Originally Posted by matts37chev
i would be interested in the actual amount of power that is "sapped" and what part of the 9" is doing the "sapping" i'm assuming its the extra pinion support bearing.
unsprung weight is a huge performance factor.
9" ford eats more power because of its low pinion placement, the pinion makes a heavier wiping motion on the ring teeth, more friction and less efficient power transfer than having the pinion enter the case closer to centerline.
I don't like the 9" because it costs so much to beef up for any serious performance work. Housing so flimsy it needs bracing, needs a nodular iron centersection(stock is cast grey iron), Daytona pinion support all add up to a lot more cost compared to a Dana 60 or 12-bolt.
I take a Dana 60 full-floater from a truck($100 at a local yard), gut it, chop off the full floating ends, narrow it to width and add Big Ford bearing ends(because they are so standard to brake kits), add Moser or Auburn Spool and Moser axles and Yukon gears. Gets done for about $1000. Cheapest I've been able to do my own 9" is about $1700 because of all the extra parts to make it strong enough. You are buying axles, spool, gears either way, but the Ford needs a brace, nod center, pinion support, 1350 yoke and that is the difference. A stock 9" is a pile of junk for performance use - cast center, small pinion support and bearings, cheap housing, small yoke - above 400hp it can become a problem.
Many times the 60 will also have good reusable 4.10 or 4.56 gears in them, and most have a 1350 yoke already, saving you more cash.. Weight difference is only about 20 lbs heavier than a braced nodular center Ford, you have to buy a more expensive aluminum center and pinion support to make a big difference. And the 60 is still stronger in the end.
About the only advantages to the 9" is the drop out center, for guys that travel to many tracks and need more than one gear set up, and weight if a lot of aluminum components are used.
Thats my point of view on it, may differ for others if you can't do your own housing narrowing work.