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

Old 02-12-2009, 04:07 PM
  #1  
bignastygs
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Default How to determine rear axle ratio in a back half car??

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??
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Old 02-13-2009, 08:44 AM
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fishmanjoe
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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
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Old 02-13-2009, 11:50 AM
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zipper06
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here you go.

Zip.

http://www.wallaceracing.com/Calculators.htm
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Old 02-14-2009, 01:38 PM
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bignastygs
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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.
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Old 02-14-2009, 01:44 PM
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signsbyesa
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4:56 works well with that size of tire, good luck :wink:
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Old 02-16-2009, 06:21 AM
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twobad1
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4.56;is what i ended with w/32in.tall tire 4.10 was at 5500 at traps
56 was 6100 good luck!
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