How big a torsion bar nick is ok?

72bluNblu said
I think you missed my point. It can’t be done.

Removing enough material to remove the stress risers from the damage will create a section of bar with a different diameter. With the way a torsion bar carries load that section will operate at a different torsional rate then the rest of the bar. It might last longer than running it as is, but eventually it will break in that spot. You’re just trading a stress riser fracture for a fatigue fracture in the section of bar with a narrowed diameter.

It can be done. All one has to do is remove material along a significant portion of the bar. Let's face it; even the hex ends are larger than the bar diameter (well, the new bars not so much), and they don't break at the ends because the radius is large enough.

As I said....IF you can guarantee those three things...otherwise, not worth it.