MGB mgb speedometer is erratic

[GBT]

I have a 1980 mgb with a twitchy, erratic speedometer. the needle jumps all over and is not steady at any speed. don't know if this is a cable or a speedo drive problem, or both. as this is my first attempt to ask for information I hope this is acceptable and appreciate your help

 

[David_DuBois]

I fought with that same problem for years on our 66 MGB. I finally gave up and installed a GPS speedometer that I got from Speedhut https://www.speedhut.com/
Cheers,

 

[borjis]

another thumbs up for speedhut guages.

replaced both tach and speedo on my '72 (so they match)

money well spent.