12 Bolt or 9in.?

[Ryan02z]

Is there a benefit between one or the other? Both seems pretty bulletproof? The 12 bolt seems like it's more versitile compared to the 9 inch is like a solid rock. What's the weight differences on these btw?

[youngrigo aka NVEEOUS]

I dont know the weight difference, but some say the rule of thumb is 9in/m6 12 bolt for an auto.

[1BadF-body]

Iam gonna go with a 12 bolt when I save up enought money with 373 gears..

[PNISSHR]

Im gonna bring back this from the dead. I would like some opinions on this as well, maybe even a fact or two.

[firebirdmuscle]

Originally Posted by PNISSHR

Im gonna bring back this from the dead. I would like some opinions on this as well, maybe even a fact or two.

yes as i'm in this situation too

[chevymec]

Originally Posted by youngrigo aka NVEEOUS

I dont know the weight difference, but some say the rule of thumb is 9in/m6 12 bolt for an auto.

x2 I agree.

[PNISSHR]

Originally Posted by youngrigo aka NVEEOUS

I dont know the weight difference, but some say the rule of thumb is 9in/m6 12 bolt for an auto.

What is the reason for this? Is it because the 9in can handle a bit more abuse?

[Wooshie]

Strength of the unit is this:

Strongest to weakest:
Dana60, 9-inch, 12-bolt (with the 12-bolt being much further back). This will not be an issue with 99% of the people out there. 12-bolts are VERY strong compared to our stock rears but if you plan on single digit track times, I would look elsewhere.

Price:
They are all about the same. Expect to pay around $2400ish for a posi rear, and $2000 for a spooled rear irregardless of which unit.

Spool or no spool?
If your car is a dedicated track car, that enjoys the occasional cruise here and there, AND YOU KNOW FOR A FACT THAT YOU WON'T GET CAUGHT IN THE RAIN, then by all means get a spool. The weight savings alone is about 40lbs over a posi-equipped rear. It is stronger too.

Perks about each unit:
12-bolt, it keeps your car 100% GM, it is pretty popular, it sucks marginally more hp than your 10-bolt, it is the lightest of the 3.
Dana60, it is the strongest, comes with 35 spline axles standard, has the best pinion placement for hp loss, although the shear size of it makes it suck more hp than the 10-bolt.
9-inch, VERY POPULAR, can buy different center sections with different gear sets and swap gears in no time. Tons of options available for it with regards to axles, gear sets, etc..

Drawbacks to them:
12-bolt is the weakest. Some hard core guys can break them. There are options to make them stronger but they add to the price ie:bigger axles. Can use stock driveshaft.

Dana60. It's heavy. Expect a posi S60 to weigh between 220-230lbs, a spooled one will only weigh 185. You will need a new driveshaft.

9-inch, It's heavy as well. It "supposedly" sucks the most hp to turn it because of how low on the ring gear the pinion gear engages. You will need a new driveshaft.

All 3 will suck more power than your stock 10-bolt, meaning if you ran 12.50's before, expect to run 12.60's or worse when you swap rears. All 3 will add considerable value to your car as well. All 3 are light years stronger than the stock 10-bolt.

[PNISSHR]

good info, thanks!

[firebirdmuscle]

sweet.

[DoggyB22]

good info... Don't you wish there was something out there that didn't have a drawback. But id still go with a 9". Just prepare to hear it from the "Ford owners"

[firebirdmuscle]

Originally Posted by DoggyB22

good info... Don't you wish there was something out there that didn't have a drawback. But id still go with a 9". Just prepare to hear it from the "Ford owners"

haha, what they dont know what hurt em. unless they just gone lay down and look up under my rear.