Maybe I should rephrase the question:

What are the advantages and disadvantages of the 9-inch rear versus a 12-bolt rear?

I'll assume two likewise configured aftermarket designs by Moser: As an example, two F-body axle assemblies, with limited slip differential assemblies, and rear disc brake options, and no ABS ring to worry about. For the sake of argument, an axle ratio of 3.42 to 3.73:1, set up for torque arm, coil springs, and lower control arms.

Something capable of handling a low-10 second E.T and a 1.3 second 60-foot launch from a 6-speed.

Is there a weight advantage to one versus the other? It there a strength advantage? Does one have a better pinion angle than the other? Does one design more efficient at transferring torque than the other?

I'm in the dark, and need to find education. My car is mostly configured for open lapping days on a road race track.

--Dan

 

the 9" is just a plain design. if you are hard up for all gm parts then the 12 bolt is for you. All i have to say is monster sized ring gear and a non-overhung pinion gear.

 

Well the 9" is stronger,heavier and has about 2-3% more drivetrain loss then the 12bolt.If you go 12 bolt get a spool and not a posi if you plan to run that fast.A few people have been blowing up there posi units in there 12 bolts.