another speedo thread... but mines weird

[BigHairyMonkey]

The cars supposed to have 3.73's, and on the freeway i spin about 2200 @ 65mph. Then i find out that my speedo is reading 10 mph SLOW... wtf?! i was goin around 59 and my friend says that hes close to 70, what gives? I also had this confirmed with another friend (i always wondered why everyone was always goin like 55 on the freeway, but then i realized its just cause we're actually goin around 65 ) My tires are 245-50-16s

 

[TENGRAM]

what speedo gear are you using? what year stang is the transmission out of? either way a 23 tooth speedo gear will get you about as close as you're gonna get. should put you within a couple of mph of accurate

 

[BigHairyMonkey]

i thought gears would lead me to read fast not slow

 

[BigHairyMonkey]

anybody?

 

[ninety15.0]

Given that you were turning 2200rpm at 59 mph means that you actually have either 3.90's or 4.10's. With 3.73's i run 60 mph at 2000 rpm. Like everyone said...put the white 23 tooth speedo gear in there and see what happens...mine is fairly accurate with that gear.