Q: What does the pedal pivot tube do, and why would I need a new one?

The pivot tube is the shaft the brake (or clutch) pedal assembly rotates on inside the pedal support. Decades of use scores and wears this surface, which is what causes a loose, sloppy pedal even after the bushings are replaced.

Q: Should I replace the pivot tube if I'm installing a ball bearing pedal support kit?

Yes, if your original shaft is worn or scored. Running new ball bearings against an old, worn mild-steel shaft won't last - a soft, scored shaft makes a poor bearing race and will chew up the new bearings quickly. Pairing fresh bearings with a fresh pivot tube gives the smoothest, longest-lasting result.