how much of a difference will swapping the 3.23 ring and pinion in my 87 iroc to a 3.42 make in my 0-60 and1/4 mile times and what do i do to re calibrate the speedometer

 

well, when I went from 3.08's to 3.42's, it was a night/day difference, what an improvement it made in my acceleration. I also did some other stuff at the same time, so I cant really tell you how much of an improvement it made. You will definately see an improvement going from the .23's to the .42's but it wont be as much as it was for me. to recalibrate the speedo, you have to get the correct speedo drive gears for those gears, one thing I havent done yet. but I just calculated the difference the gears would make in the speedo and noted what the new speeds are. not too hard, but sometimes I forget and wonder why people are flying by me on the highway when Im going 65.