It seems what you are calling the 'cast iron thingy' is what's
collectively known as the brake cylinder. This would include
the bleed screw, internal piston and rubber sealing parts.
The housing is cast aluminum (at least mine are) and passes
through the hole in the brake backplate. You can buy rebuild
kits for the brake cyls, but a whole new cylinder assembly is
cheap compared to the hassle of trying to rebuild your old one.
> When I heat this sucker super hot will I have destroyed they part
> the hardware is stuck in?
The rubber parts are toast. Buy a new cylinder, you'll be glad
Bob Sykes - - - __,@_\____ email@example.com
'78 Spitfires - -- }-0-----0-` firstname.lastname@example.org
"Tyranny, like hell, is not easily conquered; yet we have this
consolation with us, that the harder the conflict, the more
glorious the Triumph. What we obtain too cheap, we esteem too
lightly: it is dearness only that gives every thing its value."