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