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Hey Guys,

I'm brand new to the forum. Just picked up my 70 Malibu today and started tearing the front clip off. I have found a lot of great info on this site.

Should I trash my 10 bolt and go with a 12 bolt or a 9 inch? It seems like some guys think the 10 bolt is strong enough with modifications.

I am planning on a big block with close to 500 hp with and auto trans.

Thanks
 

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Get a 12 bolt! I just tore up my new 3.36 gears with my 8.75 10 bolt! I did a small burnout and the next thing I heard was my rear gears grinding. There was a 1/4 inch dent in the rear cover where a part of a gear shot out at it. 12 bolts are a lot tougher and can handle more torque. Trust me, I learned the hard way!
 

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Note that the 10 bolt was available in two ring gear sizes: 8.2" through the early '70's and 8.5" from the early '70's on. I have successfully used an 8.2" 10 bolt with more power than you are talking about - but I wouldn't do it with slicks. The 12 bolt (which has an 8-7/8" ring gear) vs. a 9": at your power level you do not need a 9", and you will benefit from the efficiency of a 12 bolt - the 9" is ~ 1% to 2 % less efficient in transmitting power.

You can break any differential - I saw a Chevelle blow up a 9" differential the last time I was at the drags. On the other hand I have a couple of friends racing with 7.5" differentials, running solid 12.5x e.t.'s and using slicks in 3,700 lb drag weight cars (late model F-body). I keep on telling them that they have the "miracle" 7.5" differentials. The main thing is to have the posi set up tight, if loose they tear up the posi clutches and send debris through the gears and bearings - then BANG, its over.

Thomas
 

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I'm thinking about a Strange S-60 too. I'm running a 500+ ft.lb. 454 thru a Super T-10 in my '66 Elco.

How are these in terms of transmitting power efficiently? Do they cost power like a 9-inch compared to a 12-bolt does?

Just what ever was so good about a Dana 60 compared to a 12-bolt anyway?
I mean, if you aren't running a Mopar, why go to the trouble to convert, back in the days before you could just get a bolt-in from Strange?
 

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The Dana 60 has a 9 3/4 inch ring gear! That is almost a full inch larger than the 12 bolt. It also has 35 spline axles, compared to 30 in the 12 bolt. All of this extra strength comes at the cost of extra weight. They don't require as much power as the 9 inch, but more than the 12 bolt, just because of the extra rotating mass.
 

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Dave, the deal with slicks is that upon the instant of launch a sticky tire lets the differential (and everything really) see more of a shock that twists axles etc. On the other hand a non-sticky street tire dissapates energy through spinning the tire, so the axles see less twisting etc.

The Dana 60 is overkill for just about everything, but it also will have a long life in a drag car. Get gun drilled axles for a Dana 60, along with a cut back gearset and the weight penalty disappears.

Thomas
 

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Once you get used to 500hp, you'll want more. Spray that one, then it won't be enough so you'll stroke it. Believe me, the hp bug bites hard when he gets ahold. One of my guru's favorite expressions is, "Build it as big as you can - you'll end up there anyway, why spend the money twice or 3 times?". Go ahead and pick up the 9" so you don't have to buy it later. You can get a housing with mounts already welded to the right spots for $325 delivered from a guy on ebay. Add some Strange or Moser axles an "N" center section and you'll be ready to go. The 9" gives you the option of changing center sections fairly quickly so you could run a 1/4 mile track one night and 1/8 the next without having to completely redo a rear end.
 

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I agree with the last post.... Go with the 9in... easy to get parts.. and you will end up needing it anyway. Currie makes a great setup that will bolt right into your car. I'd give them a call. I have a Currie 9in in my 65 Chevelle and it was one of the best investments I have made.

Steve
 
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