I personally would just build a 9inch they are so cheap. You could buy a housing, TA mount, and 31 spline axles from moser for $900. Then i would just to a salvage yard and buy a 31 spline posi center section out of a ford pick up with the gear ratio of your choice. Some guy was selling the center sections on ebay for $150 for a 31 spline 3.50 9 inch posi. So for about $1200 you have a damn strong rear that would be tough to break. JMHO. If i could do it over again thats what i would do.

 

The original post clearly asks about the relative merits of all three configurations.

 

I am running alot more than 500 rwhp I run BFG Gforce on the 10 bolt with soft gears, hard axles and a eaton posi. So far so good? Im not saying it wont break tomarrow but I beat on it pretty hard. But out of the whole It will smoke the tires before I hurt the rearend.

 

i hear you chicken,my orginal ? was ref a 9 inch or a 12 bolt,but later i nquired if building the gm 9 bolt worth it

 

no sweat all is kool

 

The answer is ..........................

Strange 12 bolt

Lighter than all others - some may weigh 50 Lbs more
Lower loss than a 9"
You absolutely will not break it footbraking an automatic even with slicks
Torque arm bolts go thru entire arm and center casting - bolts tend to come loose on other styles.

Steve

 

I have a 9 inch just because I never wanted to worry about it EVER! It's also slick to be able to slip in a different gear whenever I want (highway gears vs. drag gears). As for the weight, an aluminum center section is available and is only 150 dollars more than the nodular case. Saves almost 30 lbs. Fit the package with a lightweight spool and lightened gears and the losses aren't a major concern.

 

I can only tell you my experience. I've broken several 7.5" 10 bolts in a few 4th gen F-cars. For our 95 we put in a Moser 12 bolt with 33 spline axles and a posi unit. I have had no problems and have fed it 700+ ft/lbs of torque at the rear wheels and made several 10.4x passes. It seems to be holding up fine. If you're going to the trouble to build that motor you owe it to yourself to build the rest of the driveline to take it. You won't notice a 3% power loss if you never knew you had it but you will notice broken gears, axles, etc...

 

12 bolts are NOT bulletproof! Why do I say? Cause my Moser broke the posi and bent the pinion on my first track pass and i'm not even pushing 500hp. About 400 at the wheels and that pass was a 1.64 60ft with a 3000rpm launch on ET streets and it's a 6spd. And I got nothing but hell from Moser trying to get a new ring and pinion after they sent a new posi. Very unhappy with them. If I were you, go with a 9". By design, I think they have much better pinion support then a 12bolt. Don't use a spool if your ever gonna drive it on the street. If you do go 12bolt, go with Strange and definitly go with a solid pinion spacer. Even if they can't build you one, take the rear apart and put one in before you run it.

Ken R.