Drivetrain Gears, Speed, Rpms.

Discussion in '2010 - 2014 Specific Tech' started by Al Fair, Dec 6, 2013.

  1. Hi guys. New to this forum but I'm gonna ask a common question. I've had seven mustangs since I've been driving. And I've upgraded all of them to a certain point with bolt on parts and as many power and torque adders as I could. The most common change I've always made during the first part was gear changes with different results. Currently I own a 2010 GT. Just a JLT CIA Hurst shifter flowmasters and I recently added 4.10's. I'm in the process of getting eventually a programmer. I'm not used to just how much the cars computer is affected by performance changes so here's my question. Without a program to adjust the speedo, how much is the speedo usually off with 4.10's in the 2010 GT? Also what rpm would the car be pulling at 65 mph. I have a set of aftermarket wheels 18 inch . I'm thinking they ar 18 by nine front 18 by 9 1/2 or 10 out back. I bought it used so not sure. I def know they are18inch. Any help is greatly appreciated. Glad to be back in a pony its been a while!
  2. Don't know the answer BUT if you have a gps you could just compare that to the speedo and figure it out. My tomtom is dead on for mph.
  3. He's right my Garmin shows the difference due to my smaller tires. I went from 17x7 to 18x9 but the tire is shorter. tn_Razor rims 001.JPG
  4. Thanks. Ill def give it a try.