Hi Everyone, First let me say I did read all the posts on this subject. I still have a few questions on some of the procedures that aren't entirely clear on the steps to do this. I have a new to me 1980 RX-7 and the speedometer has stared to make a slight noise and the needle will vibrate a bit. Now it will occasionally make a loud sound and the speed reading will double and then go back to normal. I believe the cable needs cleaned and lubed. My questions are:
1- That I can remove just the cable from the bottom, Trans end.
2- Do I need to un clip the clip from behind the speedo before I pull out cable from Trans end.
3- Tri Flow would be best lube?
4- The speedo end has to "re seat" into clip end and best to test with drill motor before re attach trans end.
Thanks,
Mike
1980 RX-7 times 2.

 

I used to work in a speedo shop!
1. As I recall, yes, the cable will come out from the bottom. Asian and European cars worked like this. Apply even pressure when you remove it.
2. When you reinstall the lubed cable it should re-seat into the speedometer. You will be able to tell by how much of the cable protrudes at the bottom. Also, spinning the cable counter clockwise should make the the needle jump in the speedometer. If you can't get this to work, you may need to take the cable housing off of the instrument
3. We used a light grease on speedo cables. It had allot of oil in it so it never dried out like a lithium grease will tend to do. No graphite or speedo-lube with graphite!
3A. Test the cable for kinks before you clean it and lube. To do this hold the cable in a U shape with your hands at a shoulder width and roll the cable back in forth in your fingers. It should not bind or snap in your fingers. It is does, it has a kink and has to be replaced.
4. You can use a drill set to reverse to test a speedometer. But using your fingers works too.

This is a good first thing to do but this issue way be in the instrument itself. There are two bearings that supports the needle shaft - one in instrument frame and one in the center of the magnet - that can get dry and cause this. If the cable lube doesn't solve this, the instrument will need to be serviced.

 

And don't try to fix it yourself, the speedo mechanism is a very precise analog instrument and can be easily damaged if you try to take it apart and mess with it. Ask me how I know!