1990-1997 Miatas use a mechanical speedometer cable that is spun by the transmission and routes through the engine bay to the back of the gauge cluster. These cables wear out over time and there is not a reliable way to re-lubricate them. A dying speedometer cable makes the speedometer shaky and twitchy, with a new squealing sound of the cable spinning.
Mazda OEM Part Number: NA01-60-070B
The game plan for replacing the old speedometer cable is.
1. Remove the gauge hood (it will probably shatter and need to be replaced)
2. Detach the gauge cluster from the dashboard and pull it out far enough to unclip the old speedo cable
3. Tape a wire to the old cable that will be used to pull the new one back through
4. Release the clips holding the old cable to the car on the firewall behind the engine and in the transmission tunnel
5. Unscrew the old cable from the transmission
6. Attach the new cable to the transmission and feed it back through to the back of the dashboard
7. Re-attach the tabs, clips, and grommets that hold the cable and gauge cluster
The cable connector rotates pretty easily, spin it around until the clip on one side is accessible to detach it.
The connection to the transmission should not be too tight. Use a pair of pliers to loosen the grooved nut. The spinning end of the cable fits into a slot in the transmission, don’t force it.
|Speedometer Cable NA01-60-070B