Insulate the speedometer cluster, there's too much electrical "noise" surrounding it. That causes the signals to get confused; happens on all fords and AMCs that I know over time.
The instrument cluster is what houses the speedometer, and the gauges.
First check the speedometer cable going into the top of the transmission. If it is not broken the instrument cluster must be replaced.
It is in the instrument cluster in the dash.
you have to take out the intrument cluster and replaced the light bulbs that are inside the instrument cluster!...its really simple
We had the same problem, and our 1998 F150 needed a new instrument cluster.
The speedometer is part of the instrument cluster, and is fused with the other instruments.
It is the center gauge in the instrument cluster.
Dashboard area where guages, speedometer, & lights are located
Nothing
An instrument cluster is what displays basic information in your car. Information like the speedometer, fuel level, care temperatures... etc. Cars nowadays are mostly made with a digital instrument cluster.
The speedometer itself will work but you will need to take the instrument cluster apart and transplant the speedometer unit from the 92 cluster into the 87 cluster. The speedo mechanism is the same but the clusters are different.
You have to replace the entire instrument cluster.