cliffyk

For whatever reason the inner race spun on the pinion shaft--with a tapered bearing the preload could have been too high and the bearing seized.

From what can be seen of the pinion itself, in the first photo, it does not appear to be damaged or even particularly run-in or worn--if the ring looks OK, and the price was right, I'd do as I said above and not be concerned.

I've repaired and installed shafts and bearings in industrial machinery, that carried much higher loads than a pinion on our cars, using those techniques. There's a company named Belzona which makes a complete series of products for dealing with scored and worn shafts, and bearing seats.

But as others have said, gears are cheap enough that if using those methods is of concern just buy a new set.


If it were a very expensive or irreplaceable part, or from a production machine that needed to be up and running ASAP--and very greatly worn/damaged--it could be flame sprayed and remachined.