My speedometer ('87) was dead below 30 mph and then would spring to life and work properly. The odometer has always worked right.
I found this and replaced the $70 sensor:
http://forums.pelicanparts.com/uploads15/G50impulse1248984991.jpg
I still had problems. The speedometer would come to life at lower speed, but then would operate erratically with no real relation to actual speed.
I figure the problem must be within the speedometer so I sent it off to North Hollywood Speedometer, along with $147.
I reinstalled it and now the needle bounces below 20 and registers erratically above that, generally settling around 40 mph regardless of speed.
What do I look at next? Dirty or missing magnets possibly? How many magnets do the G50's use? I know that earlier transmissions use eight. Any tricks to getting them clean without disassembly?
Thank you.