Vader

95 Mustang GT Aode. 3.27's to 4.10's.


How much is my Speedo off now?

sastangman

i know for mine with 4.10's it is off 15 mph high standard t-5

luckythirteen13

id think there would be more of a discrepency then just 15mph. the faster you go the further off it should be. any reason you didnt put in a speedo gear? about $20 and 30min or less work

Chris C

There is an easy math way to figure it out but I have been out of school for 10 years so someone else with have to tell me which way is right. 4.10s are a % lower than 3.27s. That % is also how much your speedo is off at any given speed. So the faster you go the more off it will be.

4.10/3.27 = 1.25 or about 25% off

My math might be off but someone still in highschool can figure it out im sure. If you changed your tire size that will also change your speedo some.

Pure5.0

Chris is right. It will be 25% off. If you want to be exact it will be 25.38% off.

So just take your current speed and minus ~25% off.

So.....
Your speedo reads = you really are going
10mph = 7.5mph
20mph = 15mph
30mph = 22.5mph


and so on.........

90GTRagtop

Multiply your speedometer reading by 0.79756 to get your actual speed (assuming the speedometer was right with the 3.27's). That is if the speedo is reading 30, you're doing 23.9. If the speedo is reading 70, you're doing 55.8. 90 is 71.8 and so forth.

Vader

Thanks guys, I am pretty new to the mod world and I actually did not realize the speedo would be that far off. I will do a search on how to correct this.


Unless one of you wants to step me through it.

Chris C

90GTrag you divided 3.27 by 4.1 to come up with the .79756. So thats about 20% lower. Like I said its was either 3.27/4.10 or 4.10/3.27. Which way do you divide? the bigger # by the smaller or the smaller by the bigger to get the % off. I was good a math at one point in my life. Either way its 20% off or 25% off. Pure5.0 thinks its 25 also. So two votes to one LOL. Someone knows for sure.

Chris C

A speedo gear will correct it. You need one thats either 20% more teeth or 25% more

Magiarn71

You multiply by .79756

You cant divide the other way, get 1.25 and just drop the 1 to get .25

If you were going from 4.10 to 3.27, you would multiply by 1.25 to get the new HIGHER speed.