ok in my 84 z28 it has the double sided speedo for mph/kmph:





if i took off the needle on the kmph side and made a custom face that all the numbers on the mph side were exactly the same as stock but on the new one instead of it changing over to kmph, make it so the lines and digits keep on going in mph so i would have like a 160 mph speedo?

what the real question is, does the speedometer keep going faster and faster past 85 MPH? accurately?

 

I doubt it's accurate now where it's marked out. Funny thing though, my speedometer wraps around pretty far going 119 mph at the track

 

Removing part of the needle will throw it off balance and make it difficult to calibrate accurately; it will climb slower to the 12 o'clock position, and faster from there downward. Imagine lifting a sledgehammer at arms' length up and around....
You could possibly clip enough equally off both sides to allow the orange portion to clear the trip reset button.

 

If this was true, there would be a counterweight on the later single-needle speedometers. Since there isn't, it suggests that the moment of the needle is insignificant compared to the forces turning it.

 

it simply dosen't go any further after 85mph. it just stops.

 

Not if he removed the little stop near the top. I've had mine way past 85 mph.