Axle flange size

[hossdoc]

In researching a new axle for my '71 Mustang I noticed that all the Ford 9" manufacturing companies make a big deal about "upgrading" to the large Ford (Torino style) axle flanges. If memory serves, years ago engine builders went to large crank bearings with the theory being that it distributed the load over a greater area reducing wear. They found that this logic is flawed; the larger the bearing diameter the greater the rotational velocity of any point along the bearing surface, thus actually increasing wear. I'm sure that there is a balance to be struck when chosing bearing size.

My question is whether or not there really is a significant advantage to the larger bearing size in a rearend?

My Mustang currently has an 8" rearend in it with small Ford axle flanges. I just rebuilt the rearend to put the car on the road. I will likely upgrade to a 9" down the road, however, I would like to upgrade to wilwood discs in the rear now. I don't want to spend money twice to get what I want, nor do I want shoot myself in the foot assuming that I want to end up with 500 hp under the hood. Thoughts???

[SDMAN]

The big (3.150" OD) wheel bearing is available in at least 8 different flanges (bolt patterns). Symmetrical, large GM, small GM, small Ford, Large Ford, Granada Ford, Mopar and 49-64 BOP come to mind.

The large OD wheel bearing, while being larger, more importantly, allows the use of a thicker axle where it passes thru the bearing. This is the biggest reason for stepping up to the big bearing.

The Torino style's flange/bolt pattern is the one that most aftermarket rear brake kits are patterned to fit (for the 9"). The other important dimension (for brake kits) is the axle standout. Currently, the most common number is 2.500".

[David Pozzi]

I'm moving this to the regular Suspension section.
It isn't an advanced suspension topic.
David