Car question - Rear Diff

va_rider

va_rider

Wizard
fz1boone.blogspot.com
So, I've got the chance to get an awesome deal on a complete rear-end for the SRT.... stock rear is 3.06 open diff. The one I'm looking at is the Getrag limited slip unit with 3.73's.... Currently, I can cruise at interstate speeds (70-75mph) at around 1800 RPM and I can average 22-24mpg... Would going to 3.73's on a car that I daily drive be insane?
 
You'll increase RPMs but have more applied torque to the ground. It's a matter of how much of what do you want... economy or performance? I'd go taller and take the performance. You can always swap back if it's too much, or drop to a 3.50. Based on the ratio, I'm estimating 2250 RPMs at 75 mph with the 3.73. With that engine, I'd want to take advantage of putting more of that power to the ground. Go for it!
 
Last edited:
3.02 to 3.73 isn't too much of a difference. You're looking at about 2200-2300 at 70-75MPH. The link below is handy for a quick rough calculation to determine RPM. Going from an open to Getrag LSD is totally worth it in my book. FZ1inNH hit the nail on the head as to why. As far as millage, you MIGHT lose 1-2 mpg. My old Supra was turning 2800 at 80 with 3.73s at I averaged 28-30mpg as long as I stayed out of heavy boost. Good luck and have fun with the install.

Tire Size, RPM, Speed, and Differential Ratio Calculator
 
You must log in or register to reply here.
Back
Top