12 bolt vs Dana 60

[Mike Pearson]

Originally Posted by Ed McLawhorn Jr.

Been thinking about taking very heavy dana out and replacing with 12 bolt. Its known the Dana is bullet proof and takes more energy to rotate than 12 bolt. Car is a 283 ss/gt auto in 3430lb wagon with a 6:20 gear and 30" radial tire. There was a 12 bolt with 6:14 and 28.5" bias tire dad ran in the car in the 80's before rules changed on heads. Besides more hp to run dana, I'm looking at the difference in weight. With dana, I'm pretty much locked into one gt class due to not getting light enough. Would the oem 12 bolt hold up or do I need to think more about an aftermarket housing and is a good 6:14 still available? Thanks.

With good parts you should be able to get a couple of seasons on.a R&P. One of my friends ran a 12 bolt in his GT car. 350 295/313 combo at 3100 and would get 2 seasons on a 5.96.

[GTX JOHN]

We have replaced most of our 8 3/4 mopar rears with Dana 60 AND lost no ET whatsoever on our Stock and SS stuff.

[Ed McLawhorn Jr.]

Originally Posted by Jeff Stout

12 bolt with aftermarket goods will hold up. I'm 3360 10 flat ET with trans brake and around 170 passes. No noise yet. Did break a 4.56 street gear. Went pro gear and that's been it. Also used 4.10 gear with 9 tooth pinion and no problem. If I remember I think 85 lbs lighter then dana

Jeff, the only difference in car now and when dad ran it is the truck Dana with thick tubes and a coilover shock replacement. Car with no driver is right at 95lbs heavier now. I found some old weight numbers, so your 85 lbs might be close.

[Ed McLawhorn Jr.]

Originally Posted by GTX JOHN

We have replaced most of our 8 3/4 mopar rears with Dana 60 AND lost no ET whatsoever on our Stock and SS stuff.

John, my main reason for exploring changing to 12-bolt would be the weight difference. Any performance would be gravy. Where I'm at now, I'm stuck with one class and have little to no flexibility to move up a class unless I want to run over 90lbs heavy. There's 116lbs difference to move up one class.

[Myron Piatek]

It's been a few years since I switched from a braced 8 3/4" to a Dana 60, partially to gain some weight and was confident of no ET loss. I think it was only about 30-40lbs difference. Haven't run the car much, though.

Dana 60 is more efficient than an 8 3/4, but not more than a 12 bolt. (I recall an magazine article from the '70's or 80's. Not much, but it's there.) When bigger parts are cut down, like shaving weight from a ring & pinion, spools, etc. the differences in weight will be reduced. A 12 bolt will help in weight & efficiency over a Dana 60, but I have no idea about the actual weight comparison and it may sacrifice a bit too much durability. Seems like the ring & pinion is the weak link in an 8 3/4 as well as the 12 bolt.

Lightened ring rear, drilled axles w/milled flanges, Kirkey seats, aftermarket brakes?

its a couple of dollars, but an aluminum spool, gun drilled lightweight axles, and if you dare ceramic bearings i think the Dana will be just as fast as the 12 bolt and not have the gear trouble either, + 6.50 and a 7.17 option is nice as well. it will also last forever. you already have it in the car as well

[Myron Piatek]

If you're still wanting to try the 12 bolt, perhaps Charlie Boyles could offer some advice and what to expect with a 12 bolt.

http://www.competitionplus.com/drag-...a-legend-lives

[Dwight Southerland]

Hypoid angle for a Dana 60 is less than a 12 bolt. Several years ago, Car Craft did a side-by-side comparison of a 12-bolt, a Dana 60 and a 9-inch. The 9-inch was the loser. No clear winner between the 12-bolt and the Dana.

[Tom Meyer]

I have run a 12 bolt in my Chevy II forever, steel spool reg axles 6.14 gear. 283 SS car with brake 6000 + . Used good gear oil and had very few problems putting hundreds of runs on the gears. Only if I was looking for saving weight would I switch. There is a difference in sprung and unsprung weight that may pick the car up. Unless you get the 12 bolt stuff cheep money might be better on other go fast parts. Way back in the day Rick Johnson ran a 12 bolt in his hemi car. Tom

[Bench Racer]

Originally Posted by SSDiv6

...or a 7.17 ratio...

My Brother ran a Dana with 6:83 and a 2:75 low gear in IHRA Production with a 283c.i. 1958 wagon . The car was a tank at #3839 and low gear was a short ride lol, he shifted at 10,500 rpm. Never broke a gear in the Dana.