Since I decided to build a motorcycle, my motor swap plans won't happen for another year or so. I still have the 305TPI and 700r4 and am looking into getting 4th gen rear end. I can't seem to find one with 3.42 but the 3.23 rears are everywhere. I currently have 3.27 gears in the car and like it but would I benefit more from a 3.42 ratio rear end? I'm not sure if it is worth holding out for a 3.42 when I found a complete 3.23 an hour away from me for $200. I know I shouldn't go too low with the gears or the car will rev through it's powerband too quick so what does everyone think?

The car is my daily (summer) driver until I get the bike built. It will see the drag strip once in a blue moon, I do a ton of autocross, and I hope to start doing HPDE events this year.

 

you wont be able to tell much difference at all b/t the two. So if those are your only options, then go 3.23

I started with 3.42. Then bought a 4th gen rear with 3.23, swapped in some 3.73s and it still felt like the old 3.42s did.

 

why are you even considering swapping the 3.27 out for a 3.23? maybe a 3.42 you probably want even be able to tell the difference. 9 bolt is slightly stronger than the 10 bolt. i would stay with what you have right now unless there is something wrong with the rear.

 

The rear isn't worth keeping and I would rather run the wider rear then use an extra pair of spacers. My motor and any future builds won't make enough power to break the rear end. I'm also making the swap for the bigger LS1 brakes.

So, 3.42 won't make any difference? Do you know of a shift point chart comparing them or something. I'm not trying to sound like a smart ***, I'm just curious.

 

http://www.corral.net/tech/gearcalc.html

For example, in Drive, doing 55 mph, with a 245/40/R17, with the 3.42s you will be turning 2560. With the 3.23 it will be 2415.

Play around with it if you want. You will not feel a difference.