I just installed a z28 gauge cluster into my 1992 RS and the speedometer is not working correctlty. The speedometer acts as if it was my original speedometer that only went to 110 with a 145 mph face on it. For example when it says I am going 80 I am actualley going somerwer around 60.

Do I need to have something else re-callibrated for the new speedometer to read the correct speed?

Or I am I experiencing this problem because I fried the little green board near the speedometer and had to replace it with the one from my old gauge cluster.

I really dont know so if you can help it would be appreciated.