Just picked up a Z with a strange rattling/grinding noise coming from the cluster, P.O says it's the speedo cable "rattling" when I asked him during the test drive. Though the sound is annoying, it seems like this issue might be affecting the accuracy of the speedo.

When we first hit it on the freeway, the speedo was barely climbing from 35 to 50 MPH so i initially thought "Wow, auto Z's are pretty slow after all..." However we were blowing past cars like crazy. Got out my GPS app which shows speed via sattelite tracking, and when the speedo told us we were going 54, the app was telling us we were going 78... And at 75, the app told us 108...

So my question for you guys: Is the speedo cable sticking? The car sat in the sun for years, so coudl lubricating the cable fix it? Or will it need to be replaced? (We are on a very tight budget) Car has 125K miles.

 

Yes, the usual culprit is the speedo cable. Though it's usually because it's been kinked or bent at the frame rail due to bottoming out the car. I have seen several fried speedometers, but I'd say from tinkering.

Inspect and you'll know.

 

Took a look at the lower speedo cable, and though it didn't look damaged, it was loose from one if it's clips. Do you think the grinding/squeaking might be from the speedo itself? Another thing to note is that the needle doesn't sway much like one would expect.