Speedometer not working

[jhonda]

I just bought a 91 mustang lx. It has the 140mph speedO but all it does as soon as you start to move is bounce around 80mph to 0 then to 120 to 0....etc Does anyone know what the problem is? I have been told that it could be the transmission gear that hooks up to the speedO, or since the odometer works but the tripometer does'nt it could be the gear that connects behind the dash. Any one had this problem or how to solve it, if so how much money.
Thanks Jason

 

[C6AE]

My LX did that after I moved the speedo cable to put a clutch pedal in. there was a magnet that drives the needle and it was getting hung up, made a slight ringing noise on occasion also. Bought a new gage cluster and it's good now.

 

[86bluecobra]

I would first suspect the speedo gear. Crawl under your car and remove the speedo cable and gear from the tranny. Odds are it is stripped. It is only held in by 1 bolt. You will be able to see if thats the problem right away or not.

 

[KcMstang]

Check the connection behind the dash! The sensor in the transmission and if the plastic gear still looks good try spinning the cable itself to see if you can get the speedo to move then try to pull it out to make sure that it isn't broken.