Speedometer problem
 

I have a 91 Miata with 91000 mi but the speedometer has started to make a lot of noise and bounce I thought it may be the cable so I replaced it that didn't fix it. I called speedometer shops only to find out they don't rebuild them can't get the parts. So now I'm not sure what to do? If I buy a used one they usually have alot more miles so won't last long. Has anyone had this problem and fixed it?

Miata speedometers are not known to fail. Cables wear inside the sheath and can bind and release causing needle fluctuations. If your new cable was ever kinked or even just curved too tightly it will bind and release similarly instead of spinning at an even pace. If you dislocate both ends of the cable and rotate the signal wire between your fingers it should turn freely with no resistance.

The speedometer is merely an electric generator spun by the cable and a meter to measure its output. They usually either work or they don't.

Good luck.

My Miata chirps in sync with the speedometer. I was told by the seller that he was told many years ago it is the cable causing the problem. It stops chirping once I hit about 50 and sometimes it does not chirp at all. My car is old a 1992 I just purchased it and it runs great but that chirp can be annoying. What do you think?

Speedometer Problem
 

Thanks for the info but the new cable it free so I guess I have a bad speedometer. One speedometer shop said they could lube it and that should help. What do you think?

That is the cable. If you change it, the noise should go away.

You could do it yourself just the same, I would think.

Speedometer
 

I.ve got the same issue on my 94. My repair manual says the wheel has to come of to access the back of the speedometer, is that accurate. What would you use to lubricate he cable. How dangerous is the air bag if I take of the wheel with a disconected negative terminal.

Oh thanks so much. There is a video on youtube we looked at that showed how to do it. I am not mechanically inclined so I will most likely take it in to have it done. My son may try to tackle if but I'm afraid of what might go wrong..Thanks again for your answer.

The wheel does not need to be removed to remove the speedometer. It didn't on my '96 which is identical to your '94.