I just changed my speedo cable on my 65 Coupe and now when Im driving it acts really crazy. The speed is in the general area but the needle is wobbling all over. Say Im driving 58, the needle will be bouncing between 55 and 60. Any ideas, this is my first Mustang. Thanks

 

There may be a technical answer to this, mabe not. Remember, the car is old. My '71 f-250 speedo basically acted as a 'ballpark' meter as you've described.

However, that was a different speedometer design. My Mustang's seems to work fine :-/

 

The cable is most likely binding a little inside the casing. Did you change the entire speedo cable and housing or just insert a new cable? Suggest you disconnect it from the tranny, pull the cable out of the housing, and lube it with lithium grease. Auto parts stores actually sell a grease for this.

Also ensure the cable housing had no kinks, binds, cracks or holes in it.

 

Good News!!! I pulled the new cable and housing out to take a closer look and noticed that it's about 6 inches longer than the original. So I took the original cable out of the housing and gave it some a good lube job, reinstalled that in it works perfect. No jumping needleandNO DASH NOISE. Which is why I changed it in the first place.

 

I gave up on my speedo problems. After the original cable snapped I have broken two speedometers. I have the cable lubed up and am using the orginal gear. My odometer works fine but the needle just flys around in circles and makes annoying sounds[:@]