My speedometer isn't working!

[NRS13]

since I bought my car, the speedometer has not worked. I was wondering if anyone could tell me what might be wrong. The car is a 1990 fastback. In addition, when driving in the rain a couple of times, when going over big bumps, the speedometer would work for a moment, then go dead again. Sometimes when I'm accelerating fast and at high RPMs, the needle creeps up and then falls down the other side. At this point, it is buried on the right, past 120 and all that. So, I don't know if a sensor is bad, or if it is just a bad connection. Any help would be appreciated. Thanks.
-Reed

[nsn240]

mine does the exact same thing, pretty sure the speed sensor is dead... but for me it only happens when i havent driven the car for a couple days. I started jumping around last night when i was going ~95mph for a couple miles. I have another sensor if you want it... going up over bumps is just because the needle is really light/sensitive

[rossfashow]

i want your sensor!