Why does the speedometer in my 88 acura legend jump?

Question

It doesn't jump to random numbers but it just jumps as the car moves. its stays around the right speed im going but it just jumps up and down(like if im driving 55mph it will bounce between 50 and 55) what could be causing this because the car runs smooth. is it a problem in the dash or something?

Answer 1

It's the speedometer cable.

Answer 2

Lube the cable.

Answer 3

Three options:

a binding speedometer cable.  Trace it from the transmission and look for any kinks, melted spots, worn locations etc.  This is the most likely.  Easy and simple remove the cable from the tranny and the back of your dashboard and reinstall in reverse.

Your speedometer gears have stripped one or two teeth and miss then grab miss then grab etc.  More expensive to replace than it's probably worth

Or your drive gears in the transmission are worn or the incorrect size.  Ive seen this happen many times on used and rebuilt transmissions when the incorrect gears are placed in the tranny.  Easy cheap fix with some knowledge of trannsmissions.

Good luck.