Differential calc - ZR-1 Net Registry Forums

XfireZ51 · 01-21-2012

OK guys. I'd like you to check my math. I am considering changing rear gearing due to the fact that my Z06 wheels are about 1" taller than stock and that my current speedo gear appears to have been there due to the car previously having 4.10s. It now has 3.45s. Using GPS, I find that the speedo to actual error is 10mph at 64 indicated/74 actual. This tells me that my error is ~15.6% tires and everything included. So it seems that the 3.45s are performing actually as 2.91s. If I want to get the performance of 3.45s, I calculate that:

If 3.45 = X*.844 (or 1-.156), then X = 3.45/.844 = 4.0876

Therefore, I need 4.10s

in order for the speedo to be correct and for the acceleration to be what it would be with stock gears.

Guess what I'm looking for now?

01-21-2012	#1
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,709	Differential calc OK guys. I'd like you to check my math. I am considering changing rear gearing due to the fact that my Z06 wheels are about 1" taller than stock and that my current speedo gear appears to have been there due to the car previously having 4.10s. It now has 3.45s. Using GPS, I find that the speedo to actual error is 10mph at 64 indicated/74 actual. This tells me that my error is ~15.6% tires and everything included. So it seems that the 3.45s are performing actually as 2.91s. If I want to get the performance of 3.45s, I calculate that: If 3.45 = X*.844 (or 1-.156), then X = 3.45/.844 = 4.0876 Therefore, I need 4.10s in order for the speedo to be correct and for the acceleration to be what it would be with stock gears. Guess what I'm looking for now?