does anyone know how the speedometer gaugae works?

[dafrompa]

Just was woundering if any has ever had this problem and how they solved it and wanting to know how the speedometer gaugae works altogther or just what are the componets involed to make it work. Well anyways my speedometer gaugae has gone hey wire what i mean is one time i'll start my car up and go down the road and it will be working fine and other times it will just go hey wire like I'll start my car and it looks go so far but then it will jump up to 140 and I'll stop and will take for ever to get back down to 0.

[gijonas]

You probably need a new cable.

[BSOD2600]

There is a thread somewhere on here were I took it apart and lots of pictures... it's quite the little mechanical device, that's for sure.

If it takes forever to return back to 0, that means the spring steel coil loop around the shaft has gotten really weak or broke. Showing 140 mph would suggest there is dirt between the two spinning disks (speedo cable and speedometer needle) or something else causing friction. It normally moves due to the spinning magnetic forces.

[Potter]

If you take the cable out and just put it in some oil, that should fix it if the cable isn't broken