) and carefully dis assembled the unit on a clean towel.. making note of each part and location. The lube had hardened and caused the small gears to not mesh properly. Cleaned, reassembled and lubed ... unit now works like it should.
Ha... I knew I could do it..!! :) Careful of the small spring..!
 
Re: Speedo is “jumpy”

You’re welcome. I am sure life and kids have never altered anyone’s best intentions and plans. By the way, despite attempting several of the above ‘remedies’, it still jumps.
 
Re: Speedo is “jumpy”

If you have not tried it, perhaps time for a new cable. Could be the old one is full of rust/crap/dried lube. To trouble shut find an old cable, cut it short, and use a variable speed drill to drive the speedometer. If OK you know the speedometer is OK.
 
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