Ok Math wiz!

[vader87]

Found a place on line that sells gear reduction or speedup box for our speedometers. I am a little slow when it comes to math so here it is:

Running the 200 tansmission with 28 inch tire and 3.42 gears.

While traveling 74 MPH, my speedo reads 60. A 20% speedup will get me close to where I need to be. I have a 145 mph overlay that I would like to install so what percentage slow down or speed up box will I need?

Here is the link:
Speedometer Gears, Speedometer Gear, Ford, GM, Dodge 700R4

 

[87we410877]

18.9 % speed up will get your 85 mph spedo reading correctly. Whatever the reduction is for the 145 mph spedo on top of that is what you need. I think the reduction is 58% for teh 145 spedo so your total would be 58 - 18.9 = 39%. Someone want to double check this? I have no experience in the spedo thing but am pretty ok with numbers. HTH.

 

[vader87]

Cool so anybody know?

 

[BlackBandit]

I came up with 39.7 reduction from current.

 

[mikestertwo]

I posted the answer in the tranmission section where you posted first.