Rearend back brace question

[Salt Racer]

...Another reason for shallow backspacing is shorter axles...

Ummm yeah, that's what I really don't understand. I don't see the advantage of shorter axles.

It reduces rotating mass, maybe by a couple of pounds on gun-drilled axles. But mass is so damn close to the center of rotation, so effect is very small. And like I said, I really can't see much benefit of several-pounds less unsprung mass at drag strips.

And longer axles allow some more torsional deflection, which handles shock loading a little better. The only possible down side I can see is this additional torsional deflection delays power transmission to the ground, but it's probably by milli-seconds or something. Sidewalls wrinkle and delay it anyway...



Am I missing something? If not, I guess it's another one of "hot rodder" things that I don't understand. I suppose wheel manufacturers are as much to blame. It's along the line of them selling negative-offset wheels for using as front wheels (as well as rear wheels for IRS'd vehicles) w/o any sort of disclaimer or warning.