Title says it all - Speedometer is howling like a mofo'. Replaced the speedometer cable with a known decent one and it makes a wretched howling noise and I can't see the needle (its an 81 GL, that has the "arm" that goes out to the center of the speedometer - is the needle behind that???)

 

Basically do I need to replace the speedo- or is there something else going on???

 

- Erik - Tacoma, WA -

same thing happend to my 81. Eventually the needle broke off.

 

Not sure if you know how a speedometer works. But there is a magnet attached to the end of the speedometer inside the dash and a metal cup that is mounted very close to this magnet this cup is also connected to the gauge needle. When the speedometer cable turns fast it makes the metal cup want to turn by the force of an eddy current in the magnetic field. A spring opposes this force so the needle doesn't spin freely.

 

So what happens is as you can guess the tolerance between the magnet and the cup is very small. After about 1 Zillion rotations the support bearing gets a little worn and then the magnet can contact metal cup and presto lotsa noise and your subi is doing 85mph. I fixed mine by getting a new dash out of the junk yard but eventually it did it too. Another option is to just disconnect the speedo cable untill you find a suitable replacement. Just reach up behind the dash and pull it out. Sorry for the long winded post.