Volt meter and speedometer not working????

[ebk06]

In my 87 lx the stock voltage hasnt worked since I got the car. When I start it is shoots right up to the highest reading. I replaced the cluster for other reasons and this one does the same thing. It cant be right because I've had the car for a while with no charging problems but I have no idea how to fix this. I know its not a big deal but I hate seeing it shoot right up all the time.
Next I replaced my speedo cable (old cable was melted through) and VSS sensor this weekend and it smoothed out the the speedometer a little but it still climbs way to fast and shows me going 85+ when im only doing about 50. Im guessing it the cluster since my old clusters speedo worked fine until the cable melted but just want to make sureI'm no missing something?

 

[jrichker]

Put a digtial voltmeter across the battery while the engine is running at 1200 RPM. If you see more that 14.5 volts, you have a voltage regulator problem. All 86 and later Mustangs used an alternator with the voltage regulator buit into it. The exception to this rule is the SSI police/highway patrol cars, which may have an exteral regulator.

Your rear end gear ratio may be other than stock. That would make the speedometer read faster than you are actually going. Jack up the car and turn the rear wheel one turn and cout the number of turns the driveshaft makes. Stock gears were 2.73 or 3.08. Possible replacement gears are 3.23, 3.55, 3.73, 3.90, and 4.10. A different driven gear on the speedo cable changes the calibration of the speedometer.