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

 

My Fab 9 from Burkhart is a lot lighter thn the Moser 12 bolt it is replacing.I didn't weigh them but I would say a good 20+ lbs.

 

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.

 

12 bolt takes less power to run than a 9" will.

 

hummmm... all interesting. If everything is lightened in the 9'', what makes it use more power?

Steve.. wanna sell me the 12 bolt??

 

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 =)

 

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)

 

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.

 

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.

 

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.

 

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.

 

my 10bolt was 150#
s60 was 196# FYI

same parts/ fuild on them.

 

anyone know what a 12 bolt with a lightened spool weighs? Or how much lighter a spool is from a locker?

 

A strange 33 spline light weight steel spool weighs 8.85 lbs, can't find the weight of a detroit locker, but it weighs more.

 

a spool s60 shipping weight is 40#s less then a ture trac s60

 

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.

 

what about instead of getting a spool, u weld the gears, I had welded gerd on my 85 Monte SS that was my daily driver and never broke.

 

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.

 

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.

 

The difference between a spool and posi is NOT 50 pounds, who ever gave you those numbers is full of it.