OK here's the deal. On my '96 GT the tachometer isn't reading right at idle. When there is no throttle at all, the tach reads between 100-200 RPM, which is obviously not right. The car is running fine and I know it's idling as it should, so I'm guessing the needle mechanism is not working right. When I give it just a little bit of throttle, the needle jumps right to about 700-800 RPM and from then on it reads right while driving normally. Then at idle again, the needle slowly drops down and at about 700 RPM it drops right down to about 100-200 again. I'm not sure about how the actual needle is manipulated so I'm not sure how to troubleshoot it. I'm guessing if it's driven by a gear inside the gauge it might just be stripped or something. Any ideas?

 

Stock gauges suck. the tach isn't accurate to begin with, it may just be dying. You could change out the cluster for one from a wrecked car, or get a whole new cluster for autometer with the lunar faces.

Maybe a.....Ricebowl????

 

Haha! I'll just skip right on down to Autozone and get one of those off brand bright red glowing face tachs to mount on the steering column. THEN I'll be fast!

 

I'm not absolutely sure about this, but I believe the tach and speed drives are magnetic based and the needle ain't attached to the cable so it can float around some. I wouldn't lose any sleep over what it reads at idle unless you spend way too much time just sitting still! LOL
Then again, you could always buy an Autometer 8,000 rpm, 5" Monster Tach with shiftlight like me! and quit worrying about the stock one altogether!