Like the title says.. For some reason my speedo is ~4mph fast.. I know it doesn't matter, but it's bugged me since I bought the car. And If the needle is anywhere under 80, it bounces just a hair (assuming gravity plays a part in that). It's the little crap that gets to me.. Don't get me started on dash rattles!!

 

oh god. i hate when there are bumps on the highway. or even local. my car sounds like its going to fall apart. i wish i knew where to even start looking....

 

Do you have OEM sized wheels and tires?

 

Yes, mechanical speedos can be calibrated.
It's done by putting a small gearbox between the cable and the gauge, the gear ratio in the box brings the speedo into the correct reading.
I had it done to my 240Z several years ago.

 

I am running stock wheels and tires. I'm not even sure how the speedo could be off...?