12 bolt vs Dana 60

[ImBack]

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.

[Ed McLawhorn Jr.]

Originally Posted by Mark Yacavone

I wouldn't carry a Dana 60 , unless it was for the 6.50 ratio.

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.

[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 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?

[Rory McNeil]

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, 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.

[Jeff Stout]

Originally Posted by Rory McNeil

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.

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

[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.