I have seen this asked many times over the years on this forum.I figured I would ask this same question again because i have replaced these items and the speedo is still inaccurate.
The speedo is accurate up until about 40-45mph. By the time I get to 80mph, the speedo reads 55mph.

My car: 93 accord, well over 300k miles, 5speed stick.

I have never had any jump/bounce in any of my gauges.
All of my gauges including the tach have always worked. I drive via tach and 5th gear for accurate mph.

I replaced the VSS with a used one from my parts car. It didn't fix the issue.
I replaced the VSS with a new Ebay VSS. It didn't fix the issue.

I replaced the spedo (not the whole dash cluster) with a used speedo from my parts car with 200k miles on it. It didn't fix the issue.


I don't expect a solution... But I figured that I would ask just in case someone had a solution.