Packard Forum Index » V-8 (1955-56)

If you can take service bulletin 325 at face value, all the old retainers should have been removed from stock and only the hardened ones were available after that. If they pass the 'file test', they're hardened.

Modifying the characteristics of an alloy steel is not as easy as it may appear. You have to know the composition of the alloy. Each alloy has its own heat treating diagram. The annealing temperature, quench medium and tempering temperatures have different affects on the material properties. You can't simply heat an unknown alloy to a high temperature and then drop in water or oil, you then have to heat it again to a lower temperature to temper it to reduce the as-quenched hardness to improve or change the other material properties such as fatigue strength, hardness, microstructure, yield strength, etc.

As for brake drums, typical gray cast iron comes in at least 8-10 different alloys and the strength of the alloy is determined mostly by the chemical composition and microstructure. Besides, don't you want the gently-wearing characterists of brake shoes against the softer iron? I would think a hard-surfaced iron would give you squealing brakes. The newer brakes in modern cars are mostly disc brakes and the alloys used are different and matched to the brake pad compositions to give good stopping ability, wear and quietness.