there is some math to do in regards to the rear end. Multiply the rear end gear by the first gear. You want to be over 9 and under 10 IDEALLY.
example:
Rear end: 3:23 ratio TIMES First gear on tranny 2.85
EQUALS
9.21
That gets you off the line correctly.
If you have 2.90 gears or something in the rear end and put a M-22 (2.52 first gear)in, you will not be happy getting off the line as the math comes out to 7.31. A so-called "close ratio M-22 would have an even higher first gear at 2.20, so that would be very bad off the line...This is why you would see that transmission with a 4:11 rear end oftentimes, where you get the total gear value at 9.04.
You want to be over a "nine" so just do your math, when going with a 4 speed
If it is too high, you will be gear bound. So do some homework upon switching it up, and change the gears somewhere, either in the tranny or in the rear end if need be.
Good luck.
I like math and nice, tidy equations like this(above). I'm going to put this math to the test in the spring. I recently bought an unfinished project car that will do it. It has all new drive train components. The engine is an aluminum head Pontiac mill that is built close to RA IV specs. The trans is a 2.20 M-21. The rear gears are 3:23. (2.20 x 3.23 = 7.106) With the above mentioned equation, I should have very little power off the line. Since the builder of this car had a lot of experience, I'm thinking it will be just fine for cruising. We will see when the rubber hits the road.....
