Are rear spring plates / t-bar sockets hardened?
 

I'm preparing to have my spring plates and covers re-plated with cadmium, and my local plating shop said that anything over 34C on the Rockwell hardness scale should be pre and post baked to make sure they don't get brittle.

I'm pretty positive that the covers are just tin, and I'm guessing that the plate is just soft steel, so I'm not worried about those two parts.

What about the splined t-bar socket? Anybody know if that's hardened, and to what grade? I'm guessing that they're not hardened, but thought I would sanity check with the group before I drop off the parts.

Thanks!

dont know... but if you take a file to it (very lightly) and it doesnt even scratch it, its hard....any cutting with a good regular file and its just metal

Go ahead and have the plates and covers cad plated,you're not the first one and my guess is that they are just 4130 mild steel ...
If they were any stronger it would make them more brittle and prone to cracking.

As far as the torsion bars,they need to have a certain torsional rigidity and i would listen to your shop's advice.What they refer to is stress relief where you bring the metal to a certain temperature so the structure of the molecules does not get affected by the plating treatment !

Cheers !
Phil

I think they are talking about a post-plating bake to let the hydrogen diffuse and relieve stress.

I think the covers are steel, not tin.

The spring plates need to be somewhat hardened so that they do not plastically deformed as they flex through suspension motion, but not very hard so as to brittle fracture.