speedometer jump - needs calibration

[kevin_tbird]

my speedometer is very touchy. The readings jump around a lot. It reads high by at least 20MPH.

The speedometer does read higher as I go faster. There is a new driven gear and drive gear (I'm pretty sure I have the right ones) and a new cable.

Why is the speedometer so jittery? Could I have a magnet problem in the speedo?

Kevin

[simplyconnected]

Jumpy speedo is usually caused by the cable getting snagged in the cable armor. The inner cable gets snagged, then goes fast once it frees, over and over. You may need a new cable assembly.

Correct speedo readings are caused by a combination of proper speedometer gear and correct tire height. - Dave

[Guest]

If your cable and speedo gears are new then try another speedo head. That cured my speedo bounce.

Have a good day, Gary

[kevin_tbird]

I checked the cable and found no tight bends. Thr interior cable has no marks or rough point. Lubrication with graphite helped, but did not solve the bounce. My biggest concern is that the speedo bottoms at about 15 mph when the car is not moving. Is the zero point adjustable?

[LuckyJay]

The inside of the speedo housing needs to be inspected for any foreign objects. Even a very small iron filing in the wrong place can cause what you've described.

[lawyercalif]

I dont know if it is the correct way, but I just moved mine to zero with my finger.