Hitman's Pontiac Trans Am Forum
Trans Am Information => Trans Am Tech => DriveTrain => Topic started by: N2Ofreak69 on December 30, 2015, 10:57:16 PM
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I have an April 70 12 bolt from a Ta. COX code. It is perfect and gears are date coded 4/70 also. My dilemma is this... Put it behind my N20 fed 575 hp off the bottle 76 TA and cut up the date coded housing for c clip eliminators or put a 9 inch in it and sell the 12 bolt.. I just don't want to ruin a perfect RARE piece..
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A 12 bolt can be assembled very well. You can probably just put the money into that thing and be just fine. The strongest in either rear will be putting in a spool. The ring gear diameter on a 12 bolt is 8.875" so the difference in gear size is 0.125" if comparing to a Ford 9".
Many also disregard gear ratio when considering the strength of any gear set. 4.56 is weaker than a 3.23 rear end gear because you have less contact on the larger set. This analysis is applied more to transmissions and disregarded when talking about rear ends. Torque capacity on any transmission is inherently weaker the further you get higher from 1:1 direct gearing. For example, a TKO (popular 5 speed swap) trans with a 3.27 1st gear is rated for less torque than, lets say, a 2.88 1st because of the contact pattern associated with gearing ratio.
Hopefully this puts some things in perspective.