9'' vs. 12bolt whats lighter
11-07-2007, 08:22 PM
#1
9'' vs. 12bolt whats lighter Im starting to research on rears for my car now. I want to really keep the weight down on my car so im trying to figure this out.
All aluminum 9'' center (aluminum center, aluminum yoke, lightened gears/spool etc.) in a fab9 housing
vs.
Bolt-in 12 bolt from lets say Moser.
My main goal is to keep it as light as poss. and rotational mass to a minimum. I know im gonna be scraficing strength but im not worried about that for a long time now seeing my car will make 450ish hp. And i know this is gonna be way over kill but im doing it right the first time around
All aluminum 9'' center (aluminum center, aluminum yoke, lightened gears/spool etc.) in a fab9 housing
vs.
Bolt-in 12 bolt from lets say Moser.
My main goal is to keep it as light as poss. and rotational mass to a minimum. I know im gonna be scraficing strength but im not worried about that for a long time now seeing my car will make 450ish hp. And i know this is gonna be way over kill but im doing it right the first time around
11-07-2007, 09:36 PM
#3
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the physical weight of the complete assembly or the internal "weight"of resistance?
a 12 bolt turns easier than a 9inch, 9in with an aluminum chunk will physically weigh less.
a 12 bolt turns easier than a 9inch, 9in with an aluminum chunk will physically weigh less.
11-08-2007, 01:14 AM
#6
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The pinion gear placement is more efficient in the 12 bolt, it takes less actual power to turn a 12 bolt than a 9". They also make 9" housings and 12 bolt center sections, burkhart housing and 12 bolt center section? Would be light and more efficient =)
11-08-2007, 01:55 AM
#7
well i planed on buying a midwest chassis fab9 housing and building a light center for it. Or my buddy has a moser12 that he would sell me but id end up spending $500 more for it then if i did the fab9. So im weighing out my options here.. (no pun intended, lol)
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11-08-2007, 06:07 AM
#8
FWIW, my dana60 from strange with a spool and 3.73's weighed 185lbs. It had the upgraded chromoly 35 spline axles, the upgraded cover (logo'd aluminum) and bigger wheel studs. It was right around 2G's. The spool saves a TON of weight. The spool sucks less power than a posi, is stronger, and the dana geometry is the most efficient. The stock 10-bolt weighs around 160-165ish. So, mine weighs 20 more lbsthan stock, can handle over 1000hp, and sucks the LEAST amount of power of the big 3 (9", 12 bolt, dana). Easy choice for me.
11-08-2007, 08:26 AM
#9
I am in the same boat Jerry. From what I have gathered is, if you get a Fab 9" with all of the lightweight options, shaved gear, lightweight spool, gun drilled axles, etc; it should be less drag than a boltin 12 bolt, but cost about $1,000 more.
11-08-2007, 09:31 AM
#10
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Ive broken my 12-bolt 5 times 4 sets of gears and 2 posi's. I'm almost surely going with a Dana 60 over the winter. Talking to Strange, they told me that the weight of a Dana with a spool and 35spline axles is 17lbs heavier then my 12-bolt is right not. 17lbs is not much.
11-08-2007, 11:23 AM
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I like the look of the new S60, 9 3/4 gear and is more efficient but some of the people talking about the torque arm provision not being tested kinda scares me, because I am going to beat the crap out of my next rear end and need it to handle the power and clutch launches.
11-08-2007, 07:53 PM
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11-08-2007, 08:01 PM
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My local shop ordered 6 dana's. 3 of them posi, 3 spooled. The spooled ones all weighed around 180-185ish. The posi ones were all over 235. The 235 was with the e-brake on them.
11-09-2007, 09:07 AM
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I sold the 12 bolt. The spool is a lot lighter than any posi. Why weld the gears and carry the extra weight? Just get a spool and be done.
11-09-2007, 06:10 PM
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My billingsley Fab 9in shipping wieght was 175lbs and that was fully loaded with brakes and everything. 40spline spool, gundrilled axles, light center section, strange brakes, swaybar, wheelie bar mounts.
11-09-2007, 11:27 PM
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The difference between a spool and posi is NOT 50 pounds, who ever gave you those numbers is full of it.