How to determine rear axle ratio in a back half car??

[bignastygs]

I am biting the bullet and selling my brand new rear end that I had built for my 70 Buick Skylark. I am now in the midst of getting a S&W A body ladder bar back half kit and will be installing my 15x14 Buick ralley wheels on the car. It is suggested a 31x18.5x15 slick can be used but I have 14 inch wide rims and the tire suggested is 14.5. Should I get the 14.5's? I am also going to a Ford 9 inch rear with rear disc setup (stock pieces) I am running a TH 400 trans with reverse pattern manual valve body. My motor will be built to operate in the 6000 rpm range and I need to determine rear gear ratio. Any suggestions to what I should shoot for??

[fishmanjoe]

HEY BIG,On the site,www.hardcore50.com,they have some math formulas for working out rear end ratios and such.Maybe it might help you.FISHMANJOE

[zipper06]

here you go.

Zip.

http://www.wallaceracing.com/Calculators.htm

[bignastygs]

Thanks for the links guys..It was really helpful. By doing some initial calculations as well as asking a friend who has a similar build to what I want,Looks like in the 4.30 range is where I need to be.

[signsbyesa]

4:56 works well with that size of tire, good luck :wink:

[twobad1]

4.56;is what i ended with w/32in.tall tire 4.10 was at 5500 at traps
56 was 6100 good luck!