legacycentral bbs

hey everyone, the speedo needle and the odometer stopped working all of a sudden on my 1990 GT wagon. nows the last time i recall it working was just before i installed the boost gauge. the feed it took off for the boost gauge is from Teeing into the blow off valve's vacuum line that runs back to the intake. but i somehow dont see how installing a boost gauge would affect the speedo though. but just before it died, the speedo needle was jumping mad before it laid to rest. now couple things i need to know, is speedo feed done by cable or by electric feed and how does it hook up to the gearbox, is it screwed in or just pushed in like a plug? more like i need a replacement instrument cluster or is there a speedo cable that needs replacing? cheers

Either your speedo cable came undone or your VSS is gone. If you do a search, you'll find threads about fixing both.

Is your car MT or AT?

Very recent thread for speedo cable replacement: http://bbs.legacycentral.org/viewtopic.php?t=29825

There are some of us here who have a different source of the same problem. There is a plastic part in the transmission that drives the cable. If it breaks, the transmission needs to be removed and nearly completely disassembled to replace the $13.00 part.
You can check for this pretty easily. Unplug the speedometer cable from the transmission end. Attach a hand drill to the cable shaft and spin it; slowly at first. If the speedo responds, then the cable is probably OK. Obviously, it would be more promising if it doesn't respond, and it's only the cable that's broken.