Speedo gear and different rear end

[dmvu]

Hello everyone, heres the issue im trying to figure. I have a 1986 ttype and when I purchased the car, it had another rear end in it. From what i know, its a 7.5 read end, open diff and appears to be 2.41 gear ratio. Given that information, the speedometer reads too slow, i put a gps in car to track actual speed. The speedometer would show 45 for example and actual speed would be about 66. I am looking into changing the speedo gear. Based off the speedo gear calculator, i input 26 inch tires and 2.41 gear ratio. Shows 0.53 ratio and need a 20.5 teeth gear. I dont think they even make 20 or 21 teeth gears. This is where im currently at and want to have correct or at least very close to correct speed. Any suggestions? Thank you

 

[grass doctor]

you will need to know what gear is on the governor in the trans as well... you will want the stock orange gear on governor in trans with your stock wheel height and very close stock rear end ...I can't rember the speedo gear off the top of my head ..but should be pretty easy to look up ..

 

[grass doctor]

here's a good thread...

https://turbobuick.com/threads/what-speedo-and-or-driven-gear.451103/

 

[dmvu]

you will need to know what gear is on the governor in the trans as well... you will want the stock orange gear on governor in trans with your stock wheel height and very close stock rear end ...I can't rember the speedo gear off the top of my head ..but should be pretty easy to look up ..

I checked and it’s the 11tooth orange governor gear. The issue is the car doesn’t have the original rear end anymore, its a 7.5 open diff with 2.41 gear ratio. I need a 20-21 tooth speedo gear but it isn’t offered. 26 tooth appears to be the lowest.

 

[grass doctor]

if you have the 11 tooth orange gov gear ...you will want a blue 30 tooth speedometer drive gear....if your rear end gear ratio is 3.42 with 26" tall tires...