On my way to the dmv just now, hit a speed bump and now when the Speedo goes over 45 it goes all over the place but when it drops to 45 or below it's fine. Going to check it out tonight, just wondering if it sounds like the gauge went or cable is going. Never had one go out where it only worked half of the gauge

 

Sounds like the cable is sticky and binding. Ever look at the inside of the cable? It looks like LONG little tight wound spring. That's so it can bend and flex and still rotate. What happens is when it drags, it kinda builds up some tension inside, then when it does finally move, the tension releases and the speedo needle jumps wildly.

 

Yeah I figured. I got back in it and it's working fine. Off to autozone lol

 

Mine was doing that.....and I removed the cable from the outer jacket and sprayed the bejesus out of it with white lithium grease and put it all back together and no more bouncy needle. I did this about 6yrs ago. Works great.