12 bolt vs Dana 60
 

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.

Re: 12 bolt vs Dana 60
 

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

Re: 12 bolt vs Dana 60
 

I wouldn't carry a Dana 60 , unless it was for the 6.50 ratio.
Come to think of it, there's your real answer ;-)

Re: 12 bolt vs Dana 60
 

...or a 7.17 ratio... :D

Re: 12 bolt vs Dana 60
 

with the ratios of 5.86 - 6.14 the 12 bolt pinion is very small. It may have been an isolated case but with the 5.86 in my Super 10 it did not hold up. Even with a Cryo treated gear set. Installing a 5.57 gear gained one more tooth on the pinion and gear life was much better. This was with a SS 327 running 10.30s at 8400 - 8600 RPM at around 3250 pounds

Re: 12 bolt vs Dana 60
 

Isn't the 12 bolt about the only rear end that is more efficient than a Dana 60?

Re: 12 bolt vs Dana 60
 

Jeff, was that weight difference with a limited slip diff, or a spool? Over 20 ears ago, when I switched my bracket car from an automatic to a Jerico 4 speed, I decided the old rearend needed updating. I had been using a Ford 9" with 33 spline Strange spool and axles, with a production Ford Nodular iron case, and an unbraced early style housing. After some research, I came to the conclusion that bracing the existing housing, buying an aftermarket case and bigger axles and spool would be comparable to scratch building a Dana 60. So I sold the old 9", and my buddy built a new Dana 60, using a thick tube (heavy) truck housing, billet caps, 35 spline spool & axles, and a T/A load bolt cover. Having heard all the stories about how heavy a Dana 60 was, I was pleasantly suprised when I weighed both rearends. Using the same model brakes, the Dana was a mere 6 pounds heavier than the 9". Now, keep in mind, the Dana had thicker, heavier axles, and was a thick tubed truck housing, while the 9" had a light, early housing and smaller 33 spline guts. I think the move to 35 spline axles in the 9", plus a braced housing would eliminate that 6 pounds. And if I bought an aftermarket iron case, be heavier. Now, I know an aluminum case would make the 9" that much lighter, but again, if I used a thin tube Dana housing, the Dana would also loose some weight. A Dana clutch style limited slip is a huge, heavy unit, replacing that with a spool drops a lot of weight. I can say, after 20+ years of 6000+ RPM clutch dumps, the Dana has been as reliable as an anvil. I have 3 sets of Pro gears of various ratios, and each set has at least 7 years on them, and they all still look great. Only strikes against a Dana that I see, is not as many ratios available as a Ford 9", but the 12 bolt is in a similar situation there as well. Plus the Dana is not as easy to change gears, as throwing another chunk in a 9", but again, same story with the 12 bolt. For my purpose the Dana is a great choice.

Re: 12 bolt vs Dana 60
 

8.8 Fords are like 12 bolts very efficient. I ran an 8.8 with 5.71's weighing 3100, trans brake,10.60's no problem.




Bret Velde
2003 ??/SA

Re: 12 bolt vs Dana 60
 

With a steel spool, 33 spline axles, aluminum cast cover with bolts to keep caps in place. Might get in trouble with thin tube housings. I did bend 1 12 bolt housing with no HP stick car that weighed 3775

Re: 12 bolt vs Dana 60
 

Mark, don't think I will need a 6:50 for this combination. If for some strange reason I do, I will try a shorter tire to add some gear.

Re: 12 bolt vs Dana 60
 

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.

Re: 12 bolt vs Dana 60
 

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.

Re: 12 bolt vs Dana 60
 

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.

Re: 12 bolt vs Dana 60
 

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.

Re: 12 bolt vs Dana 60
 

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?

Re: 12 bolt vs Dana 60
 

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

Re: 12 bolt vs Dana 60
 

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

Re: 12 bolt vs Dana 60
 

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.

Re: 12 bolt vs Dana 60
 

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

Re: 12 bolt vs Dana 60
 

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.

Re: 12 bolt vs Dana 60
 

My cousin has a '71 Chevelle it's a bracket car, weighs 2920 with a 555 CI,runs 550s in the eighth mile with a 12 bolt. He was only getting about a hundred runs out of a ring and pinion but switched to a 488 I believe has a larger pinion? It has a t a girdle on it and good axles and spool but it's nothing special.

Re: 12 bolt vs Dana 60
 

Hey Tom. Good to hear from you! Primary reason would be weight, if any performance it would be gravy. While I have no prob with the 14.00 break in GT class. I can't get light enough for the 13.50 break GT class. I had forgotten Rick had one in is hemi. I do need to call you soon and discuss something though.

Re: 12 bolt vs Dana 60
 

Since I have parts for both 12 bolt and Dana 60 in the shop right now ,I decided it was time to weigh in ,literally by putting everything on the scale.
Both rears measured within an inch of each other ,12 bolt 53" ,Dana 54" both have 1/4" chrome moly tubes and 3.15"bearing ends, both have steel caps.
Dana 60 90 pounds ,
12 bolt GM 70 pounds
Both have Strange light weight steel spools
Dana 60 13 pounds
12 bolt GM 8 pounds
Both have standard non lightened gears
Dana 60 16 1/2 pounds
12 bolt GM 14 pounds
Axles and bearings and yokes are within ounces
So the total unsprung weight difference is 27 1/2 pounds and rotating weight difference is 7 1/5 pounds.
The Dana still is better for frictional loss efficiency than the 12 bolt but that surely is offset by the difference in rotating mass.
Bottom line is both have their strengths and weaknesses . Ratio choice is much better for the 12 bolt for sure , and if we are talking a Stocker ,well you know what you
have to do .

Re: 12 bolt vs Dana 60
 

Question, what does a COPO, Cobra Jet and Drag Pack cars have for rear ends and what gear ratio and tire size? Thanks

Re: 12 bolt vs Dana 60
 

9 inch Fords in Chevy new Mopar and Fords

Re: 12 bolt vs Dana 60
 

What gear ratio and tire size on those different manufactures